BASICS OF MUSCULOSKELETAL ULTRASOUND. [2 ed.] 9783030739058, 3030739058

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James M. Daniels William W. Dexter Editors

Basics of Musculoskeletal Ultrasound Second Edition

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Basics of Musculoskeletal Ultrasound

James M. Daniels  •  William W. Dexter Editors

Basics of Musculoskeletal Ultrasound Second Edition

Editors James M. Daniels

William W. Dexter

Departments of Family and Community Medicine and Orthopedic Surgery Southern Illinois University School of Medicine

Sports Medicine and Family Medicine Maine Medical Center, Tufts University School of Medicine

Quincy, IL USA

Portland, ME USA

ISBN 978-3-030-73905-8    ISBN 978-3-030-73906-5 (eBook) https://doi.org/10.1007/978-3-030-73906-5 © Springer Nature Switzerland AG 2021 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Switzerland AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland

Preface

It’s hard to believe that it’s been almost a decade since the first edition of Basics of Musculoskeletal Ultrasound was published. Dex thought it was time for an update, and he was right! Point of Care Ultrasound (POCUS) has profoundly changed the way we diagnose and treat musculoskeletal conditions and sports-related injuries. This technology decreases the cost and the time needed to make a diagnosis while increasing our accuracy several fold. POCUS has brought “the joy of practicing medicine” back to both clinicians and patients through its inherent “therapeutic touch.” What is even more amazing is the impact it has made on how we train students, residents, and fellows. They no longer memorize two-dimensional anatomy. They experience three-dimensional physiology and pathology. This edition would not be possible without the hard work of the chapter authors (both new and old): Linda Savage, Tracy Marton, and Debbie Cramsey. This took a bit longer than expected as we hit a few bumps on our journey. While we were working on this project, both Dex’s mother and my mother passed. My mother was my first and greatest teacher. . . I am sure Dex feels the same way about his mother. This book is completed in their memory. They may be gone from us physically, but they will forever live in our hearts. Quincy, IL, USA

James M. Daniels

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Acknowledgments

Our thanks for image optimization, patience, and perseverance to Aimee Torraca Kohan, RDMS, RVT, CTT+, Application Specialist, Philips Healthcare. James M. Daniels Many thanks to my fellows, past and present, who give me direction and purpose and joy in what I do. I hope that this second edition will help bring this game-changing technology to a new group of clinicians. Aimee K – your help and patience with me as we re-illustrated this edition went above and beyond – thank you. And, as always, to my talented and patient wife, Cindy, for bearing with me through all the editing. And to our children, Ben, Sam, and Hannah, on whom I practiced my ultrasound skills and with whom I will now surely move on to the next adventure. William W. Dexter

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Contents

1 Introduction�����������������������������������������������������������������������������������������������������������������   1 James M. Daniels and William W. Dexter 2 Understanding Accreditation and Certification in Musculoskeletal Ultrasound ���������������������������������������������������������������������������������   3 Krystian Bigosinski 3 Choosing Ultrasound Equipment �����������������������������������������������������������������������������   7 Krystian Bigosinski 4 Knobology�������������������������������������������������������������������������������������������������������������������  11 Adriana Isacke 5 Tissue Scanning�����������������������������������������������������������������������������������������������������������  15 J. Herbert Stevenson 6 Hand and Fingers�������������������������������������������������������������������������������������������������������  27 Matthew C. Bayes 7 Wrist�����������������������������������������������������������������������������������������������������������������������������  51 Joseph J. Albano 8 Elbow���������������������������������������������������������������������������������������������������������������������������  75 Heather M. Gillespie and Pierre d’Hemecourt 9 Shoulder�����������������������������������������������������������������������������������������������������������������������  95 Mark E. Lavallee 10 Foot and Toes��������������������������������������������������������������������������������������������������������������� 117 Kate Quinn 11 The Ankle��������������������������������������������������������������������������������������������������������������������� 131 John Hatzenbuehler 12 Knee����������������������������������������������������������������������������������������������������������������������������� 147 Ashwin N. Babu and Eric T. Chen 13 Hip ������������������������������������������������������������������������������������������������������������������������������� 169 Lauren Elson, Raymond Chou, and David Robinson 14 Groin ��������������������������������������������������������������������������������������������������������������������������� 191 Christine Eng and Steven A. Makovitch 15 Ultrasound Guidance of Procedures������������������������������������������������������������������������� 213 Erik S. Adams

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16 Rheumatologic Findings��������������������������������������������������������������������������������������������� 237 Ralf G. Thiele, Sarah H. Chung, and Elizabeth T. Jernberg 17 Approach to Peripheral Nerves��������������������������������������������������������������������������������� 247 Adam J. Susmarski 18 POCUS in Sports Medicine��������������������������������������������������������������������������������������� 257 Dae Hyoun (David) Jeong and Erica Miller-Spears Index������������������������������������������������������������������������������������������������������������������������������������� 283

Contents

Contributors

Erik  S.  Adams, MD, PhD Montana State University, Department of Mechanical and Industrial Engineering; Bozeman Sports Medicine, Bozeman, MT, USA Joseph J. Albano, MD  Albano Clinic, University of Utah, Adjunct Instructor in Family & Preventive Medicine, University of Utah, Salt Lake City, UT, USA Ashwin N. Babu, MD  Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA, USA Matthew C. Bayes, MD  Founding Partner Bluetail Medical Group, Chesterfield, MO, USA Krystian  Bigosinski, MD  Maine Medical Partners Department of Orthopedics and Sports Medicine, Portland, ME, USA Primary Care Sports Medicine Fellowship Faculty, Maine Medical Center, Portland, ME, USA Eric T. Chen, MD  Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA, USA Raymond Chou, MD  Spaulding Rehabilitation Hospital, Physical Medicine & Rehabilitation, Charlestown, MA, USA Sarah  H.  Chung, MD  Division of Rheumatology, Department of Medicine, University of Washington Medical Center, Seattle, WA, USA Pierre  d’Hemecourt, MD Division of Sports Medicine, Primary Care Sports Medicine, Director of Sports Ultrasound Program, Boston Children’s Hospital, Boston, MA, USA James M. Daniels, MD, MPH, RMSK  Departments of Family and Community Medicine and Orthopedic Surgery, Southern Illinois University School of Medicine, Quincy, IL, USA William  W.  Dexter, MD, FACM Sports Medicine and Family Medicine, Maine Medical Center, Tufts University School of Medicine, Portland, ME, USA Lauren Elson, MD  Spaulding Rehabilitation, Charlestown, MA, USA Harvard Medical School, Somerville, MA, USA Christine Eng, MD  Harvard Medical School, Spaulding Rehabilitation Hospital, Department of Physical Medicine and Rehabilitation, Charlestown, MA, USA Heather M. Gillespie, MD, MPH  Maine Medical Partners Orthopedics and Sports Medicine, South Portland, ME, USA John Hatzenbuehler, MD  St. Luke’s Hospital, Department of Family and Sports Medicine, Hailey, ID, USA Adriana Isacke, DO  Family Medicine/Sports Medicine, Scarborough, ME, USA

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Dae  Hyoun  (David)  Jeong, MD, FAAFP, RMSK, RDMS Sports and Musculoskeletal Medicine at SIU-FCM, World Taekwondo Medical and Anti-Doping Committee, SIU-SOM Affiliated Hospital, Family and Community Medicine, Springfield, IL, USA Elizabeth T. Jernberg, MD  Division of Rheumatology, Department of Medicine, University of Washington Medical Center, Seattle, WA, USA Mark E. Lavallee, MD, CSCS, FACSM York Sports Medicine Fellowship Program, York, PA, USA Department of Family Medicine, Pennsylvania State University, School of Medicine, Hershey, PA, USA Department of Family, Drexel University, Philadelphia, PA, USA Gettysburg College, Gettysburg, PA, USA International Weightlifting Federation, Medical Committee, Budapest, HUN, Hungary USA Weightlifting, Sports Medicine Society, Colorado Springs, CO, USA Thomas Hart Family Practice Center, York, PA, USA Steven A. Makovitch, DO  Harvard Medical School, Spaulding Rehabilitation Hospital, VA Boston Healthcare System, Department of Physical Medicine and Rehabilitation, Charlestown, MA, USA Erica Miller-Spears, PA-C, ATC, RMSK  Department of Family and Community Medicine Quincy, Southern Illinois University School of Medicine, Springfield, IL, USA Kate  Quinn, DO Maine Medical Partners Orthopedics and Sports Medicine, Division of Sports Medicine, South Portland, ME, USA David Robinson, MD  Spaulding Rehabilitation Hospital, Department of Physical Medicine and Rehabilitation, Charlestown, MA, USA J. Herbert Stevenson, MD  Department of Family and Community Medicine, University of Massachusetts Medical Center, University of Massachusetts Medical School, Worcester, MA, USA Department of Orthopedics and Rehabilitation, University of Massachusetts Medical Center, University of Massachusetts Medical School, Worcester, MA, USA Adam J. Susmarski, DO, FAAPMR, CDR, MC, USN  Medical Corps, United Sates Navy, United States Naval Academy, Department Head Brigade Orthopedics and Sports Medicine, Annapolis, MD, USA Ralf  G.  Thiele, MD Division of Allergy/Immunology and Rheumatology, Department of Medicine, University of Rochester, Rochester, NY, USA

Contributors

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Introduction James M. Daniels and William W. Dexter

Clinical ultrasonography has been around for decades. In Europe, it also has been used for many years, but the way it is utilized differs from the system developed in North America. In Europe, ultrasound scanning is introduced to medical students very early in their training. These skills are then supplemented in postgraduate training. In the United States, clinical examination skills are taught to all students, but very few are exposed to clinical ultrasonography. Traditionally, a clinician examines the patient, and if it is determined that an ultrasound study is necessary, a comprehensive scan is performed by a highly trained technician, a sonographer. The images are then interpreted by a highly trained physician, a radiologist, who then generates a detailed report back to the clinician. This paradigm has shifted slightly over the years, with cardiologists and obstetricians using ultrasound as a bedside tool to practice medicine, but this training is limited in scope and is only taught in residency or fellowship. Recently, the United States has adopted a hybrid of these two systems, referred to as “point-of-care” ultrasonography. Students and practicing clinicians are now being trained to use bedside ultrasound as an important tool to diagnose and treat patients (i.e., starting central lines in the ICU, FAST scans in the emergency department, dynamic scanning of shoulder joint). More and more medical schools and residency programs are integrating POCUS into their physical examination and clinical reasoning curriculum. This model integrates the history and physical exam along with treatment decisions into one process by one clinician. It not only decreases the cost and time of the process, it allows the clinician to evaluate three-dimensional real-time anatomy J. M. Daniels (*) Departments of Family and Community Medicine and Orthopedic Surgery, Southern Illinois University School of Medicine, Quincy, IL, USA e-mail: [email protected] W. W. Dexter Sports Medicine and Family Medicine, Maine Medical Center, Tufts University School of Medicine, Portland, ME, USA e-mail: [email protected]

and physiology, which further adds to the accuracy of the diagnosis. These “point-of-care” musculoskeletal ultrasound exams (POC MSK/US) may not always include the “comprehensive” evaluation that traditional ultrasound examinations do. These scans are to supplement the clinical examination and should not be used as a stand-alone way to diagnose the patient’s condition. The use of the ultrasound machine can be compared to the use of a stethoscope in the clinical setting. The stethoscope, as we know it, was first used in France in the early 1800s by Dr. René Laennec, but it wasn’t widely used until the mid-1900s, when Rappaport and Sprague were able to massproduce a lightweight, relatively affordable model. Ultrasound technology is currently following this trend. We predict that POC US will be the stethoscope of the twenty-first century. In fact, the year 2013 was heralded as “The Year of Sonography” by a number of health-care organizations. The use of POCUS has vastly changed the way musculoskeletal medicine is now being practiced. Most textbooks on this subject are written by radiologists with years of experience in the traditional paradigm described above. This book is written by busy clinicians with decades of experience using clinical ultrasound and could be used as a stand-alone curriculum for POC MSK/US. This book is laid out in a way to become a bedside aid to assist in POC MSK/US scanning. Each chapter emphasizes one particular skill set. Introduction chapters demonstrate knobology, tissue scanning techniques, and the certification/ accreditation process for MSK/US.  Later chapters concentrate on particular regions of the body and explain detailed anatomy with “clinical scanning pearls.” This book was developed to be used at bedside, and the best advice we can give clinicians who want to incorporate these skills is to “PRACTICE! PRACTICE! PRACTICE!” If you wait until you have perfect recall of all the anatomy and flawless scanning technique to start doing POCUS examinations on patients, you will never be able to fully utilize this technology. These skills are integrative, not additive. In addition, POCUS allows us to touch our patients, which has been shown to increase both patient and provider satisfaction when it comes to providing health care.

© Springer Nature Switzerland AG 2021 J. M. Daniels, W. W. Dexter (eds.), Basics of Musculoskeletal Ultrasound, https://doi.org/10.1007/978-3-030-73906-5_1

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Understanding Accreditation and Certification in Musculoskeletal Ultrasound Krystian Bigosinski

 hat Is the Difference Between W Accreditation and Certification for Musculoskeletal Ultrasound? It is important to understand the essential differences between accreditation and certification.

Accreditation The term “accreditation” is typically used to refer to practices, not people. Therefore, a person or group of people can choose to have their practice “accredited” by a recognized accrediting body. The accrediting body awards practice accreditation to those practices that adhere to certain standards. The standards themselves may vary among different organizations but would generally include language concerning the qualifications of the people performing in that practice, the equipment used (type and maintenance), and the logistics of the practice (patient scheduling, documentation, use of protocols, emergency plans, etc.). Common examples would be fellowship accreditation by the American College of Graduate Medical Education (ACGME) or hospital accreditation by the Joint Commission on Accreditation of Healthcare Organizations (JCAHO).

Certification The term “certification” is typically used to refer to people/ individuals and not practices. Therefore, a person may become certified in a field or technique by demonstrating that he or she has met specific standards. For the most part, K. Bigosinski (*) Maine Medical Partners Department of Orthopedics and Sports Medicine, Portland, ME, USA Primary Care Sports Medicine Fellowship Faculty, Maine Medical Center, Portland, ME, USA e-mail: [email protected]

this includes documentation of prerequisites (e.g., continuing medical education [CME] and/or years of experience) and passing some type of test (written and/or practical). Individual certification may be used to document an individual’s competency in support of an application for practice accreditation, but practice accreditation will not typically suffice to obtain certification. The obvious example is that many, if not most, American Medical Society for Sports Medicine (AMSSM) members are “certified” in sports medicine once they meet the prerequisites (e.g., completion of fellowship) and pass the test that is managed by an outside institution (Board of Medical Examiners).

 hat Organizations Have Set Up a System W for Accreditation and Certification? Accreditation Practice accreditation for musculoskeletal ultrasound (MSK/ US) is currently available through the American Institute of Ultrasound in Medicine (AIUM). The AIUM is a nonprofit, multidisciplinary organization dedicated to advancing safe and effective use of ultrasound in medicine through professional and public education, research, development of guidelines, and practice accreditation. Although the AIUM promotes all subfields of ultrasound medicine, the organization has recently focused on the emerging field of MSK/US, supporting guideline development, education, advocacy, and, of course, practice accreditation. The AIUM has a long history of practice accreditation and is recognized as a legitimate accrediting organization by CMS and third-party payers. At this time, AIUM practice accreditation is the only available practice accreditation in MSK/US. You do not have to be a member of the AIUM to have the AIUM accredit your practice. We are currently not aware of any other organizations developing practice accreditation in MSK/US. If you are interested in learning more about the AIUM and practice accreditation, go to http://www.aium. org, the official web site of the AIUM.

© Springer Nature Switzerland AG 2021 J. M. Daniels, W. W. Dexter (eds.), Basics of Musculoskeletal Ultrasound, https://doi.org/10.1007/978-3-030-73906-5_2

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Certification Individual certification for MSK/US has been developed by the American Registry for Diagnostic Medical Sonography (ARDMS). The ARDMS is a nonprofit organization that promotes quality care and patient safety through the certification and continuing competency of ultrasound professionals. Similar to the AIUM, the ARDMS is a well-established organization recognized by CMS and third-party payers as a legitimate certifying/credentialing certification. In fact, most sonographers you know have received one or more credentials (or certificates) from the ARDMS—for example, Registered Diagnostic Medical Sonographer (RDMS) and Registered Vascular Technologist (RVT). The ARDMS has developed two comprehensive examinations, sonography principles and instrumentation and musculoskeletal sonographer, and these two examinations must be completed within 5 years, in addition to meeting examination requirements. The final prerequisites for the ARDMS test are extensive, are specific to level of education, and can be found here: https:// www.ardms.org/wp-­c ontent/uploads/pdf/ARDMS-­ General-­Prerequisites.pdf. In general, applicants must be able to document clinical experience with a minimum of 800 studies in the area for which they are applying. It should be noted that the AIUM and ARDMS are, in a sense, “sister” organizations that complement, not compete, with each other. This is similar to the ACGME and the Board of Medical Examiners. The American College of Rheumatology has also developed a certification process for rheumatologists who perform MSK/US, which can be found here: https://www.rheumatology.org/Learning-­Center/ RhMSUS-­Certification.

 hat Are the Standards and Guidelines W for the Accreditation of Ultrasound Practices? The AIUM web site has very detailed information on this process: https://www.aium.org/accreditation/accreditation. aspx. AIUM practice accreditation is based largely upon the published AIUM guidelines for Performance of the Musculoskeletal Examination and Qualifications for Performing the MSK/US Examination, both available for free at the AIUM web site. The accreditation application includes sections in which the practice documents compliance with these guidelines. In addition, practices are required to list the different locations in which scanning is performed, who performs the scanning, which US machines are used, what type of US machine maintenance schedule is in place, what scanning protocols are utilized, how patients are sched-

K. Bigosinski

uled, and how studies are documented in a timely manner. Practice guidelines for the performance of MSK/US as well as training guidelines are also included on this site for free.

 hat Are the AIUM Practice Guidelines W for the Performance of the Musculoskeletal Examination? These are available on the AIUM web site and are free. They can be viewed at this link: http://www.aium.org/resources/ guidelines/musculoskeletal.pdf.

 hat Are the Current AIUM Training Guidelines W for Physicians Who Evaluate and Interpret Musculoskeletal Ultrasound Exams? These are available on the AIUM web site and are free. They can be viewed at this direct link: https://aium.org/resources/ viewStatement.aspx?id=51. Key items that are pertinent are noted below. You should familiarize yourself with the full document on the web site. In summary, a number of pathways can be taken: 1. Completion of a residency and/or fellowship program that includes structured MSK ultrasound training and performance and/or interpretation and reporting of 150 diagnostic MSK ultrasound examinations, under the supervision of a physician qualified to perform MSK ultrasound examinations. If completion of residency and/or fellowship occurred more than 36 months ago: (a) The supervision and/or performance, interpretation, and reporting of at least 50 diagnostic MSK ultrasound examinations per year and 10  hours of AMA PRA Category 1 Credits™, American Osteopathic Association (AOA) Category 1-A Credits, or Council on Podiatric Medical Education (CPME)-approved credits specific to MSK ultrasound within the previous 36 months must be documented. (b) If the supervision and/or performance and interpretation of 50 diagnostic MSK ultrasound examinations per year cannot be documented, 30  hours of AMA PRA Category 1 Credits™, AOA Category 1-A Credits, or CPME-approved credits specific to MSK ultrasound must be completed, including at least 1 ultrasound course that provided hands-on training in MSK applications. 2. Completion of a residency and/or fellowship program in which the physician did not receive specific training in MSK ultrasound but can document subsequent involvement in the supervision and/or performance,

2  Understanding Accreditation and Certification in Musculoskeletal Ultrasound

interpretation, and reporting of 150 diagnostic MSK ultrasound examinations, plus 30  hours of AMA PRA Category 1 Credits™, AOA Category 1-A Credits, or CPME-approved credits specific to MSK ultrasound within the previous 36  months, including at least 1 ultrasound course that provided hands-on training in MSK applications. 3. Completion of the American College of Rheumatology Musculoskeletal Ultrasound Certification in Rheumatology program. If completion of certification occurred more than 36  months ago, 10  hours of AMA PRA Category 1 Credits™ or AOA Category 1-A Credits specific to MSK ultrasound must be documented.

Continuing Medical Education The physician should complete 10 h of AMA PRA Category 1 Credits specific to MSK/US every 3 years.

 hat Are the Case Study Submission W Requirements for AIUM Certification? Practices will need to submit five cases for review by experts identified by the AIUM staff. These five cases should be representative of your practice. If the practice is a solo practice, then all cases can come from one clinician. However, if more than one person is scanning in the practice, then cases should come from multiple individuals, and you cannot submit two cases from a single physician/clinical provider unless all providers have been represented at least once. Similarly, if the practice evaluates all body regions, then the practice should not submit five shoulder examinations. For each case, the practice will submit all the US pictures and the report. The submitted pictures should comply with AIUM scanning protocols (i.e., Guidelines for Performance of the MSK/US Examination) and be labeled appropriately. The reports should justify the indication for the examination, and the stated results should accurately reflect the submitted US pictures. The AIUM has a well-established protocol for managing the process within HIPAA guidelines. Additional detailed information can be found at https://www.aium.org/accreditation/caseStudyRequirements/mskDiagnostic.pdf.

 ow Much Will Accreditation H and Certification Approximately Cost? AIUM practice accreditation is based on the number of ultrasound machines and specialties represented and starts at $1250. The fee schedule can be found here:

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https://www.aium.org/accreditation/fees.pdf. ARDMS MSK examination cost is $250, and further information can be found here: https://www.ardms.org/get-­c ertified/ rmsks/.

 o I Need to Get Certified for Payment D from Insurance Companies? Neither practice accreditation nor personal certifications are necessarily tied to reimbursement. As outlined in their mission statements, the primary goals of the ARDMS and AIUM are to ensure best practices and patient safety. An analogy would be board certification in sports medicine. You certainly don’t need to be certified in sports medicine to get reimbursed. The primary purpose of the sports medicine board is to ensure best practices in sports medicine; the board was not developed to ensure reimbursement. There is some precedent for CMS and third-party payers to utilize certification and practice accreditation to control patient access and reimbursement. For example, some insurance companies will not pay for imaging done at nonaccredited imaging centers, whereas others may only reimburse interventional spinal procedures performed by specialist’s board certified in pain medicine. The reality is that practice accreditation and certification do set a minimum standard that third-party payers may utilize to ensure a minimum standard of care for their patients. Above and beyond the issue of reimbursement, there may be implications for marketing. Practices have certainly utilized specialty certifications and practice accreditations to distinguish themselves from competitors as part of a marketing strategy. Only time will tell how accreditation and certification will impact patient access and reimbursement.

 o Accreditation and Certification Bodies D Handle Diagnostic Ultrasound and Ultrasound for Needle Guidance Procedures Differently? At this current time, the practice accreditation process pertains to diagnostic ultrasound. This means that practices should submit diagnostic ultrasound cases for review as part of their accreditation application. Although not specifically stated, it may be assumed that a practice accredited in MSK/US is accredited for diagnostic and interventional aspects. The AIUM has plans to develop practice guidelines for US-guided interventional procedures. How this will impact the MSK/US accreditation process remains to be determined. Based on our current understanding, the ARDMS certification test is primarily, if not entirely, diagnostic. The emphasis on diagnostic

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ultrasound for practice accreditation and certification is in line with the general understanding that individuals using US for US-guided procedures should have a basic understanding of diagnostic US.  This reflects the European experience in which many clinicians are not taught US-guided procedures until they have met minimum requirements for diagnostic US.

K. Bigosinski

Suggested Reading American Institute of Ultrasound in Medicine at their website: http:// www.aium.org American Registry for Diagnostic Medical Sonography at their web site: http://ardms.org/ Bianchi S, Martinoli C.  Ultrasound of the musculoskeletal system. New York, NY: Springer; 2007. European Society of Musculoskeletal Radiology at their web site: http://www.essr.org/

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Choosing Ultrasound Equipment Krystian Bigosinski

Introduction Choosing an ultrasound system for musculoskeletal work can be a daunting task. With an increasing number of ultrasound vendors, each potentially offering a wide array of models with varying features, making a choice can be a challenge. A frequently asked question by those new to musculoskeletal ultrasound is “What system should I buy?” That’s akin to someone asking “What car should I buy?” The simple answer is “It depends.”

Console vs. Portable vs. Tablet/Smartphone The first choice is whether to purchase a cart-based console system or a portable system. Console systems are generally large-format cart units. Their main advantage lies in their processing power. The bigger platform allows for more powerful processors and cooling fans. This translates into potentially better images and the ability to drive a wider array of transducers. Most also have the capacity to keep multiple transducers plugged in simultaneously, simplifying the process of switching between them. While mobile (the carts all have casters), the size of console systems limits the ability to move them easily from room to room. Some have limited battery backup, which means that the unit must be fully powered down, unplugged, moved to the new location, and then plugged back in and rebooted. Most offices utilizing console systems, therefore, will dedicate a room to ultrasound, where the system takes up more or less permanent residence. For those new to musculoskeletal ultrasound, console systems have one major drawback. They cannot be taken home K. Bigosinski (*) Maine Medical Partners Department of Orthopedics and Sports Medicine, Portland, ME, USA Primary Care Sports Medicine Fellowship Faculty, Maine Medical Center, Portland, ME, USA e-mail: [email protected]

easily, which means that the user is limited to using the machine only while in the office. This may hamper learning for the ambitious student of ultrasonography. On the other hand, portable machines offer flexibility. The majority have battery backup built in, allowing the unit to be moved freely among exam rooms without having to power down each time. The portability also means the physician can take the unit home to practice, thereby significantly improving one’s skills much more quickly. Portable machines lack the processing power of the console systems, but for all but the most demanding applications, this is not a serious drawback. Portable units can easily handle the vast majority of musculoskeletal work. Most portable systems lack the ability to plug in multiple transducers simultaneously. To change transducers, the operator must unplug one transducer and plug in another. On those systems in which the transducer plugs into the bottom of the machine, changing transducers can be more cumbersome or difficult. If a portable machine is purchased, serious consideration should be given also to purchasing a mobile stand or a docking cart. A mobile stand holds the machine securely during use. Most also have various shelves for peripherals such as thermal image printers, CD burners, and holders for transducers. A docking cart, on the other hand, is a powered mobile stand into which the machine slides or docks, similar to a laptop docking station. It allows peripherals and several transducers to remain plugged into the cart; all you do is snap in/out the ultrasound machine. Stands and carts make it easier to move the machine around the office but also make it much less likely that the machine will fall off an exam table or counter. The cost of a stand is a small insurance premium. In addition, some stands, and most docking carts, have the ability to keep more than one transducer plugged in at the same time, and the choice of which transducer is active is made via the keyboard. (Keep in mind, however, that depending on the system you choose, not all attached transducers may be accessible while the system is operating in battery mode.)

© Springer Nature Switzerland AG 2021 J. M. Daniels, W. W. Dexter (eds.), Basics of Musculoskeletal Ultrasound, https://doi.org/10.1007/978-3-030-73906-5_3

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Finally, there is a new generation of handheld machines that use a platform such as a tablet or smartphone, combined with a probe and software. Some of these systems can be leased and provide an affordable point of entry for those new to ultrasonography. The systems are also the most mobile of all the choices. However, they are limited both by the processors on the device being used and by the technology of the probes, all of which result in decreased image quality overall. For all system types, also consider how you plan to store images. For example, if you work for a larger medical center that will allow you to use their radiology image servers, being able to upload images from the ultrasound machine directly onto a server and electronic medical record is desirable. Make sure you purchase any software and hardware upgrades needed for this at the time you purchase your machine, as adding them on later can incur unnecessary cost. Otherwise, storing them securely on an encrypted external hard drive may also be an option, and in that case, be sure to contact your information technology or medical informatics department to discuss how to do this securely to protect sensitive patient information. In either case, all machines have finite memory to store images and video, and in a busy ultrasound practice, storage will fill up quickly if data is not regularly uploaded. And regarding the handheld/tablet-based devices, there may be limitations regarding private patient information regarding these devices, so their role in a busy clinical setting may be limited as institutions may not want PPI being stored on tablets or smartphones. Before committing to one of these devices, it is best to think about how it will be used, and discussing how patient data will be stored with your medical informatics department may inform your decision.

Transducer Choices For musculoskeletal work, the workhorse transducer is the linear probe. The ideal multipurpose transducer should have a frequency range of roughly 8–12 MHz. The vast majority of musculoskeletal ultrasound work is done at 10 MHz, with a smattering at 12  MHz for the more superficial structures (within 2-cm depth) and some at 8 MHz for slightly deeper structures (4–5-cm depth). Some newer systems offer linear transducers that will scan at frequencies from 8 MHz to as high as 15–18 MHz. However, note that, depending on the particular system, you may not be able to choose the specific scanning frequency. Also, keep in mind that while a higher-frequency transducer may generate a higher-resolution image, it does so at the potentially heavy cost of severely limiting penetration or scanning depth, often to no more than 2 cm. (Remember that frequency and penetration are inversely related.)

K. Bigosinski

Although the majority of work done in musculoskeletal ultrasound is handled by the linear transducer, strong consideration should be given also to purchasing a curved transducer with a frequency range of roughly 3–5  MHz. The curved arrays are essential for work around the hip and buttocks (e.g., hip intra-articular injections) and spine work. However, curved probes can also be extremely helpful in other areas, such as the glenohumeral joint (which is relatively deep and not well visualized by some linear arrays), or in cases of large or obese patients, where the linear transducer lacks penetration. Finally, curved transducers can be helpful to start out getting a wider field of view of an area, for example, to help localize a tear in a muscle belly, and then the linear probe can be used to “zoom in” on the affected area. A wide assortment of specialized probes is also available, such as small-footprint “hockey stick” probes, small low-­ frequency curved arrays, and dedicated high-frequency probes. These specialized probes may be useful in practices or specialties that tend to do highly specialized ultrasound. For example, for rheumatologists who use ultrasound extensively to examine and inject the small joints of the hands and feet, a small-footprint high-frequency probe might be well worth the investment. New technology has recently produced probes that can be used for multiple purposes. This allows the clinician to use just one probe to scan virtually all parts of the body.

System Features: “Bells and Whistles” Features to look for when purchasing a system will largely be dictated by how one intends to use the system and to what extent one desires to develop expertise in musculoskeletal ultrasound. Some systems are engineered to be more or less “plug and play.” These machines have very limited ability to fine-tune images and settings. They are designed for those practitioners who simply want to turn on their machine and go to work. For example, there are systems available that lack the ability to adjust scanning frequency independently of scanning depth. The software “assumes” that when the depth is increased, the frequency must be correspondingly decreased to image deeper structures. While this is generally the case, there are times when one may want to decrease the frequency but not the depth. For example, sometimes it is easier to see a needle when performing a guided injection by using a lower frequency, but increasing the depth would compromise the quality of the image. Conversely, it may occasionally be desirable to increase the depth without changing the frequency, such as when scanning the posterior glenohumeral joint. The ability to adjust scanning depth varies by systems. Some machines “toggle” from one depth to the next, and you cannot go backward; you must continue to toggle forward

3  Choosing Ultrasound Equipment

and back around to the beginning. Likewise, some systems have limited—or no—ability to set and adjust focal points or zones. This is done automatically and determined by built-in software algorithms. Some systems are touch screen only; they lack a true keyboard. Similar to a tablet, they use a virtual keyboard that appears on the screen. While some units have separate time-gain compensator sliders (TGCs), others lack this feature or else have it built in to the software settings. TGCs are analogous to a graphic equalizer in a stereo system. They allow the user to adjust a particular band or portion of the image to compensate for variations in tissue density and attenuation. There are other helpful features to consider. The ability to do side-by-side on-screen comparisons, comparing the pathological side to the “normal” side, can be useful. Beam steer technology, the ability to angle the sound beam to make it more perpendicular to the needle to help in visualization, for example, can be quite useful when performing guided injections. Panoramic view can be helpful when trying to image a structure that extends beyond the visible area of the screen, such as when trying to capture an image of the entire length of the rectus femoris muscle. Annotation features are an important area to evaluate. How easy is it to label your images on-screen or to change the labels? Does the system offer the ability to create a custom “library” of commonly used terms? Some systems will use different libraries based on the particular scanning settings used, such as one library of annotation labels when scanning the foot and another library when scanning the shoulder. Post-image processing ability is yet another feature to consider. The ability to label, to relabel, or even to change the appearance of an image or to take a measurement after the image has been taken and saved can be important. Sometimes it can be more efficient to go back and label or fine-tune your images after the visit instead of slowing down while performing the actual exam to change labels. Some systems do not allow any post-image processing at all; once the image is saved, it cannot be labeled or altered. Finally, the ability to adjust the various parameters of power Doppler, such as pulse repetition frequency (PRF), wall filter, flash suppression, and gain, varies widely from one system to another. For those practitioners who utilize power Doppler to assess for neovascularity or synovitis or who find Doppler helpful to locate nerves via their attendant vascular structures, the ability to fine-tune Doppler settings can be an important consideration. Oftentimes ultrasound novices are intimidated by systems that have a high degree of adjustability. For many, a less complicated “set it and forget it” system will meet their needs perfectly. As one becomes more skilled in ultrasound, however, the desire to move beyond the basics can be hampered by the limitations of certain systems. In those cases,

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the choice becomes one of buying a more robust system from the outset and “growing into it” or choosing a system that is more user-friendly to start and then upgrading over time.

Warranties and Extended Service Contracts Ultrasound systems and probes are all expensive items. True to the saying, if something can break or go wrong, it will—at least, eventually. Most new systems come with a 1-year factory warranty. Beyond that, purchasing an extended warranty is worth considering. Transducers alone can cost up to $5000–10,000 to replace. In addition, most extended service contracts guarantee service within a specified period of time, often in 1–2 days. This minimizes system downtime and revenue loss. Without a service contract, you are often placed in a queue to wait for service, and repairs can be expensive. Not all extended service contracts need to be purchased from the manufacturer, nor do they need to be purchased with a new system. There are companies that specialize in selling used and demo ultrasound equipment, and many offer extended service contracts; in some cases, they offer better pricing and service than the manufacturer. By far the most important factor when choosing a system is to pick one that will meet anticipated needs while also fitting within any budget constraints. You should demo each system you are considering by having the company sales representative bring a machine to your office for a day or 2 to try on a variety of patients and scanning conditions. Most companies will gladly oblige such requests. Finally, there are many financing options for ultrasound machines, including outright purchase with or without a payment program, or leasing. Again, your individual practice budgetary resources or the approach of your purchasing and financial departments, if you are at a larger medical center, will inform these decisions. See Table 3.1 for a comparison of ultrasound machines.

Transducer Care and Cleaning Proper care and cleaning of ultrasound transducers is important, not only to maintain proper probe functioning but also to prevent infections and transmission of communicable diseases. The official position statement of the American Institute of Ultrasound in Medicine states, “Practices must meet or exceed the quality assurance guidelines specified in Routine Quality Assurance for Diagnostic Ultrasound Equipment” [1]: • Instrumentation used for diagnostic testing must be maintained in good operating condition and undergo routine calibration at least once a year.

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K. Bigosinski

Table 3.1  Ultrasound machine comparison Machine type Tablet/ handheld based

Cost Lowest

Cart based Typically in the middle Console based

Highest

Image quality Typically limited in depth, frequency, and optimization options compared to others Typically good ability to optimize images for most MSK applications

Image storage Limited; privacy may be a concern; not always DICOM compatible Some, usually DICOM compatible

Typically best image quality with the most imaging options, so of which may not be used in MSK scanning

Usually greater than cart, often DICOM compatible

• All ultrasound equipment must be serviced at least annually, according to the manufacturers’ specifications or more frequently if problems arise. • There must be routine inspection and testing for electrical safety of all existing equipment. Most ultrasound manufacturers offer guidelines for cleaning and maintaining the transducer. Practitioners are advised to follow the specific manufacturer’s guidelines to prevent voiding any warranties. However, many guidelines are more general. A generic cleaning protocol may include these points: • Clean the transducer after each use (follow the manufacturer’s guidelines). • For the most part, the transducer is going to be used on the skin and is not going to be exposed to blood or any other bodily fluids. Wiping the transducer off with a soft cloth using a mild soap and water is acceptable after each use. • An alternative to this is to clean the transducer with antimicrobial/germicidal wipes, with low alcohol content, a soft disposable cloth dampened with a bactericidal agent, or something similar. • Before proceeding with any sterile procedure (injection or placing transducer near an open wound or lesion on the dermis), the transducer should be cleaned using an antimicrobial wipe. Many practitioners use sterile sheaths, so the transducer is never directly exposed to bodily fluids. If this is not the case, care should be taken to not expose the transducer directly to bodily fluids. If this happens, follow manufacturer’s guidelines to properly sanitize the transducer. The following should also be considered to properly maintain the transducer:

Portability Highly portable

Probes Usually limited range of probes

Can be moved easily Broad range of probes, sometimes in cart or taken out need to unplug/plug of clinic in to change probes Broad range, often Usually designated push-button probe to a room, not easy changes to take to another clinic or training room

Screen size Small, tablet- or smartphone-sized screen Laptop-sized screen, usually clamshell with limited mobility Sometimes large, cinematic-sized screen on swing-arm for positioning

• Avoid direct contact of the transducer head and cable with sharp objects, such as needles or scalpels. • Do not clean the transducer with a brush or sponge without consulting the manufacturer, because these objects may damage the transducer head. • When cleaning or disinfecting the transducer cable, always elevate the head above the cable. This ensures that the liquid on the cable does not drip onto the transducer head. • Train all office staff with a written protocol/checklist for cleaning and maintenance of the ultrasound equipment.

Summary Choosing an ultrasound system involves consideration of a number of important variables, only one of which should be price. Intended use, the degree of desire of the provider to master ultrasound, and physical space limitations are also important factors. Almost all of the current ultrasound systems marketed toward the musculoskeletal market will do an adequate job for the majority of musculoskeletal work. However, it behooves the purchaser to at least consider some of those details outlined in this chapter. Price should actually be among the least of the factors considered. In the vast majority of cases, over time, your ultrasound system will more than pay for itself. And over the course of 3–5 years (the length of time most practices keep a system before upgrading), a few thousand dollars become much less ­significant than the benefits of having not only a system that meets your needs but also one that is a joy to use.

• It is always a good idea to reference the owner’s manual Reference or directly contact the company before using any non-­ 1. https://www.aium.org/accreditation/qualityAssurance.pdf referenced cleaner or sterilization techniques, so the transducer is not damaged.

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Knobology Adriana Isacke

The Machine The principles of image capturing and quality improvement of images should be similar regardless of the brand of machine being used, though the specific terms for such functions may be different. Refer to the machine’s user manual for the specifications.

Mode There are various types (modes) of ultrasound images that are commonly obtained. In B-mode (brightness mode) ultrasound, a linear array of transducers about the width of a credit card simultaneously scan a plane through the body that can be viewed as a two-­ dimensional image on screen. This is sometimes described as 2D mode, and it provides the single still images that are frequently used for documentation purposes to define structures. M-Mode (motion mode) is used to capture multiple images in sequence. In simple terms, it collects a video of a particular scan.

Doppler Mode The Doppler effect, where the sound frequency of an object changes as the object travels toward or away from the transducer, is used to help define the presence, direction, and velocity of blood flow on ultrasound. It is useful to help provide adequate information about the blood flow around a particular anatomical area. There are several different types of Doppler modes that can be used with most ultrasound machines. They are discussed below.

A. Isacke (*) Family Medicine/Sports Medicine, Scarborough, ME, USA e-mail: [email protected]

Color Doppler This mode is used to define blood flow by superimposing color on a gray-scale ultrasound image. The use of color Doppler helps determine whether blood flow exists (i.e., identifies location of blood vessels) and is conventionally set up to show blue color when the blood flows away from the transducer and red color when it flows toward it. Flow velocity cannot be measured within this feature. Clinical Application  When performing a joint injection – of the hip joint, for example  – the use of color Doppler can identify the location of blood vessels so the angle of approach can be set to avoid the path of the vessel.

 ulsed Wave or Duplex Doppler P This provides an image of a moving object along with its waveform. It shows both the presence of flow and defines the velocity of blood flow within a vessel. Clinical Application  During echocardiograms, this setting can define the presence and velocity of flow across a valve.

Power Doppler This is color Doppler mode with a high sensitivity to blood flow to help visualize small vessels or vessels with slow flow. This mode assigns color regardless of the direction in which the blood flow is traveling. Color will appear when there is increased perfusion of an area secondary to inflammation or neovascularization. The weakness in using this technique is that its high sensitivity can create artifact in certain situations, such as transducer motion, thus making it seem as though vessels are present when they are not. This typically appears as a dense area of “color” on the screen. Additionally, it does not tell directionality or velocity of the flow seen.

© Springer Nature Switzerland AG 2021 J. M. Daniels, W. W. Dexter (eds.), Basics of Musculoskeletal Ultrasound, https://doi.org/10.1007/978-3-030-73906-5_4

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Clinical Application  Power Doppler can be used to evaluate neovascularization of the patellar tendon in the setting of chronic tendinosis.

Frequency A transducer has an inherent ability to send a range of sound wave frequencies toward tissue, which are described by the unit’s megahertz (MHz). The higher the frequency of waves being sent, the higher the resolution of the image. However, higher frequency waves are unable to penetrate deeply in tissue and will be unable to clearly visualize deep structures. Low-frequency probes are able to penetrate tissue to find deeper structures and will provide a lower-resolution image.

Image Balance Gain Changing the gain is analogous to amplifying or suppressing the volume of signal in an image. By adjusting the gain up or down, visualization of certain structures becomes easier. Each ultrasound machine is equipped with an autogain feature, which is the machine’s interpretation of the optimal level of gain for the body part or structure being scanned. When first starting out with scanning, autogain is likely going to be a useful tool. We recommend adjusting the gain manually to affect the image quality, then comparing it to autogain for image improvement.

Time Gain Compensation The sound waves emitted by your transducer at the surface of the skin will attenuate as they travel through tissue on their way to the target. The time gain compensation (TGC) set of controls helps to fine-tune the gain in the areas of interest on the screen for improved visualization of the structures.

Depth The depth to which a sound wave can penetrate tissue is linked to the frequency capability within your transducer. As noted previously, a high-frequency probe will provide high-­quality images at a low depth, whereas a low-frequency probe will excel at visualizing deeper structure, though there may be a compromise in image clarity. When first starting an ultrasound examination, adjusting the depth of the picture is key to ensure that the structures of interest can be seen within the field of view. Each machine will have

A. Isacke

units of measure on the screen delineating (often in centimeters) the depth of the structure. Clinical Application  Depth can be helpful during an ultrasound-­guided injection. The depth will assist in determining the proper position and length of the needle needed to reach a particular structure.

Focal Zones Focal zones are used to visualize fine anatomy (i.e., follow a nerve course) or to focus the ultrasound beam on a particularly narrow anatomical region. Placing the object of interest into a focal zone ensures a higher-quality image of that object. It is best to minimize the number of focal zones used at a time, as the higher the number of focal zones, the image improvement will not be as robust. Clinical Application  When injecting a calcific tendinopathy, it may be wise to place the focal zone at the depth of the calcific density to optimize the image.

Documenting the Examination During scanning or while performing a procedure, it is best practice to systematically save pictures or videos that best represent the structures of interest.

Text Labeling an ultrasound image with text is an important step in documenting the examination for the medical record. The particular buttons that need to be used to label an image are specific to each machine. You can often initiate the text function while scanning if desired (i.e., placing “Right AC joint” on the screen to label multiple images of the same structure and allow for scanning of the structure to continue). You can also freeze the frame first and then add text. Several components should be included in your labeling – laterality, joint, structures of interest, whether the image was taken in short or long axis, and distal and proximal poles of the image. If the image is of an injection, it is important to delineate the needle position, gauge, and medication used.

Measurements There will be many times when a measurement of a particular object seen on a screen is important. It is important to first

4 Knobology

freeze the frame of the picture of the object you are trying to measure. Again, the specific keystrokes needed to measure an object are unique to each ultrasound machine.

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Clinical Exercise

1. Become familiar with the controls on the machine by doing the following: Clinical Application  Measurements of the median nerve in (a) Demonstrate that you can easily change the the carpal tunnel distally and at the level of the pronator mustransducers. cle can help in diagnosing carpal tunnel syndrome. (b) Label the scan with the patient’s name, date of birth, Measurements of cystic structures before drainage and after date of scan, and body part. drainage are important documentation to demonstrate suc (c) Adjust the depth of the field so the image takes up the cess in the intended purpose (in this case, draining a cyst) of whole screen. the ultrasound exam. (d) If your machine has presets for different tissues or body parts, select the appropriate one. (e) If your machine has focal zones, adjust those to the area that you want to scan (optional). Initial Steps (f) Adjust the gain on the machine in two extremes – one bright and one dark. Setting up your machine prior to scanning to get the highest-­ 2. Record a scanned image – one bright and one dark – with quality pictures possible is important. This includes choosing the above settings and patient identification. Practice to any presets that may be available on your machine (i.e., choose the point that this is “second nature” by holding the probe the body part you are intending to view; ensure you are in in one hand and adjusting the settings in the other. Save musculoskeletal imaging preset). Adding the patient’s name the two images for documentation/homework. and identifying information (i.e., date of birth) is important 3. Repeat the above process, but this time, record an image step for documenting the examination. Ensure the transducer with: you wish to use is connected to the machine. You can predict (a) Caliper measurements of a structure on the scan. somewhat which transducer you will need by considering the Measure length, width, and circumference of the depth of the object you are intending to study (i.e., the carpal structure. tunnel is very shallow; the hip joint is very deep) and the size (b) Perform a dynamic scan, such as the impingement of the object you wish to study (i.e., it will be easier to use a exam of the shoulder or valgus stressing of the ulnar small probe for fingers, larger probe for the shoulder). collateral ligament of the thumb or elbow. As you begin your scanning of a particular body part, you (c) Turn on the color Doppler and identify an artery and will first adjust the depth until the image can be seen in the vein. field of view. It is important to start with the depth set at (d) If your machine has the capability, perform a panmaximum so structures are not missed. The depth can then oramic exam of the structure such as the Achilles or be adjusted to provide the best screen image. patellar tendon. Next, adjust your focal zone. On some ultrasound machines, the focal zone can be adjusted to a specific location within the field. On other machines, you will adjust either the superficial or deeper zone depending on where the Suggested Reading object you are visualizing lies. When first using this machine, Bianchi S, Martinoli C.  Ultrasound of the musculoskeletal system. you may omit this step. New York City, NY: Springer; 2007. Next, adjust the gain on the screen as needed. By adjust- European Society of Musculoskeletal Radiology. https://www.essr.org/. ing the gain, you will see that certain structures come into Jacobson JA.  Fundamentals of musculoskeletal ultrasound. 3rd ed. Philadelphia, PA: Elsevier; 2017. better view. Remember that you may need to readjust the settings on the Stoller DW.  Stoller’s atlas of orthopedics and sports medicine. MDL Lippincott Williams & Wilkins: Baltimore; 2008. screen as you scan for different views of anatomical structures.

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Tissue Scanning J. Herbert Stevenson

Ultrasound Equipment Ultrasound equipment at its most basic level includes a transducer (probe) connected to an ultrasound computer that includes a CPU, monitor, keyboard, transducer controls, hard drive, and sometimes a printer (Fig. 5.1). The transducer contains quartz crystals that utilize the piezoelectric electric effect, which transforms electrical current into sound waves and vice versa. The piezoelectric effect allows the probe to generate sound waves that propagate through soft tissue. Probes come in different shapes and sizes (Fig. 5.2); their use depends upon the clinical indication. A linear probe is most often utilized in musculoskeletal medicine as it allows for more accurate evaluation of structures close to the skin surface. A curvilinear probe by comparison allows great resolution of deeper structures. Linear probes transmit at a higher frequency, generally in the range of 8–18 MHz. The higher frequency allows them to obtain greater resolution of near-field structures at the sacrifice of depth and penetration. When greater depth of visualization is required, a curvilinear probe is preferred. Common clinical indications in musculoskeletal ultrasound for utilization of a curvilinear probe include ultrasound of the hip, spine, and glenohumeral joint. Ultrasound of small structures, including the hands and feet, may be best visualized with a small-footprint probe such a “hockey stick” probe. The sound waves are able to be reflected back or echo at varying rates depending upon the type of tissue they encounter. The probe is then able to receive the mechanical sound waves and transform them into an electric current that can be analyzed by the CPU.  The data are subsequently displayed as two-dimen-

sional real-time images on the screen. There is now new technology available to perform this task using a computer chip. This innovation allows the use of just one probe to do all tissue scanning.

Anatomic Terminology A thorough understanding of body sections and anatomical planes is required in order to properly perform and interpret musculoskeletal ultrasound images. Body sections can be

J. H. Stevenson (*) Department of Family and Community Medicine, University of Massachusetts Medical Center, University of Massachusetts Medical School, Worcester, MA, USA Department of Orthopedics and Rehabilitation, University of Massachusetts Medical Center, University of Massachusetts Medical School, Worcester, MA, USA e-mail: [email protected]

Fig. 5.1  Image of ultrasound equipment

© Springer Nature Switzerland AG 2021 J. M. Daniels, W. W. Dexter (eds.), Basics of Musculoskeletal Ultrasound, https://doi.org/10.1007/978-3-030-73906-5_5

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16 Fig. 5.2 (a, b, c) Linear, curvilinear, and “hockey stick” probe

J. H. Stevenson

a

b

c

Lateral

divided into sagittal, transverse, and coronal planes (Fig. 5.3). A sagittal plane is a vertical plane passing from front to back through the body separating it into a left and right partition. A transverse plane is one that passes along a horizontal plane dividing the body into an upper and lower partition. A coronal plane is a vertical plane passing from side to side that divides the body into ventral and dorsal partitions. Anatomic definitions illustrated in Fig. 5.3 include anterior, posterior, proximal, distal, lateral, medial, cranial, and caudal.

Medial

Lateral Posterior

Proximal

Cranial

Anterior

Ultrasound Terminology Ultrasound terminology differs from descriptive terminology utilized in other modalities such as MRI because it describes the echogenicity of the structures being imaged. Echogenicity refers to the extent to which different substances and structures within the body reflect sound waves. The greater the percentage of sound waves that are reflected from a particular structure, the higher the echogenicity of the structure detected by the probe. Different tissue types will produce unique echogenic images that tend to be consistent across tissue types (i.e., muscle, tendon, bone). The higher a structure’s echogenicity, the brighter it will be displayed on the monitor. Conversely, the lower a structure’s echogenicity, the darker it will appear (Fig. 5.4a, b). The following is a list of descriptive ultrasound terminology: • Hyperechoic (HYPER): high reflectivity displayed as a bright or light signal. Bone (radial head (RH)) and tendon are examples of hyperechoic objects.

Tra ve nspla rse ne

Distal

al gitt Sa ne Pla

Cor o Pla nal ne

Caudal

Fig. 5.3  Sagittal, transverse, and coronal planes. Anterior, posterior, proximal, distal, lateral, medial, cranial, and caudal. (Adapted from http://msis.jsc.nasa.gov/images/Section03/Image64.gif)

5  Tissue Scanning

a

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b

Fig. 5.4 (a) Lateral elbow: examples of hyperechoic (HYPER), isoechoic (ISO), hypoechoic (HYPO), anechoic (AN). (b) Short-axis view of hyperechoic median nerve (MN) and anechoic ulnar artery (UA)

a

b

Fig. 5.5 (a, b) Proper handling of an ultrasound probe

• Isoechoic (ISO): when two adjacent objects are of equal echogenicity (common extensor tendon (CET) and fascia). • Hypoechoic (HYPO): low reflectivity displayed as a darker area. Muscle fiber bundles are an example of hypoechoic structures (muscle fibers). • Anechoic (AN): absence of ultrasound reflectivity/signal displayed as a black area. Fluid and articular cartilage are commonly displayed as anechoic.

 echnical Aspects of Ultrasound Image T Acquisition The ability to acquire a clear and accurate image with musculoskeletal ultrasound requires a systematic approach along with a sound understanding of three-dimensional anatomy. Additionally, the ability to manipulate the probe in its three

planes of movement is crucial, as even slight alterations in probe position will significantly affect the quality of the image. Ultrasound competency requires routine practice and repetition to become proficient in its use.

Probe Handling Probe handling is essential to the proper performance of an accurate and repeatable ultrasound exam. A steady and secure handling of the probe will facilitate a clear image with minimal artifact. The probe should be held in a steady but not rigid grip between the thumb on one side of the probe and the second and third fingers on the other side. The fourth and fifth fingers, along with ulnar/hypothenar aspect of the palm, should rest on the skin of the patient examined. This connection to the patient at all times will facilitate a secure platform from which to manipulate the probe for optimal image resolution (Fig. 5.5a, b).

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J. H. Stevenson

Probe Coupling Agents Coupling of the probe to the skin is necessary to provide a link between the transducer and the patient. The sound waves produced and received by the transducer will not pass through air. A coupling agent is required and generally consists of gel or a standoff pad.

Gel Ultrasound gel is an ideal medium that allows for coupling of the ultrasound signal without providing distortion. Gel should completely cover the probe surface but not be too excessive so as to cause one to lose grip of the probe. Bony surfaces or irregular surfaces may require additional gel to compensate for the peaks and valleys of the surface, allowing for uniform coupling. Finally, sterile gel should be utilized for ultrasoundguided injections/aspirations/needle procedures when the needle may potentially come in contact with the gel.

Standoff Pad The standoff pad is made of an acoustically transparent medium that provides a compliant surface to image bony or uneven surfaces. Standoff pads also assist in imaging shallow or sensitive areas by increasing the depth of the structures and providing a cushioned surface (Fig. 5.6).

Probe Orientation to the Patient In order to maintain consistency, the left side of the probe should correlate with the left side of the screen, while the right side of the probe should correlate with the right side of the screen. Most commercial probes will have a notch or indicator light on one side of the probe that aligns with the same side of the display, allowing for rapid detection of orientation. An important point is to ensure that both the examiner and the patient are comfortable during the procedure. The patient may be positioned on a table, recliner, or stool. The examiner should be sitting with the US monitor close and at the proper height (eye level) to comfortably perform the exam. By convention, the probe should be oriented cephalad when in a sagittal or coronal plane. When the transducer is in the axial plane, the left side of the probe should align with the right side of the patient’s body; conversely, the right side of the probe should align with the left side of the patient’s body. Some clinicians may reverse this depending on their hand dominance during certain procedures. A simple way to check for probe orientation related to the patient and the screen is to gently tap one side of the probe (with gel applied)

Fig. 5.6  Standoff pad

with a finger and look at the screen to determine probe orientation. Any orientation is acceptable as long as it is consistent, marked, and documented.

Probe Axis to the Imaged Structure Once the probe is placed on the skin, the probe will need to align with the long or short axis to the structure one is visualizing. The long (or longitudinal) axis is along the plane that parallels the greatest length of the structure, while the short (or transverse) axis runs perpendicular to the long axis and parallel to the greatest width of the structure (Fig. 5.7a, b). Figure 5.7a is an ultrasound screenshot corresponding to the long-axis probe placement over the quadriceps tendon demonstrated in Figs. 5.5a and 5.7b is an ultrasound screenshot corresponding to the transverse probe placement over the quadriceps tendon demonstrated in Fig. 5.5b.

Probe Manipulations Once on the skin, the ultrasound probe can be manipulated along any of its three axes of movement (X, Y, Z axis) to facilitate proper image acquisition. Key to image acquisition is the centering of the object desired and optimizing the ultrasound probe, so the beam is aimed perpendicular to the structure. The manipulation of the probe is particularly important when imaging curved or irregular structures. The five probe planes of manipulation as defined by the American Institute of Ultrasound in Medicine are listed below: • Sliding: translates the probe along the length or width to the structures without rocking or tilting the probe. This allows visualization of the structure in length as well as width (Fig. 5.8a, b).

5  Tissue Scanning

a

19

b

Fig. 5.7 (a, b) Long- and short-axis views

• Rocking: tilting (heel-toe movement) of the probe to one edge or the other (Fig. 5.8c, d). This is helpful when there is a narrow window of imaging, and adjacent structures are to be centered or visualized. Rocking may also facilitate extending the field of view, such as in the cephalic or caudal direction. A common example of rocking is utilized to visualize the proximal biceps tendon that runs in a deep to superficial direction as it passes through the bicipital groove. • Tilting: the side-to-side movement of the probe to bring additional planes of tissue into focus without sliding the probe (Fig. 5.8e, f). • Rotating: movement of the probe in clockwise or counterclockwise movement. Rotating facilitates obtaining the long- and short-axis views of structures (Fig. 5.8g, h). • Compression: pressing down with the probe. Compressible structures such as veins or bursa fluid will decrease or disappear with compression. Compression also allows deeper structures to appear more superficial. Finally, compression may allow proper contact between the probe and patient to allow clear visualization on curved or irregular structures (Fig. 5.8i).

Focusing/Knobology Focusing may be done prior to placing the probe on the skin if the ultrasound machine has appropriate presets for the structures imaged (i.e., shoulder, knee, wrist). Conversely, focusing may occur manually after the probe has been placed on the skin. A thorough understanding of the controls and their appropriate settings (“knobology”) is another key element in obtaining an accurate and optimal image. Knobology is discussed in detail in Chap. 4.

Ultrasound Imaging Artifact Numerous ultrasound artifacts can occur and affect the proper imaging and interpretation of anatomic structures. These often occur due to the change of sound propagation through different tissue densities as well as alterations in the path taken by the US beam. An understanding of these artifacts and why they occur will enhance one’s ability to properly interpret ultrasound images.

Anisotropy Anisotropy is the property of tendons, nerves, and muscle to display a different appearance depending upon the angle the ultrasound signal is directed (insonation). When an ultrasound sound beam is at an angle less than 85°, the majority of the sound waves will not reflect back to the transducer. This results in a normally hyperechoic (bright) structure appearing hypoechoic (dark). Tendons exhibit the greatest amount of anisotropy, and the loss of the normal tendon fibrillar structure may be misinterpreted as a tear or area of tendinosis. The operator can correct the anisotropy by angling the probe sound waves perpendicular to the structure with the maneuvers described above. Figure  5.9a shows anisotropy of the flexor tendons in the carpal tunnel, and Fig. 5.9b shows anisotropy resolved using tilting.

Acoustic Shadowing Acoustic shadowing is the attenuation of sound waves due to very dense substance that reflects nearly all the sound waves. Figure 5.10 shows acoustic shadowing from the scaphoid in the volar wrist. This results in a lack of visualization deep to

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a

b

c

d

e

f

g

h

i

Fig. 5.8 (a–i) Example of five probe movements: sliding, rocking, tilting, rotating, compression

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5  Tissue Scanning

a

b

Fig. 5.9 (a, b) Example of anisotropy (a), anisotropy resolved (b)

Fig. 5.11  Example of acoustic enhancement Fig. 5.10  Example of acoustic shadowing

the structure. Commonly, this can occur from bone, foreign bodies, and intratendinous/muscular calcifications.

Acoustic Enhancement Acoustic enhancement results from sound waves passing through anechoic (black-appearing) structures (fluid). The structures deep to the fluid then appear more echogenic than the same tissue on either side of the fluid. Figure 5.11 shows acoustic enhancement of the biceps tendon (BT).

Reverberation Artifact Reverberation artifact results from sound waves reflecting back and forth between the surface of the transducer and a highly echogenic structure. The resulting image is one of evenly spaced lines of the structure at increasing depths. Needle guidance is a common scenario in which reverberation artifact can occur when the needle is near perpendicular to the probe (Fig. 5.12).

Fig. 5.12  Example of reverberation artifact

Refraction Artifact Refraction artifact is also known as edge shadowing and occurs distal to the edges of curvilinear structures. Sound waves impacting a curved surface are refracted/bent from

J. H. Stevenson

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their original direction, resulting in falsely hypoechoic edge shadowing distally (Fig. 5.13).

Ultrasound Imaging of Normal Tissue The understanding and identification of normal tissue architecture is fundamental to performing musculoskeletal ultrasound. The following is a brief overview of the different tissue characteristics that help differentiate one from the other.

Skeletal Muscle Skeletal muscle is viewed as a heterogeneous structure with hypoechoic muscle fiber bundles interspersed with hyperechoic stromal connective tissue (perimysium). On long-axis view, this will give a pennate appearance similar to barbs converging on a feather (Fig.  5.14a, gastrocnemius and

soleus muscles, long axis). The hyperechoic stromal connective tissue will converge toward the end of the muscle into the muscle tendon. Muscle on cross section is displayed as a “starry night” appearance, with wavy, hyperechoic connective tissue interspersed with the hypoechoic muscle fibers (Fig. 5.14b, gastrocnemius and soleus muscles, short axis).

Tendons Tendons are displayed as a mixture of bright echogenic tendon fibers interspersed with hypoechoic surrounding connective tissue in a parallel course. On long-axis view, this results in a linear fibrillar appearance. Tendons imaged on short-axis view will demonstrate hyperechoic collagen bundles seen in short-axis view interspersed between hypoechoic connective tissue. Because of the compact fibrillar structure of tendons, they can suffer from anisotropy artifact if visualized at an angle less than perpendicular (Fig. 5.15a, Achilles tendon in long axis; Fig. 5.15b, Achilles tendon in short axis).

Ligaments Ligaments are visualized as bright hyperechoic linear fibrils with linear areas of hypoechoic connective tissue (Fig. 5.16). Ligaments have a similar appearance to tendons but tend to be more compact, with their individual collagen fibrils more closely aligned. Ligaments may also suffer from anisotropy artifact when imaged.

Fascia

Fig. 5.13  Example of refraction artifact

a Fig. 5.14 (a, b) Example of skeletal muscle, long and short axis

Fascia is displayed as hyperechoic (bright) structure (Fig.  5.17, fascia in hamstring). Fascia thickness can vary depending on the structure and location imaged.

b

5  Tissue Scanning

a

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b

Fig. 5.15 (a, b) Example of tendon, long and short axis

Fig. 5.16  Example of ligament (MCL – medial collateral ligament of knee)

Fig. 5.18  Example of subcutaneous tissue

this will be the subcutaneous fat displayed as a hypoechoic (dark) adipose tissue irregularly interspersed with hyperechoic connective tissue (Fig. 5.18, subcutaneous tissue over medial gastrocnemius).

Cortical Bone Cortical bone is shown as hyperechoic (bright) linear line with posterior acoustic shadowing due to complete reflection of the ultrasound beam (Fig. 5.19 a, transverse view of hyperechoic midshaft radius with acoustic shadowing, and Fig. 5.19b, longitudinal view of hyperechoic midshaft radius).

Peripheral Nerves Fig. 5.17  Example of fascia

Subcutaneous Tissue Subcutaneous tissue will be displayed as a hyperechoic (bright) superficial structure (epidermis and dermis). Deep to

Peripheral nerves are displayed as larger hypoechoic nerve fascicles embedded within smaller hyperechoic interfascicular epineurium. Peripheral nerves visualized on short-axis view will display the characteristic “honeycomb” appearance. On long-axis view, they will be displayed as a “train track” structure (Fig.  5.20a, median nerve, short axis; Fig. 5.20b, median nerve, long axis).

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a

b`

Fig. 5.19 (a, b) Example of cortical bone

a

b

Fig. 5.20  Example of peripheral nerves, short (a) and long (b) axis

Bursa Bursae that are not inflamed will be seen as a small strip of anechoic (black) structure surrounded by hyperechoic (bright) peribursal fat. When distended, it will have a larger area of anechoic or hypoechoic (dark) signal and may be filled with septations and synovial debris (Fig.  5.21, distended olecranon bursa with debris).

Articular Cartilage Articular cartilage is seen as an anechoic (black) layer overlying the periosteum (Fig.  5.22, femoral trochlear cartilage).

Advanced Ultrasound Techniques A fundamental advantage of ultrasound is the dynamic nature of the exam where images are obtained in real time.

This allows for many advantages over static imaging ­techniques such as plain radiographs, CT, and MRI.  The interaction between examiner, probe, and patient can greatly facilitate a dynamic exam that will allow for additional diagnostic information.

Sono-palpation Sono-palpation describes the interplay between the pressure applied by the transducer and the pain perceived by the patient. This allows correlating areas of tenderness with underlying pathology. Sono-palpation can also involve the dynamic palpation of structures to view whether they are solid or fluid filled. Solid structures will maintain their shape while filled with fluid; structures such as an effusion or bursa will compress and even disappear with compression (Fig. 5.23a, olecranon bursa with minimal compression [note debris in bursa]; Fig.  5.23b, same olecranon bursa with more compression).

5  Tissue Scanning

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Fig. 5.22  Example of articular cartilage Fig. 5.21  Example of bursa

a

b

Fig. 5.23 (a, b) Bursa, without and with probe compression

Stress Views Stress views describe the ability to image an area while dynamically providing a stress to the structure. Examples include imaging of the ulnar collateral’s anterior band while providing a valgus stress to the elbow. The integrity of the ligament can be viewed in real time as well as the amount of jointspace widening with a valgus stress (Fig. 5.24a, stress view, medial elbow, UCL tear, affected side [note gapping of joint]; Fig. 5.24b, stress view, medial elbow, and unaffected side).

Dynamic Views Dynamic views describe the ability to image structures while moving the affected region/joint through an active or passive range of motion. An example includes watching for signs of

rotator cuff/bursa impingement while passively abducting the shoulder under real-time ultrasound imaging (Fig. 5.25). Another example is having the patient actively contract an injured muscle to look for muscle widening consistent with a tear.

Split-Screen Comparison Split-screen comparison allows for the rapid capture of comparison views on ultrasound imaging between affected and unaffected sides of the body. The views may be saved as an image on one half of the screen with a comparison view saved to the other half. This allows for rapid comparison and analysis including measurements. The ability to easily perform comparison views is an important differentiator with MRI.

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a

b

Fig. 5.24 (a, b) Stress view of the ulna collateral ligament demonstrating joint-space widening

Fig. 5.25  Dynamic US impingement test

Clinical Exercise 1. Demonstrate the proper technique to scan a body part using each transducer that your machine has. Make sure that you “anchor” the probe using your fourth and fifth finger. Repeat this using both your right and left hand. 2. Demonstrate or describe how you would position yourself, the patient, and the ultrasound machine to scan a shoulder, wrist, knee, and hip. 3. Demonstrate and, if possible, record an image while doing the following probe manipulations: • Sliding • Rocking • Tilting • Rotating • Compressing 4. Identify and record an image of the following (when recording the image, include long- and short-axis views;

also adjust gain and depth, and manipulate the probe to show anisotropy where applicable): • Muscle • Tendon • Nerve • Ligament • Bone • Bursa • Articular cartilage 5. Please obtain a large chicken breast or turkey breast. It is acceptable to leave the breast on the carcass or remove it on the underside of the breast (leave “skin side” intact). Bury in the breast (1) grape, (2) needle, (3) and one of the small bones from the carcass. If possible, place these objects at different depths. • Identify these objects (it is best to have someone else insert the above items, so the scanner is unaware of where the objects are). • Demonstrate acoustic shadowing, acoustic enhancement, reverberation artifact, refraction artifact, and sono-palpation. • The breast can be saved and used for other clinical exercises (see Chap. 5).

Suggested Reading Finnoff JT, Hall MM, Adams E, Berkoff D, Concoff AL, Dexter W, Smith J. American Medical Society for Sports Medicine. American Medical Society for Sports Medicine position statement: interventional musculoskeletal ultrasound in sports medicine. Clin J Sport Med. 2015;25(1):6–22. Forney MC, Delzell PB.  Musculoskeletal ultrasonography basics. Cleve Clin J Med. 2018;85(4):283–300. Spicer PJ, Fain AD, Soliman SB.  Ultrasound in Sports Medicine. Radiol Clin North Am. 2019;57(3):649–56. Taljanovic MS, Melville DM, Scalcione LR, Gimber LH, Lorenz EJ, Witte RS.  Artifacts in musculoskeletal ultrasonography. Semin Musculoskelet Radiol. 2014;18(1):3–11.

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Hand and Fingers Matthew C. Bayes

Approach to the Joint

contributes to the lateral band, which attaches laterally on the distal phalanx. The extensor hood, made up of transversely oriented sagittal bands at the MCP joint, stabilizes the extensor tendon. The MCP and IP joints are synovial joints with synovial pouches proximal to the joint line on both the dorsal and volar aspects. The capsule is thicker on the volar aspect, where the volar plate reinforces it. The volar plate is made of thick fibrocartilage and limits finger hyperextension. The proper collateral and accessory collateral ligaments are two strong ligaments at both the ulnar and radial aspects of the joints. They reinforce and thicken the capsule on both sides of the joint. In the thumb, the ulnar collateral ligament (UCL) of the MCP joint is covered by the dorsal aponeurosis of the adductor pollicis muscle that inserts onto the dorsal aspect of the joint. For anatomical relationships, see Fig.  6.1 Cross-­ sectional anatomy—sagittal; Fig.  6.2 Cross-sectional anatomy—axial; Fig.  6.3 Volar anatomy; and Fig.  6.4 Dorsal anatomy.

The hand and fingers have many easily identifiable soft tissue and bony structures in a relatively small area, making ultrasound a useful diagnostic tool. There are 14 phalanges and 5 metacarpal bones. The volar aspect of the fingers includes two flexor tendons: the flexor digitorum superficialis and flexor digitorum profundus. The profundus tendon lies deep and inserts on the proximal aspect of the distal phalanx, while the superficialis tendon rides superficial and splits at the proximal interphalangeal (PIP) joint, with a branch on either side of the profundus tendon, until its insertion on the middle phalanx. Throughout their course, starting at the metacarpophalangeal (MCP) joint, several pulleys, numbered A1 to A5 from proximal to distal, secure both flexor tendons. These pulleys prevent bowstringing of the tendons with flexion. The dorsal aspect of the phalanges contains one extensor tendon: the extensor digitorum. This attaches to the middle phalanx but also

Fig. 6.1 Cross-sectional anatomy—sagittal

MCP MC

PIP

DIP

Prox P. MID. P. O. P.

A1

Profundus

Superficialis

A2

Volar plate

A3

Flexor digitorum superficialis

A4

Flexor digitorum profundus

M. C. Bayes (*) Founding Partner Bluetail Medical Group, Chesterfield, MO, USA © Springer Nature Switzerland AG 2021 J. M. Daniels, W. W. Dexter (eds.), Basics of Musculoskeletal Ultrasound, https://doi.org/10.1007/978-3-030-73906-5_6

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M. C. Bayes Collateral ligament

Extensor Phalanx digitorum

Phalanx

Flexor digitorum profundus Flexor digitorum superficialis

Digital artery Digital nerve Annular pulley

Fig. 6.2  Cross-sectional anatomy—axial

Distal phalanx

Middle phalanx

Flexor digitorum profundus Collateral ligament Flexor digitorum superficialis

Proximal phalanx

Extensor digitorum

Collateral ligament

Fig. 6.4  Dorsal anatomy

to maintain contact between the probe surface and the skin near the bony surfaces of the hand and fingers. Most ultrasound machines have preset musculoskeletal settings to improve superficial structure visualization. As one is getting started imaging, it is recommended to use these presets for optimal evaluation of the hand and fingers. Ultrasound machines now commonly have several improved features. These can include extended field of view capabilities aimed to help visualize structures larger than one screen’s view (such as a longitudinal view of a tendon throughout its course to insertion), steering functions to aid in needle guidance, and color Doppler flow to better evaluate vascular structures and hyperemia. The optimal way to evaluate the hand and fingers is with the patient in a seated position. Typically, the dorsal aspect is evaluated first, with the hand placed on a small block or cylinder with the fingers hanging over its edge to aid in dynamic imaging during extension. Copious use of ultrasound gel is preferable to maintain skin contact. An evaluation of the hand and fingers may be focused on the pathologic region, but it is wise to master the complete evaluation to learn normal variants vs. pathologic findings. Comparison with the contralateral hand is also useful to compare normal findings with pathology.

Interosseus muscles

Common Pathologic Conditions Metacarpal

Fig. 6.3  Volar anatomy

Probe, Machine Setting, and Technique A high-frequency transducer of 10–15 MHz is optimal for the hand and fingers owing to the superficial nature of the structures. A linear array probe is best for resolution, and a “hockey stick” probe, which has a small surface footprint, is beneficial

 xtensor Tendon Tear, Extensor Avulsion E Fracture/Mallet Finger During evaluation of a tendon over the phalanges, long-axis planes are useful for demonstrating focal areas of tendon swelling and for evaluating tendon gliding with dynamic examination. Ultrasound is useful to identify full-thickness tendon tears and to locate the retraction of the tendon end. Partial tears are seen as focal hypoechoic (dark) areas within the tendon. Most extensor tendon injuries occur due to sudden flexion on an actively extending distal phalanx, often avulsing the tip of bone with the tendon. As a result, the fingertip cannot be extended, causing a mallet finger deformity (Fig. 6.5 and Table 6.1).

6  Hand and Fingers Fig. 6.5  Common finger pathology

29 2

1

1– Mallet Finger 2 – Boutonniere Finger 3 – Jersey Finger 4 – Gamekeeper Thumb 5 – Volar Plate 6 – Tenosynovitis 7 – Climber’s Finger 8 – Trigger Finger 9 – MCP Arthritis

5

3

8

7

4

6 9

Central Slip Tear/Boutonniere Deformity A boutonniere deformity occurs when the central slip of the extensor tendon tears at its insertion on the base of the middle phalanx. Longitudinal imaging shows the disruption in the tendon at the level of the PIP joint. The lateral slips of the extensor tendon move below the midline axis of the PIP joint to become PIP flexors. Because the lateral slips remain attached to the base of the distal phalanx, they lead to hyperextension of the distal IP joint (see Fig.  6.5 and Table 6.1).

Flexor Tendon Tear/Jersey Finger The flexor digitorum superficialis and/or the flexor digitorum profundus can tear. Avulsion of the flexor digitorum profundus from its distal insertion can occur as a result of a forced passive hyperextension injury on an actively flexed finger. This occurs usually during contact sports such as football or rugby and is commonly referred to as “jersey finger.” This can cause an avulsion of a bony fragment from the palmar aspect of the distal phalanx, which commonly retracts (see Fig. 6.5 and Table 6.2).

Volar Plate Injury Volar plate injuries are typically due to hyperextension trauma of the joint. A long-axis view of the joint will show a

hypoechoic cleft in the palmar plate if it is a full-thickness tear, just deep to the flexor tendon (see Fig. 6.5 and Table 6.2).

Tenosynovitis Tenosynovitis is characterized by distention of the synovial sheath around the tendon. If traumatic, a careful search for a hyperechoic structure within the tendon sheath should be performed, as surgical removal is mandatory if a foreign body is found lying within a synovial sheath. Long-axis view of the sheath fluid is best done over the metacarpal head owing to the more superficial course of the flexor tendons. Short-axis view gives a clear assessment of the volume of tendon sheath fluid (see Fig. 6.5 and Table 6.2).

Annular Pulley Tear/Climber’s Finger Acute tears of the annular pulleys are mainly due to maximal resisted flexion of the fingers, a common injury in rock climbers. The A2 and A4 pulleys are most commonly affected. A missed diagnosis can lead to a flexion contracture of the PIP joint and secondary osteoarthritis. The easiest way to diagnose this is by viewing a subluxing flexor tendon that instead of coursing along the concavity of the phalanges lies at a variable distance from the volar cortex. This is best done by scanning during active flexion while the examiner tries to extend it by gently pushing the fingertip (see Fig.  6.5 and Table 6.2).

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M. C. Bayes

Table 6.1  Hand and finger: dorsal view of finger Patient position Extensor tendon Patient seated, hand resting with fingers extended, dorsal side up

Transducer position and description

Long-axis view Probe over DIP, align with longitudinal extensor tendon fibers

Short-axis view Probe over distal MP

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6  Hand and Fingers

Picture of scan and labeled structures

Pearls/pitfalls If avulsion is present, must identify and treat appropriately to avoid mallet finger deformity at the DIP joint May place hand on a small cylinder with fingers over its edge to aid in dynamic testing of extension

Labeled structures ET—extensor tendon and insertion NAIL—fingernail and bed DP—distal phalanx MP—middle phalanx DIP—distal interphalangeal joint

Short-axis or transverse view helpful to look at possible tendon ruptures

Labeled structures ET—extensor tendon MP—middle phalanx

(continued)

M. C. Bayes

32 Table 6.1 (continued) Patient position Extensor tendon central slip Similar positioning as above

Transducer position and description

Long-axis view Similar to extensor tendon, probe is long axis over dorsal PIP/proximal aspect of middle phalanx

Short-axis view Similar to DIP, probe is short axis over distal proximal phalanx

6  Hand and Fingers

Picture of scan and labeled structures

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Pearls/pitfalls If full-thickness central slip tear, must manage correctly to avoid boutonniere deformity due to volar migration of the lateral bands of the extensor tendon

Labeled structures ET—extensor tendon PP—proximal phalanx MP—middle phalanx PIP—proximal interphalangeal joint

Labeled structures ET—extensor tendon PP—proximal phalanx

(continued)

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M. C. Bayes

Table 6.1 (continued) Patient position

Transducer position and description

Long-axis view Probe long axis to tendon over the MCP joint

Short-axis view Probe short axis over distal metacarpal

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6  Hand and Fingers

Picture of scan and labeled structures

Labeled structures MC—metacarpal PP—proximal phalanx MCP—metacarpophalangeal joint ET—extensor tendon

Labeled structures MC—metacarpal ET—extensor tendon

Pearls/pitfalls

M. C. Bayes

36 Table 6.2  Hand and finger: palmar or volar view of the finger Patient position Flexor digitorum profundus Patient seated, with volar aspect of hand up

Transducer position and description

Long-axis view Probe is long axis centered over the flexor tendon and underlying volar plate at the PIP joint

Short-axis view Probe is short axis to tendon and middle phalanx

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Picture of scan and labeled structures

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Pearls/pitfalls Tendon visible inserting at distal phalanx If full-thickness tear of FDP, the patient unable to actively flex the DIP joint Look for proximally migrated avulsion fragment/torn tendon; may migrate into the hand. Surgical referral is necessary

Labeled structures FDP—flexor digitorum profundus MP—middle phalanx DP—distal phalanx DIP—distal interphalangeal joint

Labeled structures FDP—flexor digitorum profundus MP—middle phalanx

(continued)

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M. C. Bayes

Table 6.2 (continued) Patient position Flexor digitorum superficialis Patient seated, with volar aspect of hand up

Transducer position and description

Long-axis view Probe is long axis centered over the flexor tendon, at the PIP joint

Long-axis view Probe is long axis to tendon Mid shaft phalanx

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Picture of scan and labeled structures

Pearls/pitfalls Tendon visible inserting in the middle phalanx If full-thickness tear of FDS, the patient is unable to actively flex the PIP joint Look for the proximally migrated avulsion fragment/torn tendon; may migrate into the hand. Surgical referral is necessary

Labeled structures FDS—flexor digitorum superficialis PP—proximal phalanx MP—middle phalanx PIP—proximal interphalangeal joint

Mid shaft proximal phalanx, the FDS and FDP cross with the FS diving deep to insert on the middle phalanx with the FDP travelling distally to insert on the distal phalanx

Labeled structures FDS—flexor digitorum superficialis FDP—flexor digitorum profundus PP—proximal phalanx (continued)

M. C. Bayes

40 Table 6.2 (continued) Patient position

Transducer position and description

Short-axis view Probe is short axis Mid shaft proximal phalanx Volar plate Patient seated, with volar aspect of hand up

Long-axis view Probe is long axis centered over the volar plate of PIP joint

6  Hand and Fingers

Picture of scan and labeled structures

41

Pearls/pitfalls Volar plate is identified as structure spanning the two phalanges of the DIP joint

Labeled structures PP—proximal phalanx FDS—flexor digitorum superficialis

Labeled structures VP—volar plate PP—proximal phalanx MP—middle phalanx PIP—proximal interphalangeal joint

(continued)

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Table 6.2 (continued) Patient position Annular pulley Patient seated, with volar aspect of hand up

Transducer position and description

Long-axis view Probe is long axis over the proximal phalanx A1 pulley Patient seated, with volar aspect of hand up

Long-axis view Probe is long axis over the MCP joint in the palm

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Picture of scan and labeled structures

Pearls/pitfalls Annular pulley injury confirmed with active resisted flexion causing obvious separation of the flexor tendon from the proximal phalanx; confirmed with comparison of adjacent finger

Labeled structures FT—flexor tendon AP—annular pulley PP—proximal phalanx MP—middle phalanx PIP—proximal interphalangeal joint

Hypoechoic thickening of the A1 pulley with mild inferior deviation of the flexor tendon is indicative of trigger finger. Dynamic evaluation may show tendon catching in the pulley

Labeled structures FDS—flexor digitorum superficialis MC—metacarpal PP—proximal phalanx MCP—metacarpophalangeal joint A1P—A1 pulley

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M. C. Bayes

A1 Pulley Thickening/Trigger Finger

Dupuytren Contracture

Chronic repetitive movement of the finger may lead to thickening of the A1 pulley and impingement of the involved tendon in the narrowed digital tunnel. A long-axis view at the level of the MCP joint shows hypoechoic thickening of the A1 pulley and mild deviation of the flexor tendon (see Fig. 6.5 and Table 6.2).

Dupuytren contracture appears as a palmar hypoechoic thickening of the palmar fascia adjacent to the flexor tendon in the palm, usually near the distal metacarpal [1]. The hypoechoic region can occasionally show hyperemia or calcification.

MCP/IP Joint Arthritis Ultrasound is highly sensitive in detecting joint effusion and small osteophytes and bony erosions that are often missed on standard radiographs. Effusion is visible as synovial distention with underlying hypoechoic fluid (see Fig.  6.5 and Table 6.3).

First CMC Joint Arthritis The first CMC is commonly affected with osteoarthritis. This joint can show subluxation of the metacarpal bone, capsular thickening, and effusion on ultrasound. Doppler ultrasound identification of the radial artery as it passes near to the dorsal joint is important prior to any attempted injection.

Collateral Ligament Tear/Gamekeeper’s Thumb Assessment of the collateral ligaments of the second through fifth MCPs can be difficult. The most common and important collateral ligament injury is a tear of the UCL at the thumb MCP joint. An acute injury is referred to as a skier’s thumb, while a chronic injury is referred to as a gamekeeper’s thumb. The mechanism is excessive flexion and valgus stress, which leads to distal tear of the ligament (see Fig. 6.5 and Table 6.3). US images should be obtained at rest and during cautious valgus stress to assess for increased radial subluxation of the proximal phalanx. Care should be taken to avoid causing displacement of a non-displaced ligament tear (Table 6.4). With a first MCP UCL tear, care should be taken to differentiate a sesamoid bone from a cortical avulsion of the base of the proximal phalanx. Seeing the rounded appear-

6  Hand and Fingers

ance of the sesamoid bone will accomplish this. A longaxis image at the level of the metacarpal head is used to detect a displaced proximal ligament fragment (Stener lesion) over the proximal edge of the adductor pollicis aponeurosis. The torn end of the ligament bunches up and gives the appearance of a “yo-yo on a string.” This lesion has surgical ramifications and is not to be missed (see Fig. 6.5 and Table 6.4).

Foreign Body Penetrating injuries to the hand should be imaged to rule out the presence of a foreign body. Ultrasound is relatively cheap, safe, and easy to perform and shows dynamic movement to identify a foreign body. Most foreign bodies are hyperechoic; some may have a posterior acoustic shadow [2].

Ganglion Cyst Ganglion cysts are benign collections of thick/mucinous fluid. Like other fluid-containing structures, ganglia are typically anechoic with well-defined walls [3]. They may contain septae and are non-compressible, without hyperemia or Doppler flow signal. Most ganglion cysts are found in the dorsal wrist. In the hand they can appear adjacent to an

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osteoarthritic interphalangeal joint, or along a flexor tendon sheath near the MCP joint. Use of Doppler to identify any adjacent vessel is vital prior to aspiration, as these are commonly adjacent to an artery.

Red Flags Failure to correctly diagnose an extensor tendon avulsion fracture can result in a permanent mallet finger deformity with loss of extension at the DIP joint. Missing an extensor tendon central slip tear at its insertion on the base of the middle phalanx can lead to a boutonniere deformity with a fixed hyperextended DIP joint and flexed PIP joint. A tear of the insertion of the flexor digitorum profundus that is missed can lead to worsening proximal retraction of the free end of the tendon from its insertion point, making repair more difficult or impossible. In the evaluation of a thumb MCP joint UCL injury, one must take care not to use excessive force during dynamic testing. If one is not careful, the dynamic test can inadvertently lead to ligament displacement, which means transforming a noncomplicated tear into a displaced lesion requiring surgery. Also, missing a displaced ligament rupture (Stener lesion) will lead to permanent instability and degenerative changes of the MCP joint. A missed annular pulley tear diagnosis, such as climber’s finger, can lead to permanent flexion contracture of the IP joint and secondary arthritis.

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Table 6.3  Hand and finger: evaluation of the MCP joint Patient position MCP Patient seated, with dorsal aspect of hand up

Transducer position and description

Long-axis view Probe is long axis over the MCP joint

6  Hand and Fingers

Picture of scan and labeled structures

Labeled structures MCP—metacarpophalangeal joint PP—proximal phalanx MC—metacarpal SPUR—osteophyte

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Pearls/pitfalls Osteophytes, synovial distention, and effusion are all symptoms of arthritis

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Table 6.4  Hand and finger: thumb Patient position UCL of thumb MCP joint Patient seated, hand holding a rolled-up towel, thumb slightly abducted. Then examiner may apply gentle valgus stress

Transducer position and description

Probe is long axis over the MCP joint to provide a coronal view (long axis to UCL)

Long-axis view Stress view of UCL, probe same orientation

6  Hand and Fingers

Picture of scan and labeled structures

Normal UCL Labeled structures MC—metacarpal 1 STP—proximal first phalanx MCP—metacarpophalangeal joint UCL—ulnar collateral ligament

Chronic tear UCL, MCP opening with osteophyte Labeled structures MC—metacarpal PP—proximal phalanx MCP—metacarpophalangeal joint

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Pearls/pitfalls When evaluating for possible UCL tear at the thumb MCP joint, the examiner must take care to first evaluate under ultrasound, if a full-thickness tear is easily visible. The examiner may apply gentle valgus stress to the MCP joint to assess for laxity and radial subluxation of the proximal phalanx on the metacarpal. However, be careful when stressing the joint to avoid displacing a proximally retracted UCL fragment under the adductor aponeurosis (Stener lesion) Comparison to the contralateral side is important when assessing joint laxity In long-axis view, full tear appears as gap in UCL; proximal retraction of UCL fragment appears balled up/hyperechoic with overlying visible adductor aponeurosis

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M. C. Bayes

Pearls and Pitfalls

References

Anisotropy must be avoided when evaluating for tendinosis or tendon tears. A hypoechoic-appearing tendon may in fact be normal; the hypoechoic appearance may be due to the angle of the sound beam with relation to the structure being evaluated. This can be ruled out by moving the transducer so as to change this angle while evaluating the tendon for a more normal appearance. Positioning is key during the ultrasound examination. It is recommended to have both the patient and physician seated for the hand and finger evaluation, starting with the dorsal hand and moving in a systematic fashion. Having a small ball or cylinder to rest the fingers on is crucial. Copious use of Doppler imaging to mark vascular structures is key prior to any injection.

1 . Morris, et al. J Ultrasound Med. 2019;38(2):387–92. 2. Ipaktchi, et al. Patient safety in surgery. 2013;7:25. 3. Cardinal, et al. Radiology. 1994;193:259–62.

Suggested Reading Bianchi S, Martinoli C.  Ultrasound of the musculoskeletal system. New York: Springer; 2007. Daniels JM, Zook EG, Lynch JM.  Hand and wrist injuries: Part I. Nonemergent evaluation. Am Fam Physician. 2004a;69(8):1941–8. Daniels JM, Zook EG, Lynch JM.  Hand and wrist injuries: Part II. Emergent evaluation. Am Fam Physician. 2004b;69(8):1949–56. Jacobson J. Fundamentals of musculoskeletal ultrasound. Philadelphia: Elsevier; 2007. McNally E.  Practical musculoskeletal ultrasound. Philadelphia: Elsevier; 2005.

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Wrist Joseph J. Albano

Approach to the Joint

Dorsal Aspect of the Wrist

Volar Aspect of the Wrist

The patient can remain seated and place the hand on the table, with the hand and wrist halfway between pronation and supination and the thumb toward the ceiling. Then place the probe on the radial styloid, transverse, or short axis, to the radius. Scan the first dorsal compartment. This includes the abductor pollicis longus [APL] (ventral) and extensor pollicis longus [EPL] (dorsal). The APL should be followed distally to the scaphoid to assess its accessory tendons. The radial artery and sensory branch of the radial nerve can also be evaluated in this position. The patient then turns the wrist, so the palm is facing downward to view the second dorsal compartment. The extensor carpi radialis longus (ECRL) and the extensor carpi radialis brevis (ECRB) are evaluated by moving the probe, transverse (short-axis position), toward the radial styloid. The probe is then swept (slowly) proximally to view where the second compartment intersects with the first dorsal compartment. Tendinopathy here may indicate intersection syndrome. The probe is then brought distally to the center of the wrist over Lister’s tubercle (LT) and placed in a transverse (short-axis) position, centered over LT.  Just radial is the ECRB (second compartment), and just to the ulnar aspect of LT is the EPL, in the third dorsal compartment. The probe, still transverse, can continue to be moved in an ulnar direction, and adjacent to the EPL is the fourth dorsal compartment (extensor indicis proprius [EIP] and the extensor digitorum communis [EDC] tendons). The extensor digiti quarti, in the fifth compartment, is located between the ulna and radius. When the probe is completely over the distal ulna, it may need to be placed, short axis, on the ulnar side of the wrist to view the last extensor compartment, the extensor carpi ulnaris (ECU), a tendon that is commonly injured. The dorsal aspect of the wrist is fairly easy to scan, but at first the anatomy can be confusing. Memorization of the names of the tendons is not required at first. Each tendon can eventually be followed along its course, but to start, simply

Have the patient seated with the hand on the table in a palm­up position. The examiner can be seated on an adjustable rolling stool. It is helpful if the table is also adjustable. For procedures, a small roll can be used to support the dorsal wrist to allow easier needle access. A rolled-up towel or chucks held together with tape would suffice. Evaluate the proximal carpal tunnel first. Start with the transducer at the level of the wrist crease in a transverse (axial) position. This is short axis to the flexor tendons. Adjust the probe orientation so that one edge is over the scaphoid tubercle and the other is over the pisiform. Angle the transducer to compensate for the normal wrist contour. In addition, evaluate dynamic imaging with finger flexion and extension to demonstrate the normal motion of the tendons. Now evaluate the distal carpal tunnel by moving the transducer distally until the trapezial tubercle (on the radial side) and the hook of the hamate (on the ulnar side) are visible. Slightly adjust probe orientation to account for changes in the median nerve depth. Slight wrist flexion can also maximize the image quality. Sweep the transducer from the proximal to distal carpal tunnel, systematically examining the median nerve from the distal radius to beyond the retinaculum. Note any increase in cross-sectional area (CSA) of the median nerve or anatomic variants, such as bifid median nerve or persistent median artery. Also examine the other structures noted above. Finally, evaluate Guyon’s canal (ulnar artery, vein, and nerve) by moving the transducer medially (ulnar direction) using the pisiform bone as a landmark (see Fig. 7.1). J. J. Albano (*) Albano Clinic, University of Utah, Adjunct Instructor in Family & Preventive Medicine, University of Utah, Salt Lake City, UT, USA e-mail: [email protected]

© Springer Nature Switzerland AG 2021 J. M. Daniels, W. W. Dexter (eds.), Basics of Musculoskeletal Ultrasound, https://doi.org/10.1007/978-3-030-73906-5_7

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Median nerve

Palmaris longus

Flexor digitorum profundus

Flexor digitorum Flexor carpi superficialis ulnaris

Flexor carpi radialis Flexor pollicis longus

Ulnar artery Ulnar nerve Ulnar vein

Radial artery Radius Compartment I Abductor pollicis longus Extensor pollicis brevis Compartment II Extensor carpi radialis longus Extensor carpi radialis brevis

Compartment VI Extensor carpi ulnaris Compartment III Extensor pollicis longus

Compartment IV Extensor digitorum Extensor indicis

Compartment V Extensor digitiminimi

Fig. 7.1  Cross-sectional anatomy of the wrist

identify Lister’s tubercle, and the six compartments can easily be scanned using Table  7.1 as a guide. As you become more comfortable, evaluation of ligaments and bones is possible in this area (see Fig. 7.1).

Probe Selection and Presets Because the structures are superficial, a high-frequency linear transducer of 10–13 MHz is required. Thick transducer gel or standoff pad should be used to aid in this process. A “hockey stick” transducer can be helpful for the smaller structures, but not mandatory. If your machine has wrist or hand presets, start with those.

Common Problems I Can’t Find the Median Nerve! When imaged in the short-axis, or transverse, plane, normal peripheral nerves have a characteristic honeycomb appearance. The fascicles are hypoechoic, and the surrounding connective tissue is hyperechoic. If it is difficult to identify the median nerve, move the transducer proximally. Knowledge of the characteristic location, course, echogenicity, and anisotropy will assist in the identification. The median nerve lies superficial to the flexor digitorum profundus and superficialis tendons and deep to the flexor retinaculum. The distal end of the nerve is tapered. Do not confuse the palmaris longus tendon with the median nerve as they can appear similar. This tendon lies superficial to the

retinaculum and the nerve lies deep to it. The median nerve moves medial to lateral as it progresses distally from the proximal wrist crease. The median nerve appears relatively hyperechoic proximally and hypoechoic distally. This is secondary to the relative echogenicity of the surrounding tissue. The muscle is hypoechoic proximally, and the tendons are hyperechoic distally. In order to take advantage of the change in echogenicity of the tendons, angle the transducer to produce a hypoechoic signal in the normally hyperechoic tendons. The median nerve should remain hypoechoic.

How Do I Diagnose Carpal Tunnel Syndrome? Carpal tunnel syndrome (CTS) findings on US include an enlarged median nerve, bulging of the transverse carpal ligament, flattening of the median nerve in the distal carpal tunnel, hypoechogenecity of the median nerve, and decreased mobility. In the criteria for diagnosing CTS with US imaging, the most commonly used is the median nerve cross-­sectional area (CSA) method. There is a lack of consensus in the literature regarding the most appropriate median nerve threshold to establish this diagnosis. While scanning, keep the transducer pressure minimal during measurements in order to avoid any pressure on the nerve. Some US machines have an ellipse tool, which uses a formula to create the CSA. This indirect method is not the chosen method for median nerve CSA measurement. Direct tracing of the nerve inside the epineurium is more accurate. Using this method, Ziswiler et al. [1] derived a cutoff value of 10 mm2 and achieved a sensitivity of 82% and specificity of 87%, which approaches those of electrodi-

7 Wrist

agnostic tests. For a median nerve CSA 12 mm2, CTS can be ruled in. Klauser et al. [2] described a more accurate method. In this method, the carpal tunnel was scanned from the proximal portion (scaphoid-pisiform level) to the distal portion (trapeziumhamate level). The largest median nerve cross-sectional area (CSAc) measurement was used. The more proximal crosssectional area (CSAp) measurement was obtained in the distal forearm at the level of the proximal third of the pronator quadratus muscle. The median nerve lies between the flexor pollicis longus and flexor digitorum superficialis tendons in this location. The value for the difference between CSAc and CSAp is delta CSA. The best diagnostic discrimination was achieved using a delta CSA threshold of 2  mm2, which yielded 99% sensitivity and 100% specificity. Other studies have not demonstrated this high degree of sensitivity and specificity. The appearance of a compressed median nerve may be similar to a dumbbell or peanut with the larger swollen nerve proximally and distally and a smaller compressed nerve in the middle (see Table 7.1). If you use magnification to more easily visualize the nerve, note that this may significantly increase the measured CSA of this peripheral nerve. These changes appear to be more substantial when smaller nerves are measured (Jelsing et al. [3]). Roomizadeh [4] did a systematic review and meta-­ analysis in order to determine CSAs of the median nerve in accordance with the electrodiagnostic classification of carpal tunnel syndrome severity. The pooled analysis revealed a mean CSA of 11.64 mm2 for mild CTS, 13.74 mm2 for moderate CTS, and 16.80 mm2 for severe CTS.

 hat Are the Findings of De Quervain’s W Tenosynovitis? The APL and extensor pollicis brevis (EPB) tendons lie in the first dorsal compartment. The sheath or tendons may become irritated with repetitive motion and overuse. The classic findings of tenosynovitis should be seen, which include an anechoic (black) area surrounding the tendon and hyperemia (increased vascularity upon Doppler imaging). Tendinosis (thickened and hypoechoic [darker] tendon) or even an intrasubstance tear may be seen in these tendons.

What Is Intersection Syndrome? The APL and EPB of the first compartment cross over the ECRL and ECRB of the second compartment approximately 4 cm proximal to the Lister’s tubercle. Symptoms may occur

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at this intersection due to overuse and the associated friction of these tendons.

Red Flags Don’t ever put a needle into an anechoic space that turns out to be an artery or an aneurysm. Always check for flow using power Doppler imaging or color flow.

Pearls and Pitfalls • When first learning this wrist exam, it is helpful to practice a complete exam of all of the areas, volar and dorsal. However, during a time-crunched day at the office, it is acceptable to focus the US exam over the clinically relevant area. You will not miss a diagnosis focusing your exam in this way. • Volar. Don’t miss a scaphoid fracture! With the transducer in the longitudinal plane over the flexor carpi radialis tendon, the characteristic peanut-shaped or bilobed bony contours of the scaphoid bone are identified deep to the tendon. Fractures appear as cortical step-offs. • Dorsal scapholunate (SL) ligament tear. The SL ligament may be visualized from both the dorsal and volar directions. However, the dorsal aspect is much more easily visualized. SL tears may be seen in this view as hypoechoic areas in the hyperechoic ligament. • Look for dorsal wrist ganglion cysts superficial to the SL ligament. • The triangular fibrocartilage complex (TFCC) consists of the triangular fibrocartilage, the meniscal homologue, the ECU tendon sheath, and the volar and dorsal radiocarpal ligaments. Look at the TFCC for hypo- to anechoic areas, which signify a tear.

Clinical Exercise 1. Place the probe on the palmar side of the wrist. Identify the median nerve at the CSA between the scaphoid and pisiform and the trapezium and hook of hamate. Trace the outline of the nerve with your measurement setting and record. Now place the probe more proximally along the forearm to the pronator quadratus muscle. Take a cross-­ sectional measurement of the median nerve there and record it. 2. Place the transducer on Lister’s tubercle in a transverse (short-axis) plane. Begin moving the transducer ulnar-­ ward and radial-ward. Identify as many cross sections of the six extensor tendon compartments as possible. There

54 Table 7.1 Wrist Patient position Volar wrist: proximal carpal tunnel Patient is seated with the hand on the table with the palm up. It is helpful to place a small roll under the dorsal wrist for support. A small towel, rolled up and held together with tape, would suffice

J. J. Albano

Transducer position and description

Proximal wrist crease, short axis Place the transducer over the proximal volar crease in a short-axis position. Adjust the probe orientation so that one edge is over the scaphoid tubercle on the radial side and the other is over the pisiform on the ulnar side. Scan the median nerve, FDS, FDP, FCR, palmaris longus, and scaphoid bone For all of these areas, scan in short- and long-axis planes

Same position

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Picture of scan and labeled structures

Pearls/pitfalls Dynamic imaging with active finger flexion and extension demonstrates the normal motion of the tendons Don’t mistake the palmaris longus tendon, which lies superficial to the retinaculum, with the median nerve, which is deep to the retinaculum. In some people, the palmaris longus may not exist The radial artery and veins lie just radial to the flexor carpi radialis tendon

Labeled structures SCA—scaphoid PIS—pisiform FCR—flexor carpi radialis FPL—flexor pollicis longus MN—median nerve UA—ulnar artery FDS—flexor digitorum superficialis FDP—flexor digitorum profundus Diagnosing carpal tunnel syndrome: Short-axis measurements of the median nerve are in the cross-­sectional area (CSA) via the “trace” feature. Trace the nerve on the inside of the epineurium—CSA >1 mm2 is abnormal

Labeled structures FCR—flexor carpi radialis UA—ulnar artery MN—median nerve

(continued)

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Table 7.1 (continued) Patient position

Transducer position and description

Same orientation but slide probe proximally, following the median nerve until the pronator quadratus comes into view

Proximal wrist crease, long axis, over median nerve

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Picture of scan and labeled structures

Pearls/pitfalls Another technique that may be used requires the examiner to measure the largest cross-sectional area of the median nerve and compare it to the cross-sectional measurement of the median nerve at the level of the proximal aspect of the pronator quadratus muscle. A difference of 2 mm3 or greater indicates carpal tunnel syndrome

Labeled structures MN—median nerve PRO—pronator quadratus In the long-axis view, the median nerve is seen as “railroad tracks”

Labeled structures MN—median nerve

(continued)

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Table 7.1 (continued) Patient position

Transducer position and description

Slide probe slightly radially and distally over the FCR

Volar wrist: distal carpal tunnel Patient is seated with the hand on the table with the palm up. It is helpful to place a small roll under the dorsal wrist for support

Wrist crease, short axis Move the transducer distally until the trapezial tubercle is seen (radial) and the hook of the hamate is also seen (ulnar). Sweep the transducer from the proximal to distal carpal tunnel, systematically examining the median nerve and the tendons from the distal radius to beyond the retinaculum. Note any increase in cross-sectional area of the median nerve or anatomic variants, such as bifid median nerve or persistent median artery

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Picture of scan and labeled structures

Pearls/pitfalls Sliding the probe distally, the characteristic peanut-shaped or bilobed bony contours of the scaphoid bone are identified deep to the flexor carpi radialis (FCR) tendon. Fractures may be identified as cortical step-offs

Labeled structures FCR—flexor carpi radialis RAD—radius SCA—scaphoid TRA—trapezium Slightly adjust probe orientation to account for changes in the median nerve depth. Slight wrist flexion can also maximize the image quality Ganglion cysts are often located in this area as the transducer is moved proximal to distal

Labeled structures TRAP—trapezium HH—hook of hamate FPL—flexor pollicis longus MN—median nerve UA—ulnar artery FDS—flexor digitorum superficialis FDP—flexor digitorum profundus FR—flexor retinaculum

(continued)

J. J. Albano

60 Table 7.1 (continued) Patient position Volar wrist: Guyon’s canal Patient is seated with the hand on the table with the palm up. It is helpful to place a small roll under the dorsal wrist for support

Transducer position and description

Distal wrist crease, ulnar aspect, short axis. Move the transducer toward the ulna using the pisiform bone as a landmark

Dorsal wrist: 1st compartment The hand is placed halfway between pronation and supination, with the radius superior and 90° to the table

Short-axis view

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Picture of scan and labeled structures

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Pearls/pitfalls The ulnar artery is on the radial side of the tunnel, and the ulnar nerve is on the ulnar side next to the pisiform. There are two branches of the ulnar nerve: the superficial sensory branch and the deep motor branch. The latter lies over the hook of the hamate

Labeled structures PIS—pisiform UA—ulnar artery UN—ulnar nerve MN—median nerve FCR—flexor carpi radialis Abductor pollicis longus (APL) (volar) and extensor pollicis brevis (EPB) (dorsal) tendons over the radial styloid. The radial nerve and artery lie outside the compartment and move from ventral to dorsal over these tendons To remember the tendons in the 1st, 2nd, and 3rd compartments, moving from radial to ulna, think alternating thoughts: longus-brevis-­longus-brevis-longus (APL, EPB, ECRL [extensor carpi radialis longus], ECRB [extensor carpi radialis brevis], EPL [extensor pollicis longus]). It also goes from abductor to extensor and pollicis to carpi and back to pollicis

Labeled structures R—retinaculum RS—radial styloid APL—abductor pollicis longus EPB—extensor pollicis brevis

(continued)

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62 Table 7.1 (continued) Patient position

Transducer position and description

Long-axis view

Dorsal wrist: 2nd compartment Patient is seated with the hand on the table with the palm up. It is helpful to place a small roll under the dorsal wrist for support

Short-axis view Position the transducer slightly toward the ulna

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Picture of scan and labeled structures

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Pearls/pitfalls

Labeled structures RAD—radius MC—metacarpal EPB—extensor pollicis brevis

Labeled structures RAD—radius ECRL—extensor carpi radialis longus ECRB—extensor carpi radialis brevis

(continued)

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Table 7.1 (continued) Patient position

Transducer position and description

Short-axis view Move cranially over the ECRL and ECRB tendons until the APL and EPB of the first compartment cross over at the “intersection”

Dorsal wrist: 3rd compartment The hand is placed palm down for the 3rd to 5th compartments

Short-axis view The transducer is placed over the middorsal wrist for evaluation of these compartments

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Picture of scan and labeled structures

Pearls/pitfalls Intersection “squeaky wrist,” syndrome: tenderness and crepitation where the APL and EPB of the 1st compartment cross over the 2nd compartment at the “intersection” of the ECRL and ECRB

Short-axis view Move cranially over the ECRL and ECRB tendons until the APL and EPB of the first compartment cross over at the “intersection” Lister’s tubercle over the dorsal radius separates the second compartment (which is radial) from the third compartment (which is ulnar) Follow the extensor pollicis longus tendon from Lister’s tubercle as it crosses the ECRB and ECRL tendons to the insertion on the distal phalanx of the thumb

Labeled structures LIS—Lister’s tubercle EPL—extensor pollicis longus ECRB—extensor carpi radialis brevis ECRL—extensor carpi radialis longus

(continued)

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Table 7.1 (continued) Patient position Dorsal wrist: 3rd and 4th compartments The hand is placed palm down for the 4th to 5th compartments

Transducer position and description As above. Transducer is moved incrementally toward ulna

Dorsal wrist: 4th and 5th compartments

Continue incremental movement of probe toward ulna

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Picture of scan and labeled structures

Pearls/pitfalls

Labeled structures LT—Lister’s tubercle EPL—extensor pollicis longus (3rd compartment) EXT—extensor tendons of 4th compartment (extensor digitorum communis, extensor indicis proprius)

Labeled structures 4th—fourth compartment (extensors) ULN—ulna EDM—extensor digiti minimi (5th compartment) ECU—extensor carpi ulnaris

(continued)

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68 Table 7.1 (continued) Patient position Dorsal wrist: 6th compartment The hand is placed in extreme pronation with the thumb on the table

Transducer position and description

Short-axis view The transducer is placed over the ulnar styloid and then moved distally

Dorsal wrist: 6th compartment and TFC

Long-axis view The transducer is placed over the ulnar styloid, first in the axial plane (short axis to the ulna) and then in a longitudinal plane (long axis to ulna), and moved distally to visualize the TFC

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Picture of scan and labeled structures

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Pearls/pitfalls

Labeled structures U—ulna ECU—extensor carpi ulnaris The triangular fibrocartilage complex consists of the triangular fibrocartilage, the meniscal homologue, the ECU tendon sheath, and the volar and dorsal radiocarpal ligaments. Look at the TFCC for hypo- to anechoic areas that may signify a tear

Labeled structures ULN—ulna ECU—extensor carpi ulnaris TFC—triangular fibrocartilage RAD—radius TRI—triquetrum

(continued)

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Table 7.1 (continued) Patient position Dorsal wrist: distal radioulnar joint (DRUJ)

Transducer position and description

The transducer is placed short axis to the DRUJ and more proximal than the joint line

Dorsal wrist: scaphoid and scapholunate ligament (SLL) Palm down with ulnar deviation to assess the ligament integrity

Short-axis view From the level of Lister’s tubercle on the radius, sweep the transducer distal until the scaphoid comes into view Then move the probe to the ulnar side until the lunate is also brought into view Between these bones is the triangular SL ligament

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Picture of scan and labeled structures

Pearls/pitfalls The distal radioulnar joint (DRUJ) is best visualized with the probe in a slightly oblique short-axis position

Labeled structures ULN—ulna DRUJ—distal radioulnar joint RAD—radius 4th—fourth compartment (extensors) The SL ligament may be visualized from both the dorsal and volar directions. It is most easily seen on the dorsal short-axis view. SLL tears may be seen in this view as hypoechoic areas in the hyperechoic ligament Dorsal ganglion cysts often appear superficial to the SL ligament

Labeled structures L—lunate SC—scaphoid ECRB—extensor carpi radialis brevis SLL—scapholunate ligament 4TH, 5TH—fourth and fifth compartments with extensor tendons

(continued)

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Table 7.1 (continued) Patient position Dorsal wrist: longitudinal Palm down

Transducer position and description

The transducer is placed long axis to the extensor tendons Note: Scan from the radial to the ulnar aspect of wrist to assess entire dorsum

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Picture of scan and labeled structures

Labeled structures ER—extensor retinaculum RAD—radius SCA—scaphoid TRA—trapezium MC—metacarpal CMCJ—carpometacarpal joint DRCJ—distal radiocarpal joint MCJ—midcarpal joint

Pearls/pitfalls The extensor retinaculum has an oblique course, proximally from the radius distally past the ulna. It is hyperechoic and can measure up to 1.7 mm thick by 23 mm wide. It may appear hypoechoic due to anisotropy The radiocarpal, midcarpal, and carpometacarpal (CMC) joint recesses are evaluated for effusion, synovial hypertrophy, osteophytes, and bony erosion. Common locations for osteoarthritis are the first CMC and radiocarpal joints

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are two (first and second) compartments radial to Lister’s tubercle and the other four are ulnar.

References 1. Ziswiler HR, Reichenbach S, Vögelin E, Bachmann LM, Villiger PM, Jüni P.  Diagnostic value of sonography in patients with suspected carpal tunnel syndrome: a prospective study. Arthritis Rheum. 2005;52(1):304–11.

2. Klauser AS, Halpern EJ, De Zordo T, Feuchtner GM, Arora R, Gruber J, et al. Carpal tunnel syndrome assessment with US: value of additional cross-sectional area measurements of the median nerve in patients versus healthy volunteers. Radiology. 2009;250(1):171–7. 3. Jelsing EJ, Presley JS, Maida E, Hangiandreou NJ, Smith J, et al. Muscle Nerve. 2015;51(1):30–4. 4. Roomizadeh P, Eftekharsadat B, Abedini A, Ranjbar-Kiyakalayeh S, Yousefi N, Ebadi S, Babaei-Ghazani A. Ultrasonographic assessment of carpal tunnel syndrome severity: a systematic review and meta-analysis. Am J Phys Med Rehab. 2019;98(5):373–81.

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Elbow Heather M. Gillespie and Pierre d’Hemecourt

Approach to the Joint The elbow is divided into four regions arbitrarily for convenience. In a limited exam, not all of the areas need to be imaged. These are the anterior, medial, lateral, and posterior regions. Examination of these areas is most easily done in the seated position but may be performed in the supine (lying down, face up) position. When interventional procedures are done, they are best done in the supine position. When the patient is seated, the involved arm is next to the stretcher or examining table. Both patient and clinician are optimally on stools with rollers, with the clinician stool slightly more elevated. This allows the clinician to make slight adjustments to positions of both chairs. The clinician is facing the patient with the ultrasound unit on the opposite side of the imaged elbow. When the patient is supine, the clinician is on the side of the affected elbow with the ultrasound unit on the opposite side of the bed facing the clinician. The elbow may be placed on a small pillow or folded towel. The anterior elbow is viewed with the elbow extended or slightly flexed. In this position, dynamic imaging of the anterior recess with flexion and extension may be performed, looking for excess intra-articular fluid. Pronation and supination may be used to visualize the distal biceps region. The medial elbow is visualized with an abducted and externally rotated forearm (supination). Elbow flexion is variable by patient comfort but is usually about 30°. The lateral elbow is imaged with the arm adducted and internally rotated (fully pronated, palm down). Elbow flex-

H. M. Gillespie (*) Maine Medical Partners Orthopedics and Sports Medicine, South Portland, ME, USA e-mail: [email protected] P. d’Hemecourt Division of Sports Medicine, Primary Care Sports Medicine, Director of Sports Ultrasound Program, Boston Children’s Hospital, Boston, MA, USA e-mail: [email protected]

ion is between 20° and 40° on the table. This may also be accomplished by having both hands together with thumbs up and elbows fully extended. The posterior elbow is visualized in several positions. Seated, the shoulder is flexed forward just above 90° with a fully flexed elbow. The cubital tunnel may be visualized. Alternately, the patient may extend the arm behind him with the elbow flexed at 90° and the palm down on the table. The patient’s chair is elevated to make this more comfortable, and the examiner is standing behind the patient. This allows full view of the cubical tunnel and surrounding muscles. The cubital tunnel may also be viewed in the described medial approach.

Anterior Elbow The anterior elbow includes structures from the pronator teres attachment on the medial epicondyle to the brachioradialis. From medial to lateral, the more superficial structures include the median nerve, brachial artery, brachialis muscle, biceps brachii muscle and tendon, and radial nerve (Fig. 8.1). These are best visualized with an axial view of the elbow (transverse or short axis to long bones) scanning 5 cm above and below the joint. The brachial artery is easily visualized just medial to the biceps brachii and noted with the pulsation and noncompressible nature (brachial vein is compressible). Just medial to the artery is the “honeycomb”-appearing median nerve. The biceps tendon can be followed to its insertion onto the radial tuberosity. Visualization of the bicep insertion is an important clinical point discussed later. Lateral to the biceps muscle, the radial nerve is found between the brachialis and brachioradialis. The nerve can be followed distally to where it divides into the superficial branch and the deep posterior interosseous nerve (PIN), which traverses the supinator muscles at the radial neck (Table 8.1). The deeper structures of the anterior elbow include the anterior recess, which appears as a concavity in the distal

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Fig. 8.1  Anterior structures of the elbow Ulnar nerve Biceps Brachial artery

Brachialis Median nerve

Radial nerve Posterior interosseous nerve

Medial epicondyle

Pronator teres (humeral head)

Supinator Brachioradialis Superficial branch radial nerve

Pronator teres (ulnar head)

Flexor carpi radialis

Flexor carpi ulnaris

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humerus. A fat pad normally resides in the fossa and may have a small amount of fluid behind the fat pad.

Medial Elbow The medial elbow includes the tendons of the medial epicondyle and the ulnar collateral ligament (UCL). The defining muscle is the pronator teres, which has two origins: one just proximal to the epicondyle and one on the ulnar aspect of the coronoid process. The median nerve traverses between these two origins of the pronator teres. Just medial to the pronator teres is the common flexor tendon inserting onto the medial epicondyle. This is comprised from lateral to medial of the flexor carpi radialis, palmaris longus, flexor digitorum superficialis, and flexor carpi ulnaris (see Figs. 8.1, 8.2, and 8.3). Deep to the common flexor tendon is the anterior band of the UCL. This is the major restraint to valgus stress. It arises from the anterior aspect of the epicondyle and inserts medial to the coronoid process on the sublime tubercle. This band is the only reliable band of the UCL that is well visualized by ultrasound. When imaging the medial structures, the longitudinal (long-axis) view over the epicondyle with the elbow in extension will demonstrate the UCL relatively hypoechoic to the common flexor tendon above (see Table  8.1). But if the elbow is in 90° of flexion with the abducted and externally rotated arm, the UCL will appear more hyperechoic.

Lateral Elbow Lateral elbow structures include the brachioradialis, extensor carpi radialis longus, the common extensor tendon, and the supinator muscles. The brachioradialis and extensor carpi radialis longus originate from the supracondylar ridge above the epicondyle separate from the common extensor tendon that originates on the anterolateral aspect of the lateral epicondyle (see Figs. 8.1, 8.3, and 8.4). The deepest of the lateral group is the superficial and deep portions of the supinator muscles. The superficial muscle originates from the posterior aspect of the epicondyle, annular ligament, and ulna fossa. The deep head originates from the supinator fossa of the ulna. Together, they wrap around the radial neck

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and insert on the proximal radial shaft to assist the biceps in supination. The superficial portion in some individuals forms a fibrous band called the “arcade of Frohse.” The PIN enters under the superficial head or, when present, the arcade of Frohse. The common extensor tendon is comprised of the extensor carpi radialis brevis (comprising most of the deep tendon), the extensor digitorum communis (comprising most of the superficial tendon), extensor digiti minimi, and extensor carpi ulnaris. These are best viewed in a longitudinal view (long axis) anterolaterally over the radial head (see Table 8.1). The underlying lateral collateral ligament is difficult to differentiate from the common extensor tendon.

Posterior Elbow The posterior elbow is comprised of the cubital tunnel medially, the triceps muscle, and the anconeus muscle laterally, which originates on the lateral olecranon and inserts on the posterior aspect of the lateral epicondyle. The triceps tendon represents the convergence of the medial, lateral, and long head of the triceps. This inserts distal to the tip of the olecranon. The olecranon bursa lies dorsal to the olecranon. The triceps tendon and olecranon bursa may be visualized in a longitudinal (long-axis) view. Proximal to the cubital tunnel, the ulnar nerve enters a fibro-osseous groove (cubital groove) between the olecranon and epicondyle. The roof is a fibrous covering called Osborn’s retinaculum or fascia and a floor formed by the posterior band of the UCL. In this space it is fairly mobile with flexion and extension. Distally, by about 1  cm, the nerve enters the true cubital tunnel between the two heads of the flexor carpi ulnaris, one from the olecranon and one from the medial epicondyle. The fibrous band between these two heads is an extension of Osborn’s fascia ligament proximally, and it is referred to as the arcuate ligament (Fig. 8.5). The ulnar nerve is best visualized in this groove with an axial view (transverse or short axis to nerve) and a small probe such as the hockey-stick probe (see Table  8.1). This allows for a dynamic exam of the ulnar nerve. As the elbow is slowly taken into full flexion, the medial triceps may cause subluxation of the nerve out of the groove.

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Table 8.1 Elbow Patient position Anterior elbow Patient seated with elbow extended on table. May use pillow for support

Transducer position and description

Transverse (or short-axis) view Scan from 5 cm above elbow to 5 cm below elbow. This is the “home row” and is a good reference point Anterior elbow

Longitudinal (or long-axis) view, Radial sagittal Scan across anterior elbow radial to ulnar aspect

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Image description and labeled structures

Pearls/pitfalls The radial nerve will split into the superficial branch and deeper branch Supination and pronation will demonstrate the annular ligaments of the radial head as well as insertion of the biceps tendon

Labeled structures: BT—biceps tendon BRA—brachialis muscle BR—brachioradialis muscle BA—brachial artery MN—median nerve HC/TROCH—humerus/trochlea PRO—pronator muscle

A small amount of fluid may be seen behind the fat pad of the radial and coronoid fossa and increased with elbow flexion

Labeled structures: RH—radial head HC—humeral capitellum SUP—supinator BR—brachialis

(continued)

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Table 8.1 (continued) Patient position Anterior elbow

Transducer position and description

Similar view, more medial, scan distally to see insertion of biceps tendon on the radius Anterior elbow

Similar view, more central

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Image description and labeled structures

Pearls/pitfalls The biceps tendon will demonstrate anisotropy artifact if the distal probe is not compressed as the tendon is followed more distally

Labeled structures: Radius BT—biceps tendon

Loose bodies sometimes can be identified with flexion. A small probe such as a “hockey-stick” probe may provide more detail Note that the brachialis has a short tendon compared to the biceps

Labeled structures: FP—fat pad BRACH—brachialis HUM—humerus COR—coronoid process CF—coronoid fossa

(continued)

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Table 8.1 (continued) Patient position Anterior elbow

Transducer position and description

Long-axis view Ulnar sagittal Medial elbow Patient seated holds arm abducted, supinated with 20° elbow flexion. Use pillow for support

Short-axis view

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Image description and labeled structures

Pearls/pitfalls The pronator teres has two insertions: one above the epicondyle and one at the coronoid tuberosity

Labeled structures: PRO—pronator teres muscle CFT—common flexor tendon ME—medial epicondyle

Use plenty of gel for this view, and/or consider using a hockey-stick probe

Labeled structures: CFT—common flexor tendon ME—medial epicondyle

(continued)

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Table 8.1 (continued) Patient position Medial elbow

Transducer position and description

Long-axis view Lateral elbow The patient is seated with elbow flexed, pronated, and adducted. May use pillow for support

Long-axis view

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Image description and labeled structures

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Pearls/pitfalls With 20° of flexion and valgus force, insufficiency of the UCL may be demonstrated but can be seen in asymptomatic throwers

Labeled structures: ME—medial epicondyle UCL—ulnar collateral ligament CFT—common flexor tendon UL—ulna

Labeled structures: LE—lateral epicondyle RH—radial head CET—common extensor tendon CL—collateral ligament

(continued)

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86 Table 8.1 (continued) Patient position Lateral elbow

Transducer position and description

Short-axis view Posterior elbow The patient is seated with the palm on the table and elbow flexion to 90°

Long-axis view

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Image description and labeled structures

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Pearls/pitfalls The radial nerve is seen on both anterior and lateral views. On the lateral view, the deep branch at the supinator muscles is viewed for any impingement. This is first identified on short axis, and the probe then turns long axis over the nerve, looking for a sudden decrease in diameter

Labeled structures: CET—common extensor tendon RN—radial nerve LE—lateral epicondyle

Olecranon bursa is not noted unless it is inflamed Apply light probe pressure over the olecranon bursa to avoid compressing a small fluid collection

Labeled structures: TT—triceps tendon OLE—olecranon FP—fat pad OR—olecranon recess

(continued)

H. M. Gillespie and P. d’Hemecourt

88 Table 8.1 (continued) Patient position Posterior elbow To make this easier on the patient, have patient supine, elbow propped up on towel, slightly flexed and externally rotated

Transducer position and description

Short-axis view

Oblique view, cubital tunnel

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Image description and labeled structures

Labeled structures: HUM—humerus Med—medial condyle Lat—lateral condyle Triceps—triceps tendon

Labeled structures: Triceps—triceps tendon OLE—olecranon

Labeled structures: UN—ulnar nerve ME—medial epicondyle OLE—olecranon FCU—flexor carpi ulnaris TT—triceps tendon

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Pearls/pitfalls Scan proximally to the myotendinous junction and distally to insertion of the triceps tendon on the olecranon The cubital tunnel can be seen from a medial or posterior view. Dynamic flexion of the cubital tunnel to assess for subluxation of the ulnar nerve is best done when seated with the medial view

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a

b

Medial view

Lateral view

Radial head

Radial head

Annular ligament

Medial epicondyle

Lateral epicondyle

Annular ligament

Biceps tendon Ulnar collateral ligament

Radial tubercle (insertion biceps tendon)

Olecranon

Olecranon Radial collateral ligament

Fig. 8.2  Medial ligaments of the elbow Fig. 8.3  Cross section of the elbow

Cephalic vein

Brachialis

Biceps

Brachial artery Median Nerve

Brachioradialis

Pronator teres

Extensor carpi radialis

Flexor carpi radialis Flexor digitorum

Radial head

Trochela

Radial annular ligament

Ulnar nerve Flexor carpi ulnaris

Ulna

Olecranon

Probe Selection

Specific Presets

A high-frequency probe is best for superficial structures like the elbow. A 5–15-MHz linear array transducer is used. A hockey-stick probe (5–10  MHz) may be useful around the medial and lateral elbow, especially for interventional ­procedures. This smaller probe will also allow easier dynamic flexion of the elbow.

A narrow field of view is best for these superficial structures. The focal zone should be set in a shallow range. The higher-­ frequency range of the probe is usually best for most elbow structures. However, for the deeper structures, such as the distal biceps, or when looking in the recess for loose bodies, a lower setting is used for better visualization. Finally, power

8 Elbow

91 Triceps brachii muscle Brachioradialis muscle

Cubital groove w/ulnar nerve Olecranon of ulna Anconeus muscle

Flexor carpi ulnaris muslce

Extensor carpi radialis longus muscle

Common extensor tendon

Extensor carpi ulnaris muslce

Fig. 8.4  Posterior structures of the elbow

Ulnar nerve

Medial epicondyle Osborne’s fascia Cubital tunnel Two heads of FCU

Fig. 8.5  Deep structures of the elbow demonstrating the route of the ulnar nerve and sites of possible entrapment

Doppler imaging may be used to look for inflammation as well as neovascularization in tendinopathy.

Common Problems Anterior Elbow Distal Biceps Distal bicep pathology, including tendinopathy and rupture, can cause anterior elbow pain. The ultrasound probe should

follow the tendon in a long-axis view to its insertion on the radial tuberosity with the elbow in full supination. This is a sagittal oblique plane. The probe should be kept parallel to the visualized tendon to avoid anisotropy artifact. This requires that the distal end of the probe be pushed gently into the soft tissue as the tendon turns deeper at the insertion. This will maintain a parallel configuration of the probe to the distal tendon. The probe may then be turned to an axial (transverse or short-axis) view of the tendon insertion, and possible bursa enlargement may be seen when the forearm is pronated. Ultrasound is unique compared to other imaging methods in this location because dynamic pronation and supination will demonstrate the bursa size change. The insertion site may also be viewed from a dorsal approach with the forearm pronated.

 osterior Interosseous Nerve Impingement P The deep branch of the radial nerve may be impinged at the edge of the superficial supinator muscle (arcade of Frohse), between the supinator muscles, by scar tissue or by a recurrent radial artery. This will often mimic lateral epicondylitis. It is best identified on an axial (transverse or short-axis) view above the elbow crease between the brachioradialis and brachialis (see Table  8.1). The axial (transverse or short-axis) view is followed down to the supinator muscles at the radial neck. The probe may then be turned to a longitudinal (long-­axis) view of the nerve by centering the nerve and then slowly turning the probe, maintaining the nerve as the central focus. An impinged nerve will often appear swollen and hypoechoic above the area of constriction.  nterior Recess Assessment A Longitudinal (long-axis) views of the anterior recess are helpful in assessing the amount of joint effusion. Normally, a small amount of fluid may exist under the hyperechoic fat pad. Pathologic increases in effusion may be demonstrated by passively flexing the elbow. The smaller hockey-stick probe may be useful in this setting. Small loose bodies sometimes are visible with this technique of flexion and compression of the joint posteriorly. Chip fractures off the coronoid process may also be seen.

Medial Elbow Medial Epicondylosis The common flexor tendon may be predisposed to tendon degeneration with repetitive elbow valgus force combined with eccentric stresses of pronation and flexion from sports such as pitching and golf. This may present with medial elbow pain that is aggravated by resisted flexion and pronation. The ultrasound imaging may demonstrate partial tears or hypoechoic intrasubstance changes of the common flexor tendon. Insertional enthesopathy may demonstrate bony irregu-

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larities of the epicondyle. The power Doppler is useful to demonstrate neovascularization consistent with tendinopathy.

 lnar Collateral Ligament Injury U Injury to the UCL may occur with an acute injury such as an elbow dislocation. More commonly, it is secondary to an overuse valgus stress, such as with a baseball pitcher. It may present quite similarly to medial epicondylosis and may have coexisting tendinosis of the common flexor tendon. The UCL may be fully or partially torn. When partially torn, the ligament will demonstrate thickening and hypoechoic changes. There can sometimes be some associated ligament calcification. When the ligament is fully torn, a frank breach in the ligament may appear. Alternately, it may be manifested by soft-­ tissue indentation of the ligament. Widening of the joint or gapping of the UCL may be demonstrated with valgus stress.

Lateral Elbow Lateral Epicondylosis The common extensor tendon may be injured due to partial- or full-thickness tears. More commonly, it is involved in tendinosis with tendon degeneration and intrasubstance tearing. This is classically known as “tennis elbow” due the eccentric overload of the backhand. However, it is more commonly seen as a tendinosis of the nonathletic population and presents with lateral elbow pain worsened with wrist extension. Ultrasound imaging of the common extensor tendon most commonly demonstrates hypoechoic changes in the tendon distal to the insertion. The deeper extensor carpi radialis brevis tendon is the most common area involved. However, insertional enthesopathy may also be demonstrated with bony irregularities on the epicondyle. There is commonly some peritendinous fluid noted. Power Doppler is often useful in demonstrating marked neovascularization most commonly in the extensor carpi radialis brevis.

Posterior Elbow  istal Triceps Tendon Injury D Acute rupture of the triceps tendon manifests with inability to extend the elbow. When there is a lot of swelling and pain inhibiting the exam, the ultrasound is valuable in demonstrating tendon disruption with wavy appearance of the distal tendon and retraction. Chronic tendinosis may also occur and is manifested with hypoechoic areas in the tendon along with neovascularization seen on power Doppler. One must be careful to not overinterpret the fat that normally sits between the layers of triceps as tendinosis. Cubital Tunnel Syndrome Excessive compression of the ulnar nerve may occur within the proximal cubital groove or the more distal cubital tunnel. This may be secondary to extrinsic compression of the nerve

H. M. Gillespie and P. d’Hemecourt

by thickened arcuate ligament, bony spurs, and soft-tissue masses such as a lipoma. Inflammatory and crystal diseases are also considered. These patients will present with medial elbow pain and signs of distal nerve compression with paresthesias of the ulnar two fingers and intrinsic muscle wasting. The most common sonographic finding is sudden narrowing of the nerve at the compression site with proximal swelling of the nerve. A cross-sectional area of greater than 7.9  mm2 has been identified as an upper limit of normal for the ulnar nerve. Inflammation around the nerve may also be seen.

Cubital Instability The ulnar nerve may sublux out of the cubital groove or frankly dislocate in elbow flexion. This is usually caused by the medial portion of the triceps muscle and can easily be seen with an axial (transverse or short-axis) view of the cubital groove with flexion of the elbow. However, this may be seen in asymptomatic individuals. Olecranon Bursitis The olecranon bursa is dorsal to the olecranon and quite superficial. It is not usually visible unless inflamed or infected. It will readily appear as a hypoechoic fluid collection when enlarged. A thickened wall may appear if chronically inflamed. Local trauma and inflammatory and infectious causes must be considered. Calcific triceps tendinopathy may also cause bursa swelling.

Red Flags • When a ruptured distal biceps is suspected, the ultrasound is not the definitive imaging method. The angular changes of the distal biceps make it difficult to differentiate ­anisotropic changes from tendon tears. Furthermore, there are two heads of the biceps insertion, the long and short heads. The long head may not be visible at its deeper attachment to the radial tuberosity. • When a joint effusion is noted, it is not possible to distinguish an infected from an inflamed effusion. Aspiration may be indicated to make this differentiation. • Avoiding injection into vessels is critical. Particularly when injecting near the deep branch of the radial nerve and the ulnar nerve, use of power Doppler is helpful in identifying the recurrent radial and ulnar arteries.

Pearls and Pitfalls • The elbow has many bony prominences that provide sudden changes in tendon direction. As such, the ultrasound beam will suddenly lose its perpendicular alignment with

8 Elbow

•

•

•

•

•

the tendon, and artifact anisotropy is common. This is particularly true of the biceps tendon. It is important to toggle the probe in a heel-to-toe manner with compression gently into the soft tissues distally. This will allow reduction of the anisotropy. On the medial aspect, a common injection is the peritendinous area of the common flexor group. Here, the supine patient places the arm in abduction and external rotation with full supination. Varying amounts of elbow flexion are used depending on the patient. A longitudinal (long-­ axis) view of the tendon is attained on the medial aspect of the medial epicondyle, which is kept in view. The ulnar nerve and median nerve with brachial artery should have been previously identified and avoided. The approach is from distal to proximal with an in-plane approach. Care is taken to avoid entering the tendon as well as being too superficial if corticosteroids are injected, because they can cause fat atrophy and depigmentation. When approaching a peritendinous injection of the common extensor tendon, the supine patient places the elbow in about 40° of flexion with full pronation of the forearm. The image is attained in the longitudinal plane (long axis) just to the volar side of the common extensor tendon over the radial head. An in-plane approach from distal to proximal is performed. The radial nerve and recurrent radial artery should be avoided. Avoid entering the tendon or being too superficial as above. The cubital tunnel provides a very narrow area for the probe in a transverse or short-axis view. This will narrow the field of view significantly. To enhance this step, standoff gel pads may be used for visualization and are available in sterile disposable forms for interventional procedures. Alternatively, copious amounts of gel under the edges will fill the gap for peripheral visualization. Dynamic maneuvers may offer tremendous advantages to the elbow examination, but abnormalities do not always indicate pathology. For instance, valgus stress of the elbow imaged medially in about 20° of flexion is a nice technique to demonstrate laxity of the UCL.  However, asymptomatic pitchers have demonstrated increased laxity of the medial joint that does not need intervention. This is likely due to chronic stretch to the ligament. Similarly, subluxation of the ulnar nerve over the epicondyle may be demonstrated with an axial (transverse or short-axis) view of the cubital tunnel during flexion. Here, the distal triceps may sublux the nerve over the epicondyle or even dislocate over the common flexor tendon. This has been demonstrated in over 15% of the normal asymptomatic population. However, in unusual cases it may be associated with friction neuritis and demonstrated

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with focal swelling of the nerve at the area of subluxation. This is best demonstrated on a long-axis view of the nerve.

Clinical Exercise Certain “homework assignments” are easily achieved for the elbow. The student can readily examine his or her own nondominant elbow. In the seated position and facing the ultrasound monitor, the following steps are performed and recorded: 1. The imaging settings are set for the linear array probe for a high frequency (10–17 MHz). The depth is set to a shallow level with a shallow focus. 2. The anterior elbow is visualized in an axial (transverse or short-axis) plane above, at, and below the joint. An image is recorded with identification of the pronator teres, median nerve, brachial artery, brachialis muscle, biceps tendon with muscle, and radial nerve. The probe is then turned longitudinally (long-axis view), and images are taken in the radial and ulnar sagittal views. The technique of changing from a transverse or short-axis to a longitudinal or long-axis view while maintaining a central view of the biceps tendon is practiced. The brachialis and biceps tendons are identified along with the anterior recess. Heel-to-toe toggle on the biceps tendon distally is used to demonstrate anisotropy. 3. The medial elbow is imaged in the longitudinal (long) axis over the UCL and common flexor tendon. The image is recorded with identifying markings of these two structures. 4. The lateral elbow is imaged over the lateral epicondyle in a longitudinal (long-axis) view of the common extensor tendon over the lateral epicondyle and radial head. These structures are imaged with identifying markers.

Suggested Reading AMSSM Sports Ultrasound Online Didactics. https://www.amssm.org/ UltrasoundOnlineDidactics.php. Beggs I, Bianchi S, Buenos A, Cohen M, Court-Payen FM, Grainger A, et al. Musculoskeletal ultrasound technical guidelines II. Elbow. Eur Soc Musculoskelet Radiol. https://essr.org/content-­essr/ uploads/2016/10/elbow.pdf. Bianchi S, Martinoli C.  Elbow. In: Bianchi S, Martinoli C, editors. Ultrasound of the musculoskeletal system. Berlin: Springer; 2007. p. 349–407.

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Shoulder Mark E. Lavallee

Approach to the Joint

Probe/Machine Settings

The shoulder is comprised of three bones: the humerus, the clavicle, and the scapula. The shoulder contains four joints: the glenohumeral joint, the acromioclavicular joint, the sternoclavicular joint, and the scapulothoracic joint. The first three joints can be easily visualized by ultrasound. Anterior structures include the long head of the biceps tendon, the subscapularis muscle/tendon, the anterior deltoid, the acromioclavicular capsule, and the coracoid process. The superior structures include the acromioclavicular joint/ capsule, the clavicle, the acromion process, and the trapezius. The lateral structures include the deltoid, the subscapularis, the supraspinatus, the subacromial bursa, the joint capsule, and the superior labrum. The posterior aspects of the shoulder include the scapula, the trapezius, the supraspinatus, the infraspinatus/teres minor, the subscapularis, the joint capsule, the suprascapular nerve, the posterior labrum, and the rhomboid muscles. With ultrasound, you can look at these structures both statically and with dynamic motion.

For the shoulder examination, using the linear array probe is recommended. High-frequency linear probes can range from 5 to 15 MHz with frequencies between 7 and 10 MHz best for imaging the rotator cuff, with the focal position usual being between 2 and 4 cm. The shoulder joint requires a specific number of images be captured to be considered a complete scan. Anything less than this number will be considered a limited scan by most insurance carriers. A complete scan of the shoulder [1] contains the following captured views:

M. E. Lavallee (*) York Sports Medicine Fellowship Program, York, PA, USA Department of Family Medicine, Pennsylvania State University, School of Medicine, Hershey, PA, USA Department of Family, Drexel University, Philadelphia, PA, USA

• Long head of biceps tendon (anterior) in bicipital groove (transverse or short and longitudinal or long axis) • Subscapularis tendon (anterior) external rotation (short and long axis) • Supraspinatus, biceps tendon, and subscapularis tendon (rotator cuff interval) (anterolateral) • Supraspinatus tendon (anterolateral) (short axis) • Infraspinatus/teres minor (posterior) (long axis) • Subacromial bursa (if present) • Acromioclavicular joint (coronal) • Glenohumeral joint (posterior) (short axis) • Spinoglenoid notch • Suprascapular notch (optional) Additional imaging that may be done if needed or desired may include: • Dynamic views of the rotator cuff • Contralateral shoulder as needed to assess normal

Gettysburg College, Gettysburg, PA, USA International Weightlifting Federation, Medical Committee, Budapest, HUN, Hungary

Common Conditions

USA Weightlifting, Sports Medicine Society, Colorado Springs, CO, USA

The following sections discuss the most common pathologic conditions that lend themselves to visualization using ultrasound.

Thomas Hart Family Practice Center, York, PA, USA e-mail: [email protected]

© Springer Nature Switzerland AG 2021 J. M. Daniels, W. W. Dexter (eds.), Basics of Musculoskeletal Ultrasound, https://doi.org/10.1007/978-3-030-73906-5_9

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Partial-Thickness Rotator Cuff Tear

Calcific Tendonitis

With ultrasound, the examiner should be able to ascertain if the tear is humeral side/inferior side/“chondral side” or acromial side/superior side/“bursal” side. It is important to view the supraspinatus’s “critical area,” near the insertion on the greater tuberosity of the humerus (Fig. 9.1).

Ultrasound is able to pick up small calcific areas in the supraspinatus tendon, especially when assessed dynamically. MRI and CT scan can visualize this pathology, if larger than 5 mm. Most symptomatic lesions are 5 mm or less. Plain radiographs also identify these calcifications (Fig. 9.3a, b).

Complete-Thickness Rotator Cuff Tear Static ultrasound may show retraction of supraspinatus tendon. A dynamic evaluation may show this when it is not evident on static examination (Fig. 9.2).

Fig. 9.1  Partial undersurface tear of supraspinatus (marked with asterisk)

a Fig. 9.3 (a, b) Calcification in infraspinatus

Fig. 9.2  Complete tear with retraction of supraspinatus

b

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Fig. 9.5  Acromioclavicular joint with arthropathy

Fig. 9.4  Increased fluid around biceps tendon (BT), long-axis view

Biceps Tendonitis/Tenosynovitis Ultrasound is able to ascertain between normal tendon vs. diseased tendon (partial/full tears, tendonosis). Short-axis view of proximal biceps tendon will show a hyperechoic “fluid ring” around the tendon if there is fluid in the sheath. Ultrasound is effective at seeing neovascularization, a pathologic condition associated with tendonosis, which MRI, CT, and radiographs were not able to assess (Fig. 9.4).

Fig. 9.6  Subacromial-subdeltoid bursitis (SASD)

Acromioclavicular Joint Arthropathy

Adhesive Capsulitis

Radiographs are the mainstay for grading acromioclavicular separations and degenerative joint disease. Ultrasound also identifies osteophytes and narrowed joint space; however, it also allows visualization of the “geyser” appearance of a joint effusion and thickened capsule (Fig. 9.5).

A thickened glenohumeral capsule can be seen on anterior and posterior views. Capsular distension via intra-articular injection under ultrasound guidance is often easily accomplished and visualized.

Subacromial Bursitis Ultrasound is highly sensitive tool to see this structure. It can often be missed on MRI, if sequencing or image cuts are greater than 2 mm (Fig. 9.6).

Biceps Tendon Subluxation This is rarely diagnosed in static imaging studies like MR or CT, but ultrasound can easily see this dynamically.

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Red Flags

Probe Choice

There are some conditions that need urgent attention. These include posterior dislocation of the sternoclavicular joint, as it may compress the internal/external carotids. This is a vascular emergency on many different levels. Vascular ultrasound is beyond the scope of this chapter, but in an emergency situation, the vessels can be imaged quickly via the color flow or Doppler flow setting on the machine. Other emergencies in relation to the shoulder, like glenohumeral dislocation or humeral neck fracture, lend themselves to radiography as the preferred imaging choice. Although sonographic imaging is not preferred, it could be utilized in a situation where radiography and other modalities are not accessible. Subclavian steal syndrome, brachial artery thrombosis, aneurysm, and dissection are all urgent conditions in the shoulder region that are best imaged via vascular ultrasound, MR, or CT angiography. Do not try to use ultrasound to rule out labral pathology. Though certain aspects of the labrum can be visualized and even labral tears diagnosed, ultrasound does not truly inspect the whole labrum. MRI or MR arthrogram is currently the most sensitive diagnostic imaging for labral tear. It should be mentioned that although ultrasound is excellent at identifying fluid-filled superficial structures (i.e., bursas, hematomas, and joint capsules), the current technology is starting to between different types of fluids. A hemarthrosis and a septic joint will look similar, and one cannot determine whether an enlarged subacromial bursa is infected or just inflamed.

For most patients, a linear probe with 3 to 15 MHz will suffice. The examiner might find it useful, especially with larger patients, to switch to a curvilinear probe particularly for the posterior shoulder examination.

Pearls and Pitfalls Here are some common tips that might prove helpful:

Anisotropy When looking at the insertion point of a rotator cuff muscle, realize the hypoechoic area at the insertion may not be a tear but anisotropy (echo shadow). This can be delineated by slow activation of the glenohumeral joint or “toggling” the transducer, which will remove the anisotropy.

Positioning Getting your patient (and yourself) into a stable and relaxed position is crucial. The patient can be seated on a stool rather than the exam table which allows the examiner to move the patient easily. The examiner may stand or also be seated on a stool (slightly higher than the patient). Many learners tend to grip the probe too high and too tight or insist on standing (instead of sitting). Sit down and relax your grip. Position your hand at the distal part of the probe. Allow part of your hand or fingers to rest on the patient for stability.

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Orientation Every time you place your probe on the patient’s skin, orient yourself! Place only one corner of the linear probe on the patient’s skin in order to confirm which side of visual field is medial vs. lateral or proximal vs. distal.

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ited scan, 3–6 images. Minimize video clips (make them short, as they can easily take up your memory).

Become Ambidextrous Learn to hold the probe and scan with either hand. Also, become comfortable with injecting with either hand.

Color Flow For musculoskeletal conditions, color flow is usually not needed unless looking at vasculature or injecting under ultrasound. Color flow can also be used to ascertain if a structure has neovascularization, a pathologic condition, waders.

Depth Adjust the depth of visual field to the lowest allowable in order to see the structures you need to see. This allows a wider viewing area and more resolution.

Pictographs Consider using these if available. Pull them in prior to scanning. They will save you lots of editing and typing later.

Save Images After capturing still or video clips of structures, do not forget to label and save the image. For a complete shoulder exam, you should have saved around 10–12 images and, for a lim-

Advanced Use of Ultrasound Certain conditions may render themselves to imaging via ultrasound once a clinician is more experienced; these conditions include distal biceps tendon injury, nerve evaluation, SLAP tears, and anterior glenohumeral labrum.

Clinical Exercises 1. Attempt to find these structures when doing the ultrasound exam of the shoulder. In order to perform a “complete” shoulder exam, one will need to be able to capture all of these images: • Biceps tendon (anterior view) • Subscapularis (anterior approach) • Dynamic examination for biceps tendon subluxation (as indicated) • Acromioclavicular joint (anterior and superior views) • Infraspinatus (posterior approach) • Posterior glenohumeral joint (posterior view) • Coracoid process and anterior humeral head (anterior view) approach for anterior intra-articular glenohumeral injection

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Fig. 9.7  Anterior shoulder anatomy

Acromion clavicular joint Clavicle

Acromion Coracoid process Supraspinatous

Pectoralis minor tendon

Subscapularis

Bicipital groove Pectoralis major tendon Biceps – long head Humerus

Glenohumeral joint

Biceps – short head Teres major Latissimus dorsi

• Supraspinatus (short and long axis) and subacromial bursa • Dynamic rotator cuff evaluation • Spinoglenoid notch (posterior view) • Rotator cuff interval: supraspinatus, biceps tendon, and subscapularis (“Marilyn Monroe” shot or “hand in back pocket” shot) 2 . Anterior shoulder.

For anatomical structures, see Figs. 9.7 and 9.8. • Identify biceps tendon and bicipital groove of humerus. • Attempt a dynamic examination of the proximal biceps tendon to attempt to sublux it. Capture video clip while flexing elbow with resisted external rotation at shoulder.

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• Identify subscapularis (arm externally rotated). Identify the supraspinatus, biceps tendon, and subscapularis, all in one image. Rotator cuff interval or “Marilyn Monroe” shot. • Identify coracoid process and humeral head in same image (anterior injection portal). • Dynamic view of the anterior shoulder during internal and external rotation. Note: appearance of ­subscapularis with external rotation and then appearance of supraspinatus with internal rotation. 3 . Lateral shoulder. • Identify supraspinatus as it inserts on the humeral head (short- and long-axis views) (posterolateral portal for subacromial injection). • Identify subacromial bursa. Measure with calipers its length, height, and circumference. • Dynamically visualize supraspinatus when shoulder is abducted. Look for impingement. 4. Posterior shoulder. • Identify infraspinatus, as it inserts onto humeral head. • Identify posterior glenohumeral joint capsule and labrum (posterior portal for subacromial injection). • Identify the spinoglenoid notch, deep to infraspinatus. For anatomical structures, see Figs.  9.8 and 9.9; Tables 9.1, 9.2, and 9.3.

a

Transverse or axial Biceps (in bicipital head Biceps short head Glenoid

Deltoid Humeral head

Subscapularis Scapula Infraspinatous

b

Sagittal Clavicle Corocoid Biceps long head

AC joint Acromion process Supraspinatous Glenoid fossa

Subscapularis Infraspinatous Teres minor

Fig. 9.8  Cross-sectional anatomy

Fig. 9.9  Posterior shoulder anatomy Clavicle AC joint Scapular spine Deltoid Infraspinatous Teres major Latissimus Humerus

Supraspinatous Acromion Glenohumeral joint Greater tuberosity Teres minor

Triceps

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Table 9.1  Anterior shoulder Patient position Patient is seated, arm at side, elbow flexed, palm up

Transducer position and description

Transverse or short-axis view Probe over anterior deltoid, short axis to upper arm Patient is seated, arm at side with elbow flexed, palm up, and the arm is externally rotated

Short-axis view Probe over anterior deltoid, short axis to upper arm

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Picture of scan and labeled structures

Pearls/pitfalls Look for fluid around tendon as a sign of tenosynovitis. Fluid and/or defects in the tendon indicate a tear. Assess muscle tendon junction by scanning distally

Short-axis image Labeled structures BT—biceps tendon GT—greater tuberosity LT—lesser tuberosity SUSC—subscapularis

Dynamic biceps evaluation To assess for subluxation of biceps tendon, have patient seated, arm at side, elbow flexed. Externally rotate forearm with elbow at side, palm up. Look for the biceps tendon moving out of bicipital groove

Dynamic scan Labeled structures BT—biceps tendon BG—bicipital groove

(continued)

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Table 9.1 (continued) Patient position Patient is seated, arm at side, elbow flexed, palm up

Transducer position and description

Longitudinal or long-axis view. Probe over anterior deltoid, longitudinal to upper arm Patient is seated, arm at side, elbow flexed, palm up, may externally rotate to improve view. Slide probe medially from biceps

Short-axis view Probe over anterior deltoid, axial

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9 Shoulder

Picture of scan and labeled structures

Pearls/pitfalls Scan biceps distally to the muscle tendon junction

Long-axis image Labeled structures BT—biceps tendon HUM—humerus

The darker areas interspersed between the whiter-­appearing tendon fibers are muscle tissue. This is differentiated from anisotropy or injury

Short-axis image Labeled structures HUM—humerus SUSC—subscapularis

(continued)

M. E. Lavallee

106 Table 9.1 (continued) Patient position

Transducer position and description

Long-axis view Longitudinal to upper arm Patient facing direction of shoulder being studied, 90° to the examiner with hand on “back pocket” and elbow tucked in (modified Crass technique)

Long-axis view: supraspinatus Relocate bicipital groove and identify footprint of supraspinatus

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Picture of scan and labeled structures

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Pearls/pitfalls Given the orientation of the subscapularis, the probe is actually in a somewhat transverse or oblique orientation

Long-axis image Labeled structures HUM—humerus SUSC—subscapularis

Supraspinatus LA, or “bird beak” view. If fluid is present in the subacromial-subdeltoid bursa, it will be seen as a dark strip between the deltoid and the supraspinatus Signs of damage include a “dented” appearance to the SS tendon, hypoechoic areas (beware anisotropy!), bright or hyperechoic signal of the articular cartilage. Make sure to carefully evaluate the “critical zone” of the SS (at the insertion on the humerus)

Long-axis image Labeled structures DEL—deltoid SS—supraspinatus HUM—humerus (continued)

M. E. Lavallee

108 Table 9.1 (continued) Patient position Similar position as for LA view of supraspinatus

Transducer position and description

Short-axis view Probe angled obliquely

Patient is seated, arm at side, elbow flexed, palm up

Short-axis view Probe over anterior deltoid and coracoid process, axial to upper arm

9 Shoulder

Picture of scan and labeled structures

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Pearls/pitfalls This position shows the “rotator cuff interval”; proximal biceps tendon is seen between the supraspinatus and the subscapularis tendons

Labeled structures DEL—deltoid muscle BT—biceps tendon SS—supraspinatus SUSC—subscapularis HUM—humerus Preferred approach for anterior glenohumeral injection Can often visualize a portion of superior labrum. Tip: palpate coracoid to find place to anchor medial aspect of probe

Long-axis image Labeled structures COR—coracoid process GHJ—glenohumeral joint HH—humeral head (continued)

M. E. Lavallee

110 Table 9.1 (continued) Patient position Same position

Transducer position and description

Oblique view, slide lateral aspect of probe superior toward the acromion

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Picture of scan and labeled structures

Long-axis image Labeled structures COR—coracoid process C-AL—coracoacromial ligament ACR—acromion

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Pearls/pitfalls In order to visualize the coracoacromial ligament, anchor the probe medially on the coracoid, and slide the lateral aspect of the probe superiorly to the acromion

M. E. Lavallee

112 Table 9.2  Superior and lateral shoulder Patient position Patient is seated, arm at side, elbow flexed, palm up

Transducer position and description

Long axis over distal clavicle

Similar position to above, slide probe slightly laterally over acromion Abduct internally rotated shoulder

Probe long axis to clavicle, over lateral acromion and deltoid

Dynamic, long axis

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Picture of scan and labeled structures

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Pearls/pitfalls Sweep probe from anterior to posterior. Thickened capsule, narrowed joint space, osteophytes indicate a degenerative joint. Look for increased fluid or a “geyser” sign (fluid expressed from joint with active compression). Could indicate trauma, arthritis

Labeled structures ACJ—acromioclavicular joint JC—joint capsule ACR—acromion CL—clavicle Top screenshot is with arm by patient’s side Bottom picture is with arm abducted. If impingement is present, the supraspinatus will “bunch up” under the acromion. Note small dark line that is fluid in a subacromial subdeltoid bursa

ACR—acromion process SS—supraspinatus DEL—deltoid HUM—humerus

ACR—acromion process DEL—deltoid SASB—subacromial subdeltoid bursa HUM—humerus

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Table 9.3  Posterior shoulder Patient position Transducer position and description Patient is seated, back to examiner, arm at side, elbow flexed, internally rotate shoulder—palm on abdomen

Short axis to humerus As above

Short axis to humerus As above

Slide probe slightly distally to visualize teres minor

9 Shoulder

Picture of scan and labeled structures

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Pearls/pitfalls Scanning superior to the scapular spine visualizes the supraspinatus muscle. Below the spine, the infraspinatus is seen and inferior to this the teres minor This is a preferred posterior approach for glenohumeral joint injections

Labeled structures: Hum—humerus L—labrum GL—glenoid IS—infraspinatus

Slide probe slightly medially to visualize spinoglenoid notch Adjusting the focal zone, the suprascapular artery and nerve that run in the spinoglenoid notch can be seen

Labeled structures: HUM—humerus LAB—labrum GLEN—glenoid SNG—spinoglenoid notch IS—infraspinatus

The teres minor can be difficult to find as the fibers can blend into the infraspinatus. Look for a hyperechoic fascial plane that can help delineate these muscles/tendons

Labeled structures: HUM—humerus TM—teres minor

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Reference 1. American Institute of Ultrasound in Medicine. AIUM practice guideline for the performance of a shoulder ultrasound examination. J Ultrasound Med. 2003;22(10):1137–41.

Suggested Reading Beggs I, Bianchi S, Bueno A, Cohen M, Court-Payen M, Grainger A, et al. Musculoskeletal ultrasound technical guidelines. I. The shoul-

M. E. Lavallee der. Eur Soc Musculoskelet Radiol. http://www.essr.org/html/img/ pool/shoulder.pdf Hill J, Lavallee M. Musculoskeletal ultrasonography. In: Pfenniger JL, Fowler GS, editors. Pfenniger and Fowler’s procedures in primary care. 3rd ed. New York: Elsevier; 2011. p. 1233–45. McNally E. Practical musculoskeletal ultrasound. New York: Churchill Livingstone; 2005.

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Foot and Toes Kate Quinn

Approach to the Joint In order to image the foot and toes, the examiner should sit at the end of the examination table where the limb is extended or positioned facing the examiner. The ultrasound should be placed adjacent to either the side of the table facing the examiner for ease of viewing. The patient may need to be positioned supine, prone, or in the lateral decubitus position in order to visualize the various structure being imaged. Generally, the area being imaged should be placed upward or toward the examiner (Table  10.1). Figures  10.1 and 10.2 demonstrate the basic anatomical relationships in the foot.

Probe/Machine Setting and Technique A linear transducer with medium to high frequency of 12 MHz is recommended. Preferably a higher frequency is used for imaging of toes. A “hockey stick” probe allows for easier visualization of smaller joints and structures. A “standoff” may be used to accommodate the bony contours of the toes. Machine settings of a shallow depth of 2–3  cm and as high a frequency probe setting as possible are recommended.

Common Pathologic Conditions The most common pathologies evaluated and treated of the foot and toes by ultrasound include plantar fasciitis, sinus tarsi syndrome, interdigital neuromas, and various arthritis

conditions. Other conditions include nerve entrapments including medial and lateral plantar nerves, medial calcaneal nerve, fractures of the metatarsals or digits, and midfoot (Lisfranc) sprains.

Red Flags Approaching the subtalar joint from a posteromedial approach is not advisable due to close proximity and potential injury of the posterior tibial artery, veins, and tibial nerve. Differentiate an interdigital neuroma which has a fusiform shape continuous with the interdigital nerve from an interdigital bursa which lies more dorsally in the interdigital interspace.

Pearls and Pitfalls A subtalar joint injection can be approached from either the anterolateral or posterolateral direction. This joint is located cranially to the peroneal tendons. The anterolateral approach involves the short-axis orientation and the shortest needle path. The posterolateral method involves a steeper angle and longitudinal axis orientation. The ultrasound cannot distinguish between infection and inflammatory arthritis when evaluating a subtalar or digital joint effusion. Perform weight-bearing imaging including X-rays of bilateral feet when you suspect a midfoot sprain to determine if there is any widening or step-offs of any tarsometatarsal joints.

K. Quinn (*) Maine Medical Partners Orthopedics and Sports Medicine, Division of Sports Medicine, South Portland, ME, USA e-mail: [email protected] © Springer Nature Switzerland AG 2021 J. M. Daniels, W. W. Dexter (eds.), Basics of Musculoskeletal Ultrasound, https://doi.org/10.1007/978-3-030-73906-5_10

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118 Table 10.1  Foot and toes Patient position Patient supine, knee bent with plantar aspect foot flat on the table or standing

Transducer position and description

Longitudinal (or long) axis to foot: °Midfoot at TMT As above

Short axis to foot: -Midfoot at proximal inter-­metatarsal spaces

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Picture of scan and labeled structures

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Pitfalls/pearls Good position to evaluate for midfoot sprains and midfoot or metatarsal fractures. Can do weight-bearing images to look for widening between bones

Labeled structures: MID CUN – middle cuneiform MT – metatarsal

As above

Labeled structures: MT – metatarsal (1st, 2nd, 3rd)

(continued)

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Table 10.1 (continued) Patient position As above. Or patient lying lateral recumbent on affected side, lateral aspect of affected foot contacting table, medial aspect foot facing ceiling

Transducer position and description

Long axis to 1st MTP (metatarsophalangeal) joint, medially or dorsally Patient lying lateral recumbent on affected side, lateral aspect of affected foot contacting table, medial aspect foot facing ceiling or in prone position

Long axis to 1st MTP joint, plantar

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Picture of scan and labeled structures

Pitfalls/pearls Good position for out of plane injection to first MTP. Gentle traction can aid in opening the MTP joint. Access the joint space medial to the EHL (extensor hallucis longus) tendon with needle short axis to transducer

Labeled structures: PROX PHAL – proximal phalanx 1ST MT – first metatarsal 1ST MTP – first metatarsophalangeal joint

Labeled structures: FHLT – flexor hallucis longus tendon MT – metatarsal MTP – metatarsophalangeal joint PP – proximal phalanx

(continued)

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Table 10.1 (continued) Patient position Transducer position and description Patient lying lateral recumbent on affected side, lateral aspect of affected foot contacting table, medial aspect foot facing ceiling or in prone position

Sesamoids: -Short axis to 1st MTP joint plantar surface Patient lying lateral recumbent on affected side, lateral aspect of affected foot contacting table, medial aspect foot facing ceiling or in prone position; apply pressure with finger to dorsal interdigital area

Interdigital neuroma: -Short axis over affected interdigital space

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Picture of scan and labeled structures

Pitfalls/pearls Position to evaluate for sesamoid fracture or subluxation

Labeled structures: FHLT – flexor hallucis longus tendon MED/LAT SES – medial and lateral sesamoids 1st MTH – first metatarsal head

Compress tissue between finger on dorsal aspect and probe on plantar aspect to reproduce symptoms and confirm location of neuroma

Labeled structures: METATARSAL HEADS 4TH, 3RD, 2ND

(continued)

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Table 10.1 (continued) Patient position Transducer position and description Patient lying lateral recumbent on affected side, lateral aspect of affected foot contacting table, medial aspect foot facing ceiling or in prone position; apply pressure with finger to dorsal interdigital area

Long axis over affected interdigital space for neuroma Patient prone, foot hanging off edge of table, ankle in neutral position (Alternate: foot on table with rolled towel under ankle keeping ankle joint near neutral position)

Long axis to foot: -Plantar fascia, long axis

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Picture of scan and labeled structures

Pitfalls/pearls Fairly unremarkable looking when normal. Neuroma may appear as a fusiform hypoechoic thickening of the nerve

Labeled structures: FT – flexor tendon INTERDIGITAL SPACE Position ankle in neutral position to keep plantar fascia in taught position Fascia thicker than 4 mm with hypoechoic changes typically indicates plantar fasciitis [1] To inject the fascia, can approach in plane or out of plane with transducer. When injecting out of plane, approach from medial direction

Labeled structures: Plantar Fascia FDB – flexor digitorum brevis Calc – calcaneus Fat pad

(continued)

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Table 10.1 (continued) Patient position As above

Transducer position and description

Short axis to foot: -Plantar fascia, transverse Patient prone with hip and knee slightly flexed, hip externally rotated with medial aspect foot contacting table and lateral side facing ceiling

Sinus tarsi: transducer transverse or slightly oblique to long axis of the foot just anterior to the lateral malleolus

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Picture of scan and labeled structures

Pitfalls/pearls Image the proximal 1–2 cm of the fascia in the short-axis view where most plantar fasciopathy occurs Can inject in this position in plane with transducer from medial direction

Labeled structures: CALC – calcaneus PF – plantar fascia Talar neck and anterior process of the calcaneus form the sides of the deep, U-shaped sinus tarsi Injections can be done with this view using a short-axis approach with a needle angled steeply downward in anterior to posterior direction to reach the deep subtalar ligaments that usually cause pain here [2]

CALC – calcaneus TALUS SINUS TARSI

(continued)

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Table 10.1 (continued) Patient position Patient prone with hip and knee slightly flexed, hip externally rotated with medial aspect foot contacting table and lateral side facing ceiling

Transducer position and description

Subtalar joint, anterolateral: -Slide transducer from above location slightly posterior (toward heel) and distal (toward sole) Alternate subtalar joint approach: patient prone or kneeling, leg straight, foot hanging off end of table

Subtalar joint, posterolateral: -Lateral to Achilles tendon, rotate probe slightly medially and caudally

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Picture of scan and labeled structures

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Pitfalls/pearls Subtalar (talocalcaneal) joint is narrow and is located just cranially to the peroneal tendons, which are seen in cross section. If aspirating or injecting from this location using short-axis technique, take care to avoid the peroneal tendons and sural nerve, which are usually located caudal to the subtalar joint [3]

Labeled structures: CALC – calcaneus PT – peroneal tendons STJ – subtalar joint TALUS

Dorsiflex the ankle to better visualize the subtalar joint space. Using a thick gel layer and light pressure may be necessary to accommodate the patient’s contours; a hockey stick probe may also be helpful. A long-axis or in-plane approach can be used here to access the joint for injections or aspirations

Labeled structures: As above

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Fig. 10.1  Medial foot Extensor hallucis longus tendon Tibialis anterior tendon

Tibia Navicular

Tibialis posterior tendon

Cuneiform Metatarsal

Phalanx

Achilles tendon Flexor digitorum longus tendon

Extensor hallucis longus

Flexor hallucis longus Calcaneus (Calc) Talus

Sesamoid

Metatarsal phalangeal joint

Flexor hallucis longus tendon

Metatarsal head

Plantar fascia

Fat pad

Fig. 10.2  Lateral foot Fibula Extensor hallucis longus Extensor digitorum longus Sinus tarsi Talus Cuneiform

Achilles tendon Sub talar joint

Metatarsal phalangeal joint

Calcaneus Peroneus longus tendon Plantar fascia Peroneus brevis tendon

References 1. Beard N, Gousse R. Current Ultrasound Application in the Foot and Ankle. Orthop Clin N Am. 2018;49:109–21. 2. Smith J, Maida E, Murthy N, Kissin E, Jacobson J.  Sonographically Guided Posterior Subtalar Joint Injections

Long Metatarsal Metatarsal Phalanx plantar head ligament

via the Sinus Tarsi Approach. Journal of Ultrasound in Medicine. 2015;34(1):83–93. 3. Soneji N, Peng P.  Ultrasound-Guided Interventional Procedures in Pain Medicine: A Review of Anatomy, Sonoanatomy, and Procedures: Part VI: Ankle Joint. Reg Anesth Pain Med. 2016;41(1):99–116.

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The Ankle John Hatzenbuehler

Approach to the Joint The ankle can be a difficult joint to examine using musculoskeletal ultrasound given the small area and large number of anatomic structures. Using a systematic approach to examining the ankle can be helpful, especially when trying to discern pathologic findings from normal anatomy. The ankle is typically divided into four separate quadrants, anterior, medial, lateral, and posterior. Initially, the patient should be positioned supine on a table with the knee flexed to 45° to allow the plantar surface of the foot to rest flat on the table. This allows easy access to the anterior quadrant. The examiner should be seated on a stool with rollers at the end of the table to easily facilitate movement from the medial to lateral sides of the ankle. Alternatively, while the patient is supine, the leg may be straightened to allow free motion of the ankle. This will allow the examiner to easily manipulate the ankle and allow for active dorsal and plantar flexion to examine dynamic structures and joint mobility. Occasionally it may be helpful to lay the patient in the lateral decubitus position with the alternative leg flexed out of the way to gain easier access to the lateral or medial quadrants. Placing a small pillow or towel under the opposite side of the ankle that is being scanned may help improve probe contact with the skin. The posterior quadrant of the ankle is best examined with the patient lying in the prone position and the ankle lying just of the edge of the table.

Probe/Machine Setting and Technique The ankle joint is one of the more technically difficult joints to ultrasound due to the numerous bony prominences and J. Hatzenbuehler (*) St. Luke’s Hospital, Department of Family and Sports Medicine, Hailey, ID, USA

uneven surfaces. Linear probes set to the musculoskeletal setting with between 7.5 and 15 Mhz frequencies are the most useful. For smaller structures such as nerve evaluation, a hockey stick probe may be beneficial as well. Ample use of ultrasound gel is helpful to allow for full contact of the probe with the uneven ankle structures. Understanding the principle of anisotropy is also critical when examining the ankle as the presence or absence of anisotropy can help the examiner distinguish between tendons, ligaments, and blood vessels that are not only nearby but may be directly adjacent to or overlying each other. The use of color Doppler will also help identify the numerous vascular structures present around the ankle.

Common Pathologic Conditions Common injuries or musculoskeletal disorders of the ankle are generally identifiable using musculoskeletal ultrasound. Ligament sprains, tendon rupture, peritendinous swelling, joint effusions, and soft tissue masses are some of the most common indications for using ultrasound. Dividing the joint by anatomic location, anterior, medial, lateral, and posterior, will help systematize the evaluation and allow for the most commonly observed pathologies to be readily identified.

Anterior This quadrant is the best to assess the anterior tendons, such as the tibialis anterior (TA), extensor hallucis longus (EHL), and extensor digitorum longus (EDL) tendons (in that order medial to lateral), which are susceptible to overuse injury and presence of tenosynovial fluid (Fig. 11.1). The anterior joint line is also easily visible allowing for identification of an ankle effusion. It is possible to access the joint for injection or aspiration in this area either anterior medially or ante-

© Springer Nature Switzerland AG 2021 J. M. Daniels, W. W. Dexter (eds.), Basics of Musculoskeletal Ultrasound, https://doi.org/10.1007/978-3-030-73906-5_11

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Fig. 11.1  Lateral ankle

Achilles Flexor digitorum longus

Tibialis anterior Medial malleolus

Posterior tibialis

Extensor hallicus longus

Tibial nerve

Navicular Medial Cuneiform

Tibial artery Flexor hallucis longus

Metatarsal

Calcaneus Sustentaculum tali

Abductor hallucis

rior laterally in order to avoid the above tendons and anterior tibial artery. With slight inversion of the ankle and scanning from the anterior quadrant to the lateral quadrant, the anterior talofibular ligament (ATFL) can be identified which is commonly injured in inversion ankle sprains. The ATFL runs from the lateral malleolus anteriorly and inserts on the talus. Once identified, a dynamic scan of the ATFL tendon while performing the anterior drawer test can help identify ligament laxity and integrity. This is best accomplished with the patient lying supine and the ankle positioned just off the end of the table. The probe can be secured with one hand squeezing the tibia, and the free hand can pull anterior force on the calcaneus. Acute ATFL sprains can be visualized as either fibular hyperechoic thickening or having anechoic areas sug-

gesting partial or complete tendon disruptions (see Table 11.1).

Medial The medial tendon group consisting of the posterior tibial and flexor digitorum and hallucis longus tendons is located in this quadrant. Identification of these structures begins in a transverse plane with the probe just posterior to the medial malleolus. These tendons can be examined in both the axial and longitudinal planes. These tendons are susceptible to acute injury with partial or complete rupture or overuse injury that can cause tenosynovitis that is identified as peri-

11  The Ankle

tendinous hypoechoic fluid. Abnormal tendons will appear with either thickened fibular pattern or have hypoechoic or anechoic gaps if a partial or complete tear is present. This is also the location of the tarsal tunnel where the tibial nerve lies between the more anterior flexor digitorum longus (FDL) tendon and more posterior flexor hallucis longus (FHL) tendon. The best landmark to locate is the sustentaculum tali. The FHL and tibial nerve lie just inferiorly to this prominence on the talus (Fig. 11.2). The posterior tibial artery and veins can look like “Mickey Mouse” in this area as well. The tibial nerve can become entrapped in the retinaculum that overlies this tarsal tunnel or be compressed if there is a ganglion cyst nearby commonly causing medial foot and heel pain and numbness. Given the superficial location of the nerve in this area, a hydrodissection procedure or cyst aspiration can be performed here, which can potentially cure tarsal tunnel symptoms. The use of ultrasound for this procedure is critically important as the posterior tibial artery and vein also lie within the tarsal tunnel and are susceptible to injury with a blind injection (see Table 11.2).

Lateral As mentioned above, scanning from the anterior quadrant to the lateral quadrant, the ATFL can be visualized (Fig. 11.1). An oblique probe position may be necessary to completely visualize the length of this ligament. An anterior drawer test can help evaluate for laxity in this position. Just distal to the lateral malleolus, the calcaneofibular ligament (CFL) can be visualized by positioning the transducer from the lateral malleolus toward the calcaneus. Excessive inversion of the ankle will produce a talar tilt test and can help identify the integrity

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or laxity of the CFL if present. Posterior to the lateral malleolus, the peroneus brevis and longus tendons can be identified best in the axial plane. Just as with the medial tendons, these lateral tendons are also susceptible to acute tears and overuse injuries. Tendon pathology can again be identified by either hypoechoic peritendinous fluid or hypoechoic or anechoic within the tendon itself. Subluxation of these tendons may also occur, and dynamic ultrasound evaluation is the best way to identify this condition. With the probe secured on the tip of the lateral malleolus and directed posteriorly, either the patient can actively dorsiflex and evert the ankle or the examiner resist dorsiflexion and eversion motion to see if the peroneal tendons subluxate anteriorly over the lateral malleolus (see Table 11.3).

Posterior The posterior quadrant is best visualized with the patient lying prone and both feet hanging off the end of the table. This will allow active, unrestricted motion of the ankle and easy comparison view of the other ankle. The Achilles tendon and retrocalcaneal bursa are visualized in this quadrant. Start with the probe in a longitudinal orientation, and scan the Achilles tendon from the myotendinous junction down to its insertion on the calcaneus. Passive dorsal and plantar flexion of the ankle will give dynamic views of the Achilles tendon to help identify partial- or full-thickness tears. Orienting the probe in the transverse plane will provide the opportunity to measure Achilles tendon thickness that can be present in chronic tendinosis. Using the power Doppler setting in either the transverse or longitudinal planes in areas of thickened Achilles tendon may show neovascularization that occurs in

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Table 11.1  The ankle: anterior Patient position Patient lying supine with knees bent and foot flat on table

Transducer position and description

Transverse orientation over anterior ankle Short axis: °Find foot extensor tendons °Scan proximally to muscle tendon junction Foot flat on table with longitudinal orientation over anterior ankle recess

Long axis: Scan length of joint in anterior plane

Anterior lateral Foot flat on table with obliquely oriented probe from lateral malleolus toward talus, have patient slightly invert the ankle

Long axis Move transducer to the anterior tip of distal lateral malleolus

11  The Ankle

Picture of scan and labeled structures

135

Pitfalls/pearls Look for flexor tendon fluid as a sign of a possible tendon tear or tenosynovitis

Labeled structures: TA – tibialis anterior EDL – extensor digitorum longus EHL – extensor hallucis longus TALUS

Passively plantarflex and dorsiflex the ankle to identify joint motion Effusions and osteophytes are well seen in this view if present

Labeled structures: Tibia Anterior joint recess Talar dome Cuneiform Orient the probe obliquely off the lateral malleolus to get full ligament in view Scan length of ligament With patient lying supine and ankle off table, examiner may perform the anterior drawer test with ATFL in view to identify laxity/integrity

Labeled structures: LM – lateral malleolus ATFL – anterior talofibular ligament TALUS

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Tibialis anterior Extensor digitorum longus

Tibia

Extensor retinaculum

Achilles tendon Lateral malleolus Talus Calcaneus Cuboid Peroneus (fibularis) longus Peroneus (fibularis) brevis Metatarsal Phalanges

Fig. 11.2  Medial ankle

Anterior tibialis tendon

chronic Achilles tendinopathy. Acute injury to the Achilles tendon can be identified with either hypoechoic or anechoic gaps within the tendon or complete absence of organized fibular appearance in complete tears. Chronic changes such as hyperechoic calcifications with shadowing or the presence of insertional calcaneal spurring are also readily identified with ultrasound. The retrocalcaneal bursa can be visualized in the longitudinal plane between the Achilles and the ­calcaneus, and excess fluid may be visualized in cases of active bursitis (see Table 11.4).

Red Flags Ultrasound of the ankle is very helpful to identify fluid in the ankle joint and around tendons. That being said, it is unlikely to be able to differentiate between benign synovitis or tenosynovitis, gouty inflammation, or an infected joint. Ultrasound guidance can be used however to help aspirate any ankle effusion for synovial fluid for analysis. Given the numerous tendons around the ankle that are susceptible to injury, complete tears of tendons are possible in each quadrant. Any suspicion for complete tendon tear, especially the Achilles tendon, warrants a high clinical suspicion and thorough clinical exam. The majority of complete tendon ruptures require surgical evaluation. The plantaris

11  The Ankle

tendon is an anatomic variant not present in all patients and can be confused as an intact Achilles tendon in cases of complete Achilles tendon tear. Passive dorsal and plantar flexion of the ankle can help identify partial from complete Achilles tendon tears. Toggling the probe during evaluation of each tendon to resolve anisotropy is helpful to distinguish the presence of partial tendon tears as well. One other consideration in patients with ultrasound evidence of tenosynovitis without the appropriate history of overuse would be the presence of an underlying autoimmune disorder such as rheumatoid arthritis (RA). In acutely symptomatic patients with RA, the medial compartment tendons are commonly affected with tenosynovitis. Tibiotalar joint synovitis with hyperechoic thickening can be seen in patient with chronic RA symptoms.

Pearls and Pitfalls The majority of the anatomic structures in the ankle are very superficial in nature. Adjusting the depth and beam penetration resolution to best optimize superficial structures is highly recommended. Also using ample ultrasound gel to

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allow for complete contact of the ultrasound probe and the ankle structures will help maximize visualization. Inverting and everting the ankle to flatten out the lateral and medial sides of the ankle, respectively, will also aid in visualization. Most of the anatomic structures in the ankle are close together. Solid anatomic knowledge of the ankle is necessary to help identify specific structures. Having an anatomy book with labeled structures nearby during the ultrasound examination of the ankle is recommended. Also, dynamic active contraction of muscles can help isolate tendons and distinguish between nearby static structures. Again, strong anatomic knowledge of anatomy is helpful in this setting. The presence of anisotropy in tendons can be both helpful and harmful during ultrasound evaluation of the ankle. The presence of anisotropy in the tendons of the medial ankle, for example, can be used to distinguish the posterior tibial tendon from the posterior tibial vascular structures that are not anisotropic. That being said, tendon anisotropy can be commonly confused for partial tendon tears. Frequent toggling of the probe in areas of hypoechogenicity in tendons can help distinguish partial tears form anisotropy.

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Table 11.2  The ankle: medial Patient position Either patient lying supine with foot flat on table with inversion or patient lying in lateral decubitus position with ankle rotated laterally

Transducer position and description

Probe posterior to medial malleolus Short axis: - Scan proximally to identify muscle tendon junction

Either foot flat on table with inversion or patient lying in lateral decubitus position

Probe oriented long axis to tendons/lower leg

11  The Ankle

Picture of scan and Labeled structures

Labeled structures: MM – medial malleolus PT – posterior tibialis tendon FDL – flexor digitorum longus tendon PTA – posterior tibialis artery and (V) veins PTN – posterior tibial nerve

Labeled structures: MM – medial malleolus POST TIB – posterior tibialis tendon

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Pitfalls/pearls A small pillow under the lateral ankle may enhance medial structure visualization Look for fluid around the flexor tendon which might indicate a tendon tear or tenosynovitis Have the patient flex the toes to distinguish TP from FDL tendons Tibial nerve will have a speckled egg appearance Have patient flex great toe to identify FHL tendon and any peritendinous fluid The tibial artery and veins (PTA, V, V) can look like “Mickey Mouse”

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Table 11.3  The ankle: lateral Patient position Either foot flat on table with eversion or patient lying in lateral decubitus position. Keep patient with ankle inverted or lie patient in lateral decubitus with pillow under medial side of ankle

Transducer position and description

Long axis (to ligament) starting at lateral malleolus Long axis: °Identify the calcaneofibular ligament (CFL) Same position

Long axis: Keeping probe anchored at lateral malleolus, sweep distal end probe posteriorly to find the posterior talofibular ligament

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11  The Ankle

Picture of scan and labeled structures

Pitfalls/pearls Ample gel is recommended due to prominent bony contours Perform a talar tilt test to assess for integrity/laxity of CFL

Labeled structures: LM – lateral malleolus CFL – calcaneofibular ligament CALC – calcaneus

(continued)

J. Hatzenbuehler

142 Table 11.3 (continued) Patient position Either foot flat on table with eversion or patient lying in lateral decubitus position

Transducer position and description

Probe behind lateral malleolus Short axis:  Start either posterior to the lateral malleolus or more distally over the lateral calcaneus Patient in same position

Long axis  Scan proximally to identify muscle tendon junction  Scan distally to insertion of peroneus brevis on base of 5th metatarsal

11  The Ankle

Picture of scan and labeled structures

143

Pitfalls/pearls Look for fluid around the flexor tendon which might indicate a tendon tear or tenosynovitis Resist ankle eversion and dorsiflexion to identify subluxation if present

Labeled structures: LM – lateral malleolus PBT – peroneus brevis tendon PLT – peroneus longus tendon Look for fluid around the base of the fifth metatarsal and cortical disruption indicating possible avulsion fracture at the base of the fifth metatarsal. Slide the probe in an oblique fashion, long axis to tendon to visualize the insertion on the base of the fifth metatarsal

Labeled structures: 5TH MTB – base fifth metatarsal PBT – peroneus brevis tendon PBL – peroneus longus tendon

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Table 11.4  The ankle: posterior Patient position Patient prone with foot off the end of the exam table

Transducer position and description

Longitudinal position over Achilles Long axis:  Scan proximally to identify the myotendinous junction and distally to the insertion on the calcaneus  Identify the retrocalcaneal bursa, if present

Patient prone with foot off the table

Transverse position over Achilles Short axis: - Scan from insertion on calcaneus to myotendinous junction

11  The Ankle

Picture of scan and labeled structures

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Pitfalls/pearls Passively dorsi- and plantarflex the ankle to examine for tears of the Achilles tendon Use power Doppler setting over areas of thickened tendon to look for neovascularization Assess for excess fluid in retrocalcaneal bursa seen in bursitis

Labeled structures Proximal view: GASTROC – gastrocnemius muscle AT – Achilles tendon MYOT – myotendinous junction

Distal view: AT – Achilles tendon CALC – calcaneus Measure the size of the Achilles tendon and compare to the other side Neovascularization can be seen in this view as well Partial tears are best seen in this view

Labeled structures AT – Achilles tendon CALC – calcaneus

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Suggested Readings 1. Park JW, Lee SJ, Kim SK, et al. Ultrasonography of the ankle joint. Ultrasonography. 2017;36:321–35. 2. Ozcakar L, Kara M, Chang KV, et al. EURO-MUSCULUS/USPRM Basic scanning protocols for ankle and foot. Eur J Phys Rehabil Med. 2015;515:647–53.

J. Hatzenbuehler 3. Serban O, Badarinza M, Fodor D.  The relevance of ultrasound examination of the foot and ankle in patients with rheumatoid arthritis – a review of the literature. Med Ultrason. 2019;21(2):175–82. 4. Drakonaki E, Allen G, Watura R. Ultrasound-guided intervention in the ankle and foot. Br J Radiol. 2016;89:20,150,577. 5. Rogers CJ, Cianca J. Musculoskeletal ultrasound of the ankle and foot. Phys Med Rehabil Clin N Am. 2010;21(3):549–57.

12

Knee Ashwin N. Babu and Eric T. Chen

Approach to the Joint The ultrasound examination of the knee provides the clinician with valuable diagnostic information when combined with a systematic history and physical examination. Efficient use of ultrasound represents a rapid and accurate means of diagnosis when applied at the point of care or bedside. Dynamic maneuvers allow for assessment of anatomic structures under stress that would not otherwise be possible with other imaging modalities. A systematic approach to the ultrasound examination of the knee is recommended.

Vastus medialis

Rectus femoris Vastus lateralis

Quadriceps tendon Biceps femoris Patella

Anterior Knee The patient is placed in a supine position with the knee in 20–30° of flexion to limit anisotropy. A pillow may be placed under the knee to maintain flexion. The examiner is positioned on the side of the limb to be examined with the ultrasound machine placed across the examination table in direct line of sight. Examination of the anterior knee begins with the ultrasound probe placed in short axis or transverse to the femur, proximal to the patella. The quadriceps muscle group is visualized in short axis and consists of three layers: the superficial layer of the rectus femoris, the intermediate layer of the vastus lateralis and vastus medialis, and the deep layer of the vastus intermedius. The ultrasound probe is now rotated to a sagittal plane and translated distally until the superior pole of the patella comes into view. Here, the suprapatellar fat pad appears just deep to the quadriceps tendon in long axis. The pre-femoral fat pad appears deep to the suprapatellar fat pad and just superficial to the

A. N. Babu (*) · E. T. Chen Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA, USA e-mail: [email protected]; [email protected]

Femur Sartorius

Patellar tendon

Gracilis

Tibialis anterior

Semitendinosus Medial gastrocnemius

Extensor digitorum longus Fibularis longus Lateral gastrocnemius Tibia

Fig. 12.1  Anterior structures

femur. Knee effusions appear in the fascial planes between these two fat pads (see Figs. 12.1 and 12.2). Moving distally, the prepatellar bursa may be examined by placing the ultrasound probe directly over the patella. Care should be taken to avoid compressing the superficial tissues with the probe, as even slight pressure can displace any fluid in this bursa. The prepatellar bursa is not usually visible in patients without pathology. The patellar tendon

© Springer Nature Switzerland AG 2021 J. M. Daniels, W. W. Dexter (eds.), Basics of Musculoskeletal Ultrasound, https://doi.org/10.1007/978-3-030-73906-5_12

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Fig. 12.2 Cross-sectional anatomy of the knee Patellar tendon Infrapatellar fat pad Lateral meniscus

Medial meniscus Medial collateral ligament Sartorius Saphenous nerve Gracilis Semimembranosus Semitendinosus

Lateral collateral ligament Popliteus Biceps Peroneal nerve Popliteal artery Lateral head gastrocnemius Tibial nerve

Medial head gastrocnemius

may now be examined in long axis and short axis through its entire length and width from the inferior pole of the patella to the tibial tubercle. The deep infrapatellar bursa and Hoffa’s fat pad are located deep to the patellar tendon and are best visualized in a sagittal plane. To visualize the femoral trochlea, the patient remains supine with the knee placed in end-range flexion. The ultrasound probe is placed short axis to the femur at the level of the trochlea to facilitate examination of the articular cartilage.

Medial Knee The patient remains in the supine position with the knee flexed to approximately 30 degrees. The patient is asked to externally rotate at the hip, exposing the medial knee. The examiner remains in the same position. The transducer is oriented in a coronal plane to visualize medial collateral ligament (MCL) in long axis. The superfi-

cial MCL is examined from its proximal attachment at the medial femoral epicondyle through its broad distal attachment at the medial tibia. The deep layer of the MCL is comprised of menisco-femoral and menisco-tibial components which can be distinguished from the superficial layer. The medial meniscus is visible deep to the MCL. Near the tibial attachment of the MCL, translation of the probe anteroinferiorly will reveal the pes anserine tendon insertion along the medial aspect of the proximal tibial diaphysis. Slight oblique rotation of the probe will bring the pes anserine tendons into a true short-axis view. The medial patellofemoral ligament (MPFL) is identified by placing the ultrasound probe in an axial plane between the superomedial border of the patella and the medial femoral epicondyle. The inferomedial geniculate neurovascular bundle is located deep to the distal MCL and appears as a group of small hypoechoic circles, which may show pulsatile flow under Doppler examination. The saphenous nerve is located within the adductor canal of the medial thigh, which is

12 Knee

formed by the adductor magnus/longus, vastus medialis, and sartorius. It is best visualized in short axis next to the femoral artery and vein. See Table 12.1 Knee. The patient remains in the supine position with the knee flexed to approximately 30 degrees. The patient is asked to internally rotate at the hip, exposing the lateral knee. Alternatively, the patient may be placed in a lateral decubitus position with the lateral knee facing up. The examiner remains in the same position. Evaluation of the lateral knee begins with visualization of Gerdy’s tubercle on the tibia, which can be found lateral to the tibial tubercle. In a long-axis orientation, the IT band is traced proximally from its distal insertion at Gerdy’s tubercle as it passes over the lateral femoral condyle. The lateral collateral ligament (LCL) is examined by extending the knee and placing the transducer in plane with the fibular head and lateral femoral condyle. The biceps femoris tendon also inserts at the fibular head and can be distinguished from the LCL by following the biceps tendon to its myotendinous junction in the posterior thigh. The popliteus tendon is visualized in short axis within its bony groove, deep to the LCL and proximal to the lateral joint line. The lateral meniscus can be seen deep to the LCL. The fibular (peroneal) nerve is best visualized in cross-­ section curving around the fibular head. It is commonly identified posterior and inferior to the fibular head in this location. Tracing the nerve distally, the common fibular nerve is noted to bifurcate into deep and superficial divisions. The common fibular nerve may also be identified during the posterior knee exam as are branches from the sciatic nerve. Finally, the proximal tibiofibular joint is examined by placing the transducer transverse to the fibular head and the lateral tibial condyle. The proximal tibiofibular ligament is visualized here traversing the joint.

Posterior Knee The patient is placed in a prone position with the knee fully extended. In some cases, placing the knee in slight flexion may facilitate visualization of a Baker’s cyst and its communication with the joint.

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The examiner may keep the same position and reach over to the opposite side of the table to examine the posterior structures. It may be necessary to stand or sit on the edge of the exam table for quality and comfort. The ultrasound machine remains on the far side of the table. The posterior knee exam is started by placing the transducer in an axial plane just proximal to the popliteal crease. On the medial aspect of posterior knee, the most superficial structure will be the semitendinosus tendon in short axis. Deep to the semitendinosus will be the semimembranosus tendon. The sartorius and gracilis tendons can be found passing medially to the hamstring tendons. As the semimembranosus tendon is followed distally, the tendon of the medial head of the gastrocnemius appears lateral to the semimembranosus tendon. A Baker’s cyst typically is located between these two tendons. The medial gastroc may also be traced to its myotendinous junction distally. At the level of the popliteal fossa, the sciatic nerve is usually already divided into the tibial and common fibular nerves. The tibial nerve can be identified in close relation to the popliteal artery and vein. The tibial nerve is followed proximally until it joins with the common fibular nerve to form the distal sciatic nerve. The common fibular nerve may also be followed distally as it travels laterally around the fibular head, where it divides into the deep and superficial branches. The biceps femoris may be examined at the posterolateral aspect of the knee. Both long and short heads of the biceps femoris can be traced to their proximal myotendinous junctions. The distal biceps femoris tendon may also be followed to its insertion at the fibular head. As the biceps tendon tapers distally, the lateral gastroc tendon will come into view and can be traced distally to its myotendinous junction. Finally, the transducer is placed in an axial plane over the popliteal crease to visualize the posterior femoral condyles, tibial plateaus, and articular cartilage. The posterior horns of the medial and lateral menisci may also be examined by orienting the transducer in a sagittal plane and anchoring the transducer over the femoral condyle and tibial plateau as bony landmarks. The PCL may also be evaluated here by placing the transducer in a longitudinal oblique plane just

A. N. Babu and E. T. Chen

150 Table 12.1 Knee Patient position Anterior superior knee Patient in supine position, knee flexed 20–30°, with pillow under knee

Transducer position and description

Longitudinal or long-axis view Probe superior to patella

Transverse or short-axis view Probe superior to patella

12 Knee

Picture of scan and labeled structures

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Pearls/pitfalls Identification of the suprapatellar recess is easier when an effusion is present Note three layers of quadriceps tendon Examine the medial and lateral recesses of the suprapatellar bursa, as fluid may collect there

Labeled structures PAT—patella QT—quadriceps tendon SPR—suprapatellar recess SPFP—suprapatellar fat pad FEMUR

Labeled structures FEMUR QT—quadriceps tendon VMED—vastus medialis VLAT—vastus lateralis VINT—vastus intermedius (continued)

A. N. Babu and E. T. Chen

152 Table 12.1 (continued) Patient position Anterior superior knee Patient in supine position, end-range flexion

Transducer position and description

Short-axis view Probe just above patella

Anterior inferior knee Patient in supine position, knee flexed 20–30°, with pillow under knee

Long-axis view Probe inferior to patella

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Picture of scan and labeled structures

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Pearls/pitfalls The articular cartilage is hypoechoic and can be mistaken for fluid in the suprapatellar bursa

Labeled structures QT—quadriceps tendon TROCHLEA ART CART—articular cartilage

Labeled structures PAT—patella PT—patellar tendon TIB—tibia HFP—Hoffman’s fat pad (continued)

A. N. Babu and E. T. Chen

154 Table 12.1 (continued) Patient position

Transducer position and description

Short-axis view Probe inferior to patella Medial knee Patient is supine, with knee flexed 20–30°, with pillow under knee, knee slightly externally rotated

Long-axis view Probe over medial joint line

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Picture of scan and labeled structures

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Pearls/pitfalls

Labeled structures PT—patellar tendon Having an assistant apply valgus stress to the knee can allow for better visualization of MCL pathology. Can also support lateral knee with pillow for gentle valgus stress

Labeled structures MCL—medial collateral ligament MM—medial meniscus TIBIA FEMUR (continued)

156 Table 12.1 (continued) Patient position

A. N. Babu and E. T. Chen

Transducer position and description

Long-axis view—pes Slide transducer distally over joint line

Short-axis view—pes As above

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Picture of scan and labeled structures

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Pearls/pitfalls The pes anserine “goose foot” is best visualized by orienting the probe in an oblique fashion, following the tendons of the sartorius, gracilis, and semi-tendinosis (in that order anterior to posterior). This is best accomplished by having the patient gently contract those muscles (have assistant place hand over medial malleolus and ask the patient to apply pressure against this)

Labeled structures TIBIA PES—pes anserine

Labeled structures TIBIA PES—pes anserine (continued)

A. N. Babu and E. T. Chen

158 Table 12.1 (continued) Patient position Lateral knee Patient supine, knee slightly internally rotated and flexed at 20–30°

Transducer position and description

Long-axis view Lateral joint line

Long-axis view Distal probe at fibular head, rotate proximal probe anteriorly to evaluate LCL

12 Knee

Picture of scan and labeled structures

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Pearls/pitfalls Use Gerdy’s tubercle to help with identification of the ITB Can evaluate for meniscal cyst: have patient flex knee, transducer on joint line

Labeled structures ITB—iliotibial band GT—Gerdy’s tubercle LFC—lateral femoral condyle LAT JT—lateral joint line TIB—tibia The popliteus tendon can be evaluated in short axis at the LFC

Labeled structures POP T—popliteus tendon (arrow) LFC—lateral femoral condyle LCL—lateral collateral ligament FH—fibular head TIB—tibia (continued)

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Table 12.1 (continued) Patient position Posterior knee Patient is in prone (face down) position, knee completely extended May place a small pillow under tibia for patient comfort

Transducer position and description

Long-axis view, medial

To obtain this view, patient is supine with the leg slightly internally rotated, knee slightly flexed, supported by a pillow

Long-axis view, lateral

12 Knee

Picture of scan and labeled structures

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Pearls/pitfalls A useful technique to more easily identify hamstring tendons is to have the examiner or assistant resist a gentle contraction (knee flexion)

Labeled structures SMT—semimembranosus tendon STT—semitendinosus tendon TIB—tibia MEN—meniscus MFC—medial femoral condyle Slide the probe laterally to view the biceps femoris tendon which will insert distally into the fibular head The biceps tendon can also (and perhaps more easily) be viewed with the patient’s knee supported medially in slight flexion; examiner approaches from the lateral aspect of the knee. (second picture) again; slight resistance (contract hamstrings) might aid in visualizing the tendon

Labeled structures FH—fibular head BT—biceps femoris tendon LFC—lateral femoral condyle MEN—meniscus TIB—tibia

(continued)

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Table 12.1 (continued) Patient position

Transducer position and description

Short-axis view, medial

Short-axis view, midline

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Picture of scan and labeled structures

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Pearls/pitfalls When assessing for a Baker’s cyst, note that, due to anisotropy, it may be challenging to identify both the semimembranosus tendon and the medial head of the gastrocnemius tendon in the same axial image

Labeled structures MFC—medial femoral condyle SMT—semimembranosus tendon STT—semitendinosus tendon SN—sural nerve MHG—medial head gastrocnemius Slide the probe laterally (arrow) to visualize posterior structures Use Doppler imaging to visualize flow through the popliteal vasculature

Labeled structures MFC—medial femoral condyle LFC—lateral femoral condyle MHG—medial head of gastrocnemius LHG—lateral head of gastrocnemius TN—tibial nerve PA—popliteal artery PV—popliteal vein (continued)

A. N. Babu and E. T. Chen

164 Table 12.1 (continued) Patient position Transducer position and description To obtain this view, the patient is supine, leg slightly internally rotated, knee slightly flexed and supported by a pillow

Short-axis view, lateral

Short-axis view, anterior, lateral

12 Knee

Picture of scan and labeled structures

Labeled structures FH—fibular head CPN—peroneal nerve LHG—lateral head of gastrocnemius

Labeled structures FH—fibular nerve CPN (arrow)—common peroneal nerve ANT—anterior

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Pearls/pitfalls Note that the peroneal nerve (fibular nerve) wraps around the head of the fibula and can be in close approximation to the fibula. Identifying the nerve can be challenging as it has a somewhat sinuous course, so the examiner must use a light/deft touch (and plenty of gel!) The nerve is often seen best using a more oblique probe position. The examiner approaches this from the lateral aspect of the knee

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medial to midline in the popliteal fossa with slight inferolateral rotation (see Figs. 12.2, 12.3, and 12.4). Semitendinosus

Probe Selection/Settings Linear transducers capable of higher frequencies are preferred for anterior, medial, and lateral examinations. Posterior examinations may require lower frequencies for better visualization. Image optimization of depth and focus will be variable depending on the structure of interest.

Gracilis

Tibial ar ter y Tibial nerve

Semimembranosus Femur

Biceps femoris Common fibular nerve Popliteus

Common Pathologic Conditions

Tibia

Baker’s Cyst A Baker’s cyst will typically be located in the posterior knee between the semimembranosus and medial gastroc tendons. The base of the cyst is often smaller than the superficial portion, although a stalk connecting the base with the posterior joint is not always seen. When making the diagnosis of Baker’s cyst, it is important to locate the cyst between medial head of the gastrocnemius and the semimembranosus; otherwise, alternative pathology (masses) cannot be completely ruled out. If aspiration of the Baker’s cyst is considered, it is important to identify the popliteal artery, popliteal vein, and tibial nerve. Doppler ultrasound can assist in identifying the popliteal artery as a non-compressible pulsatile vessel located near the midline of the popliteal fossa.

Plantaris Fibula

Soleus

Fig. 12.3  Posterior deep structures of the knee

Sartorius

Meniscal Tear

Semitendinosus Semimembranosus

Ultrasound may be used to assist in diagnosis of meniscal tears which appear as hypoechoic or anechoic clefts or defects in the meniscus extending to the articular surface. Cook et al. [1] demonstrated 91.2% sensitivity and 84.2% specificity of ultrasound in the diagnosis of meniscal tears confirmed by arthroscopy. Park et al. [2] found ultrasound correctly identified the presence and absence of meniscal tears in 86% and 85% of cases, respectively, compared to MRI.

Iliotibial band Lateral collateral ligament Medial head gastrocnemius

Patellar Tendinopathy The hallmark findings of patellar tendinopathy include tendon thickening, hypoechoic tendon segments, and neovascularization under Doppler imaging.

Fig. 12.4  Posterior structures of the knee

Femur Biceps femoris Medial collateral ligament Lateral head gastrocnemius

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MCL Injury

Patellar Dislocation

Ultrasound examination may demonstrate discontinuity of the MCL with or without surrounding fluid collection in cases of suspected MCL injury. Partial tears may affect the superficial or deep layers of the MCL. Dynamic testing of the MCL may be performed by application of valgus stress to knee while visualizing the MCL and medial joint line.

The medial retinacular structures may be injured in cases of lateral patellar dislocation, the most common direction of patellar dislocation. Felus et  al. [8] demonstrated the utility of ultrasound in diagnosing tears of the medial patellofemoral ligament (MPFL) and osteochondral lesions associated with patellar dislocation. Ultrasound examination may reveal a knee effusion, the MPFL may appear in discontinuity, and there may be fluid collection surrounding the injured ligament.

IT Band Syndrome Fluid collection or bursal distension may be visualized deep to the IT band as it passes superficially over the lateral femoral condyle. The IT band itself may appear thickened. Dynamic knee flexion and extension may reveal snapping of the IT band in this region.

Osgood-Schlatter’s Disease Vreju et al. used ultrasound to show changes at the distal portion of the patellar tendon and tibial tuberosity in an athlete with Osgood-Schlatter’s disease [3]. In addition to tendon thickening, ultrasound may reveal focal tendon hypoechogenicity, neovascularization, and cortical irregularity at tibial tuberosity. Similarly, ultrasound may be used to detect changes in characteristic of Sinding-Larsen-Johansson syndrome at the inferior pole of the patella, a disease process similar to Osgood-Schlatter’s disease [4].

Red Flags While ultrasound can be used to examine osseous structures, X-ray is the modality of choice when fracture is suspected. A large pulsatile mass in the posterior knee may be a popliteal artery aneurysm, which may require formal vascular assessment. Septic joints may present with joint effusion, erythema, pain, and systemic signs of infection. Joint aspiration will aid in diagnosis, but any suspicion of septic joint requires urgent medical evaluation and treatment.

Pearls and Pitfalls

Suprapatellar effusions may coalesce in the medial or lateral recesses of the suprapatellar bursa. Have the patient activate the quadriceps by pushing the back of the knee down into the table, or have an assistant milk the bursa to bring the effusion into better view. Pes Anserine Bursitis Dynamic examination of the medial knee through application of valgus force may reveal increased laxity in MCL Hypoechoic bursal distension overlying the pes anserine ten- injuries. Comparison to the contralateral knee may be useful dons may be indicative of pes anserine bursitis. Ultrasound-­ in assessing baseline stability. guided cortisone injection may be performed to this structure, Utilize Doppler imaging to identify and confirm the locaif the bursitis is felt to be clinically significant [5]. tion of the popliteal artery prior to Baker’s cyst aspiration. Recognize the limitations of ultrasound for imaging deep intra-articular structures of the knee. Ultrasound provides an Quadriceps Tendon Rupture incomplete assessment of the cruciate ligaments and c­ artilage lesions. MRI is indicated if the clinical evaluation suggests Bianchi et al. and La et al. established ultrasound as a useful these injuries may be present. tool for detecting full and partial quadriceps tendon ruptures A potential source of posterior knee pain could be gas[6, 7]. In cases of full-thickness tears, tendon retraction may trocnemius injury. Follow the gastrocnemius tendons distally be visualized under ultrasound and often correlates with pal- to their myotendinous junctions to assess for hematoma. pable defect of the quadriceps in the physical exam.

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Confirm pathologic findings in orthogonal planes to reduce the rate of false positive findings. Tendons are prone to anisotropy, which may appear similar to a tendon tear.

References 1. Cook J, Cook C, Stannard J, Vaughn G, Wilson N, Roller B, et al. MRI versus ultrasonography to assess meniscal abnormalities in acute knees. J Knee Surg. 2014;27(04):319–24. 2. Park G-Y, Kim J-M, Lee S-M, Lee MY. The value of ultrasonography in the detection of meniscal tears diagnosed by magnetic resonance imaging. Am J Phys Med Rehabil. 2008;87(1):14–20. 3. Vreju F, Ciurea P, Rosu A.  Osgood-Schlatter disease--ultrasonographic diagnostic. Med Ultrason. 2010;12(4):336–9.

A. N. Babu and E. T. Chen 4. Valentino M, Quiligotti C, Ruggirello M. Sinding-larsen-johansson syndrome: a case report. J Ultrasound. 2012;15(2):127–9. 5. Yoon HS, Kim SE, Suh YR, Seo Y-I, Kim HA, Young RS, et  al. Correlation between ultrasonographic findings and the response to corticosteroid injection in pes anserinus tendinobursitis syndrome in knee osteoarthritis patients. J Korean Med Sci. 2005;20(1):109–12. 6. Bianchi S, Zwass A, Abdelwahab IF, Banderali A. Diagnosis quadriceps value of tears tendon of the of the knee: of sonography. Ajr. 1994; 7. La S, Fessell D, Femino J, Jacobson J, Jamadar D, Hayes C. Sonography of traumatic quadriceps tendon tears with surgical correlation. J Ultrasound Med. 2015;34(5):805–10. 8. Felus J, Kowalczyk B, Lejman T.  Sonographic evaluation of the injuries after traumatic patellar dislocation in adolescents. J Pediatr Orthop. 2008;28(4):397–402.

13

Hip Lauren Elson, Raymond Chou, and David Robinson

Probe Selections and Presets A linear transducer at 10–13 MHz will allow the best visualization for thin patients, especially for the lateral hip structures. A curvilinear 5-MHz probe is often necessary for muscular or obese patients to allow adequate penetration and visualization of the joint and deeper hip structures. Generally, it is best to start with a high-frequency linear transducer and then switch to a curvilinear transducer if unable to visualize adequately. Use the highest-frequency transducer that provides adequate penetration. If your machine has hip presets, start with those. If the hip joint is deeper than 6 cm, then a 5-MHz curvilinear transducer set at 10–12 cm of depth with two focal zones will give the best visualization.

Approach to the Joint Anterior Hip The patient should be positioned supine on the examination table with the leg relaxed, in slight external rotation and slight flexion at the knee, without flexion at the hip. The examiner is seated on an adjustable rolling stool by the side of the hip that is being examined. The ultrasound screen should be placed toward the head of the patient or across the table for easiest viewing (Table 13.1). Place the transducer in a longitudinal (sagittal) plane, long-axis view, near the inguinal ligament. Slide the transL. Elson (*) Harvard Medical School, Somerville, MA, USA e-mail: [email protected] R. Chou Spaulding Rehabilitation Hospital, Physical Medicine & Rehabilitation, Charlestown, MA, USA D. Robinson Spaulding Rehabilitation Hospital, Department of Physical Medicine and Rehabilitation, Charlestown, MA, USA

ducer laterally and medially to identify the hip joint and femoral vessels. Then, while over the femoral head, turn the transducer so that it is parallel with the femoral neck in an oblique longitudinal plane. The acetabulum can then be identified as a thin cusp cranial to the femoral head; the labrum is attached to it and appears as a triangular and mixed echogenic structure. The femoral head flattens to form the femoral neck, and overlying this is the joint capsule. If osteoarthritis is present, there may be an irregular appearance of the femoral head, narrowing of the joint space, and osteophyte formation on the acetabulum. Synovitis may appear as a thickened hypoechoic structure within the joint space (average thickness is 5.2 mm; pathologic thickness > 8–9 mm) and may be mistaken as a large joint effusion. Turn on the Doppler setting and note the amount of vascularity present. A large amount of vascularity is indicative of synovitis, as opposed to the absence of vessels in an effusion. Both may be present. “Femoral acetabulum impingement” is a term used to describe some factors that may be associated with premature arthritis of the hip. While best identified using radiographs, musculoskeletal ultrasound may be useful in identifying incongruence of the femoral head and the acetabulum. While most patients have a combination, there are two distinct types of impingement: cam (the femoral neck is too thick or the “ball is too big for the socket”) and pincer (the acetabulum is too large or the “socket is too big for the ball”). The cam-shaped (thickened) femoral neck is less distinct and almost blends in with the femoral head. The joint capsule closely adheres to the femoral neck. The acetabulum is distinct and pointed in appearance. The labrum is frequently blunted and detached from the acetabulum. These patients may require diagnostic injection to the joint space if it is unclear whether impingement is the pain generator. The entire labrum cannot be seen with ultrasound, but the anterior labrum is easily visualized. The normal labrum is triangular and slightly echogenic and is firmly attached to the acetabulum. An acute disruption of the labrum is evidenced

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Table 13.1  Hip: anterior Patient position Anterior hip Patient should be supine on the examination table, with the leg relaxed and with no hip flexion The hip should be slightly externally rotated and knee slightly flexed Examiner is seated on an adjustable, rolling stool, on the side of the hip that is being examined Ultrasound screen should be placed toward the head of the patient or across the table for easiest viewing

Transducer position and description

Lean patients: the 10–13-MHz linear probe may be sufficient. For obese, muscular patients and deep structures: 5-MHz curved probe

Oblique longitudinal or long axis, over anterior hip parallel to femoral neck

Short axis over femoral vessels

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Picture of scan and labeled structures

Pearls/pitfalls Evaluate • Femoroacetabular joint • Labrum – anterior portion can be visualized • Iliopsoas tendon and bursa • Joint capsule (average width 5 mm; >8 mm  =  synovitis) Slide the probe both medially and laterally to assess the entire anterior joint capsule and iliopsoas tendon Slide probe distally to evaluate the insertion of the iliopsoas on the lesser trochanter Note that the anterior hip examination will require manipulation of focal zone, gain, and depth. If only one probe is used, a curvilinear probe might be the better choice

Labeled structures: PS – iliopsoas FH/FN – femoral head/femoral neck ACET – acetabulum L – labrum JC – joint capsule

More medially in transverse axis, note the femoral vessels and nerve. Doppler may be used to confirm these. Remember: N-A-V-E-L (nerve, artery, vein, empty space, lymphatics)

Labeled structures: FA – femoral artery FV – femoral vein(s) FN – femoral nerve

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Table 13.1 (continued) Patient position

Transducer position and description

Short axis over hip joint

Long axis over ASIS

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Pearls/pitfalls

The presence of effusion should be confirmed in both short and long axis For hip joint injection, the examiner usually can inject into the joint capsule overlying the femoral neck Using a 3.5-cm, 22-gauge spinal needle allows for adequate depth penetration to hip joint for most injections Labeled structures: AIIS – anterior inferior iliac spine RF – rectus femoris tendon A – acetabulum FH – femoral head

Don’t forget: you can always palate a structure to guide where you put the probe – use surface anatomy. This can be particularly useful in finding the ASIS Labeled structures: ASIS – anterior superior iliac spine SAR – sartorius

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Table 13.1 (continued) Patient position

Transducer position and description

Short axis over ASIS Note that scanning of the ASIS and surrounding structures can be done as part of the anterior or lateral hip examination The patient can be placed either in a supine or lateral decubitus position

Long axis to ITB, TFL

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Picture of scan and labeled structures

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Pearls/pitfalls

Labeled structures: G MED – gluteus medius SAR – sartorius ASIS – anterior superior iliac spine IL – iliacus

These two views, of the ASIS and surrounding structures, can also be done as part of the anterior hip examination. The scanning picture demonstrates this Again, the examiner should utilize anatomic landmarks by palpating the ASIS to guide probe placement These views might be better viewed with a linear probe and require scanning superiorly, posteriorly, as well as medially and laterally to optimize the images The short-axis view is an excellent approach to injection of the lateral femoral cutaneous nerve (meralgia paresthetica)

Labeled structures ASIS – anterior superior iliac spine GMED – gluteus medius TFL – tensor fascia lata ITB – iliotibial band

(continued)

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Table 13.1 (continued) Patient position

Transducer position and description

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Picture of scan and labeled structures

Labeled structures G MED – gluteus medius TFL – tensor fascia lata SAR – sartorius LFCN – lateral femoral cutaneous nerve

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Psoas Iliacus Iliac crest Femoral nerve

Sacrum Hip joint

Anterior superior iliac spine Femoral Artery Tensor fascia lata

Pectineus Inguinal ligament Symphysis Pubis Adductor longus

Vastus lateralis

Sartorius

Rectus femoris

Gracilis

Femur

Vastus medialis

Fig. 13.1  Anterior hip

by a rounded or blunted appearance and a thin hypoechoic space between the acetabulum and the labrum. The iliopsoas tendon and bursa can also be easily visualized with musculoskeletal ultrasound superficial to the hip joint. Start with the transducer in a transverse or short-axis (horizontal) position near the inguinal ligament. Confirm the center of the hip joint at the femoral head, and observe that the femoral vessels are medial to the visual field. Note the round appearance of the psoas major muscle situated here. Then turn the transducer to the longitudinal or short-axis (horizontal) position. The iliopsoas tendon lies directly superficial to the hip joint and normally has a gray, mixed echogenic appearance similar to the rectus femoris muscle directly superficial to it. The iliopsoas bursa is normally not seen unless it is distended because of inflammation or infection. When it is present, it is a thin, anechoic black space directly superficial to the hip joint and deep to the iliopsoas tendon. Figure 13.1 demonstrates the basic anterior hip anatomy in the frontal or coronal plane.

Lateral Hip The patient should be in decubitus position on the examination table, hips slightly flexed to provide stability and a pil-

low placed between the knees to reduce discomfort. The examiner is seated on an adjustable rolling stool posterior to the patient and next to the hip that is being examined. The ultrasound screen should be placed toward the head of the patient or across the table for easiest viewing. Place the transducer in a longitudinal (coronal) plane near the widest part of the hip. Slide the transducer anteriorly and posteriorly while angling the beam as needed to identify the greater trochanter. Turn the transducer to a short-axis (transverse) position to confirm the center of the trochanter. Next, slide the transducer cranially and caudally to identify the top of the lateral femur, where you will see an apex of bone between the anterior and lateral facets of the greater trochanter. With the transducer in a long-axis plane and your image centered on the posterosuperior aspect of the lateral femur, identify the margin between the trochanter and the less hyperechoic iliotibial band. This is the trochanteric (or subgluteus maximus) bursa. Normally, the trochanteric bursa is a potential space and measures less than 2  mm. When inflamed, it is common to see effusions greater than 5–10 mm. Next, identify the gluteus medius insertion and gluteus medius bursa. Start with the transducer in a longitudinal (coronal) plane near the most prominent part of the hip. Slide the transducer anteriorly and posteriorly and angle the beam to identify the superior greater trochanter. Turn the transducer to a short-axis (transverse) position to confirm the center of the trochanter, and then slide the transducer cranially and caudally to identify the insertion of the gluteus medius tendon on the lateral facet of the greater trochanter. The gluteus medius tendon is echogenic in appearance and is deep to the iliotibial (IT) band, inserting on the lateral facet (anterosuperior portion) of the greater trochanter. The bursa is normally not seen because it is a potential space, but when inflamed it is anechoic in appearance, just deep to the gluteus medius tendon and anterior to the trochanteric bursa. To identify the piriformis muscle insertion, start with the transducer in a longitudinal or long-axis (coronal) plane near the posterior proximal femur. Slide the transducer anteriorly and posteriorly and angle the beam to identify the posterosuperior femur. Turn the transducer to a short-axis (transverse) position to identify the fibers of the piriformis tendon as it inserts on the posterosuperior femur, deep to the gluteus maximus muscle and parallel to the gluteus medius tendon. The normal appearance of this tendon is slightly hyperechoic and appears almost indistinguishable from the gluteus medius tendon. When inflamed, its insertion is densely hypoechoic and the remainder of the muscle is mildly hypoechoic. The sciatic nerve has a honeycomb appearance and is located deep to the piriformis, near its origin. See Fig.  13.2 and Table 13.2 for the anatomy of the lateral hip.

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Iliac crest

Femoral head

Gluteus minimus

Greater trochanter

Sacrum

Superior-posterior facet

Sacrotuberous ligament

Piriformis Gluteus medius Lateral facet Posterior facet

Ischium Anterior facet Gluteus minimus Femur

Gluteus medius

Sciatic nerve

Piriformis Greater trochanter

Ischium

Quadratus femoris

Ischial tuberosity

Femur

Semitendinosus Biceps femoris

Iliotibial band

Adductor magnus

Vastus lateralis

Gricilis

Tensor fascia lata Iliotibial band

Fig. 13.3  Posterior hip

Fig. 13.2  Lateral hip

Posterior Hip The patient should be in prone position on the examination table, feet hanging off the table and a pillow placed under pelvis for mild hip flexion. The examiner is seated on an adjustable rolling stool next to the hip that is being examined. The ultrasound screen should be placed toward the head of the patient or across the table for easiest viewing. Place the transducer in a transverse (axial) plane over the midline of the sacrum. Slide the transducer laterally to first identify the posterior sacral foramina and then the sacroiliac joint. As you slide the transducer cranially and caudally over the sacroiliac joint, note the wider superior fibrocartilage articulation of the sacroiliac joint when compared to its narrower inferior true synovial articulation. Next, identify the piriformis muscle. With your transducer positioned in the transverse (axial) plane over the sacroiliac joint, scan caudally over the greater sciatic foramen. Angle your probe inferolateral to have the medial end of the probe over the foramen and lateral end pointing toward the greater trochanter to evaluate the piriformis in long axis. Note the muscle bulk medial to the ilium transition to tendon laterally at its attachment to the greater trochanter. In cases of piriformis pathology, muscle hypertrophy is often present when comparing the symptomatic side to the asymptomatic side.

The sciatic nerve should then be evaluated. Palpate the ischial tuberosity and place your probe between it and the greater trochanter in the transverse (axial) plane. Note the sciatic nerve, which appears as a hyperechoic oval between the bony landmarks and inferior to the gluteus maximus. Next, scan medially to directly over the ischial tuberosity, and observe the conjoint tendon of the long head biceps femoris and semitendinosus superolaterally. The semimembranosus can be seen superomedial to the tuberosity. Proximal hamstring tendinopathy presents as thickening and peritendinous hypoechoic fluid. For posterior hip anatomy, see Fig. 13.3; see also Table 13.3.

Common Problems Are Blood Vessels in the Path of My Needle? First, visualize the femoral vessels in both short- and long-­ axis views. Use color flow Doppler to ensure that the femoral artery and vein are medial to your injection path. Next, identify the lateral femoral circumflex artery as it crosses the joint capsule in various locations. In a long-axis view, use color flow Doppler to identify the location when mapping the potential path your needle will take to the joint capsule or to the iliopsoas bursa. Lastly, determine if an inferior or superior approach is preferable to avoid vessels. The inferior approach is generally the easiest as it approaches the bursa and joint capsule per-

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180 Table 13.2  Hip: lateral Patient position Lateral hip The patient should be in decubitus position on the examination table, hips slightly flexed to provide stability and a pillow placed between the two knees to reduce discomfort. Examiner is seated on an adjustable, rolling stool, on the side of the hip that is being examined

Transducer position and description

The ultrasound screen should be placed toward the head of the patient or across the table for easiest viewing

Long axis, over the greater trochanter

Transverse or short axis, over the greater trochanter

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Picture of scan and labeled structures

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Pearls/pitfalls Begin exam by palpating the greater trochanter and placing probe long axis to femur over the trochanter

When inflamed, the piriformis tendon insertion tendon is usually indistinguishable from the gluteus medius because it becomes hypoechoic (dark) Visualizing the contralateral side is useful to confirm abnormal findings on the affected side Is trochanteric bursitis the source of pain? Lateral hip pain can come from the gluteus medius bursa, the trochanteric (subgluteus maximus) bursa, insertional tendon pathology or can be referred from distant structures Labeled structures (both screenshots) GRTR – greater trochanter ITB – iliotibial band

Evaluate °Greater trochanteric bursa (usually 5 mm  =  effusion) °Gluteus medius muscle deep to IT band, bursa deep to muscle; usually a potential space, if present, may indicate inflammation If you see fluid in the trochanteric bursa, do not assume that is the only area of inflammation. Concurrently evaluate the gluteus medius tendon and bursa for inflammation

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Table 13.2 (continued) Patient position

Transducer position and description

Long axis to gluteus minimus Oblique to femur/trochanter

Short axis to gluteus minimus tendon

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Picture of scan and labeled structures

Pearls/pitfalls Once the examiner has located the greater trochanter, continually return to this known view of the trochanter to get your bearings or as your “home base” for examining the lateral hip. Then angle the probe both anteriorly, to find the gluteus medius, and posteriorly to find the gluteus medius Look at both tendons in short and long axis Beware of anisotropy here. It is unusual to find fluid in the bursae around the trochanter. More commonly there will be findings consistent with enthesopathy or chronic tendinopathy

Labeled structures GRTR – greater trochanter G MIN – gluteus minimus muscle T – tendon G MED T – gluteus medius tendon

Labeled structures TFL – tensor fascia lata GRTR – greater trochanter GMIN T – gluteus medius tendon

(continued)

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184 Table 13.2 (continued) Patient position

Transducer position and description

Long axis to gluteus medius tendon Oblique to trochanter

Short axis to gluteus medius tendon

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Picture of scan and labeled structures

Labeled structures G MED T – gluteus medius tendon GT – greater trochanter

Labeled structures GMIN – gluteus minimus GMED T – gluteus medius tendon GRTR – greater trochanter

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Pearls/pitfalls Tears and tendinopathy of the gluteus medius tendon can be a frequent source of greater trochanteric pain. The examiner should be aware that there are two heads of the gluteus medius tendon – on the lateral facet and the superior posterior facet. The lateral facet insertion is much larger than the superior posterior

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186 Table 13.3  Hip: posterior Patient position Transducer position and description Posterior hip Patient should be in prone position on the examination table; feet can be hanging off the table and a pillow placed under pelvis for mild hip flexion. Examiner is seated on an adjustable, rolling stool, on the side of the hip that is being examined Ultrasound screen should be placed toward the head of the patient or across the table for easiest viewing

Short-axis view (to SI joint)

Often, a curvilinear probe will provide a better look at the posterior hip, particularly for deeper structures such as the sciatic nerve

Long-axis view (to piriformis)

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Pearls/pitfalls Evaluate °Sacroiliac joint °Piriformis °Sciatic nerve – between the greater trochanter and ischial tuberosity °Proximal hamstring origin

Begin the posterior hip examination with the sacrum and SI joint. Use landmarks and palpation to find the PSIS and use that as your reference point or “home base”

Labeled structures SAC – sacrum SIJ – sacroiliac joint PSIS – posterior superior iliac spine SF – sacral foramina

Note that as you scan laterally, the ilium will drop away rapidly. You will need to manipulate the gain, depth, and focal zone to optimize images in the posterior hip as the structure travel superficial to deep

When evaluating the SI joint, particularly when planning an approach to an injection, be sure to distinguish the neural foramina

The piriformis is deep but can be easily distinguished moving under the gluteus with passive rotation of the hip (best done with an assistant). Scan the entirety of the piriformis; sacrum to greater trochanter

Labeled structures SAC – sacrum PIR – piriformis SN – sciatic nerve

(continued)

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Table 13.3 (continued) Patient position

Transducer position and description

Short axis to hamstring tendon origin at ischial tuberosity, short axis to femur

Long axis to hamstring tendon, long axis to femur

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Picture of scan and labeled structures

Pearls/pitfalls In assessing the hamstring tendon origin, be careful of anisotropy Note that the semimembranosus tendon, which begins laterally, will move deep and medial to the conjoint tendon

Labeled structures ISCH – ischium H T – hamstring tendon

Labeled structures ISCH – ischium H T – hamstring tendon

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pendicularly, but it is the one most likely to encounter the lateral femoral circumflex artery. The examiner usually can inject into the joint capsule overlying the femoral neck, avoiding the artery.

Is Impingement or Labrum the Pain Generator? An injection into the femoroacetabular joint space can be diagnostic if you are unclear of the pain generator. Initially, if the patient is pain-free after a joint injection, the cause of the pain is likely from within the joint (osteoarthritis, impingement/labrum). If there is no improvement, then the likely cause of pain is not intra-articular. Pain may be from the iliopsoas tendon or bursa and can be confirmed with a diagnostic injection with lidocaine.

Is Trochanteric Bursitis the Source of Pain? Structural causes of lateral hip pain include the gluteus medius bursa, the trochanteric (subgluteus maximus) bursa, and insertional tendon tear or tendinopathy. If you see fluid in the trochanteric bursa, do not assume that it is the only area of inflammation. The gluteus medius tendon and bursa should concurrently be evaluated, and referred pain sources, such as the lumbar spine, need to be considered.

Where Is the Pain from Piriformis Syndrome? The pain is most commonly felt in the buttocks and described as sciatica, but the more common site of injury is near its insertion on the superior femur. The patient may experience neuropathic symptoms anywhere along the distribution of the sciatic nerve if it is irritated. If the piriformis tendon is hypoechoic and stands out from the other tendons inserting on the greater trochanter, then this is likely where the injury is located, and the treatment should be focused here.

Red Flags If there are concerns for infection of the hip (i.e., warmth of the joint, fever, acute onset), ultrasound is unable to differentiate infection vs. effusion of the hip joint. However, a sample of the joint fluid can be obtained for analysis to assist in obtaining the diagnosis. An injection should not be attempted if there is any possibility of vascular structures in the planned pathway to the joint.

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Pearls and Pitfalls Pearls • Visualize the contralateral joint to confirm abnormal findings on affected side. • The rectus femoris lies superficial to the iliopsoas. The iliopsoas lies superficial to the joint capsule. • The iliopsoas bursa is superficial to the joint capsule, but is normally not seen unless an effusion is present. The presence of effusion should be confirmed in both short and long axis. • For a hip joint injection, the examiner usually can inject into the joint capsule overlying the femoral neck. • Using a 35 mm or 3.5 cm, 22-gauge spinal needle allows for adequate depth penetration to the hip joint for most injections. Pitfall • If injecting from a superior approach, choosing an approach in which the femoral head is more convex will make approach to the capsule more difficult.

Clinical Exercise/Homework 1. Record a picture of the anterior view of the hip joint in the oblique longitudinal plane parallel to the femoral neck. Identify the acetabulum and joint capsule. Record a picture of the iliopsoas tendon in transverse view superficial to the hip joint. Record pictures of the femoral and circumflex vessels using the Doppler setting. 2. Record a picture of the lateral view of the hip in short axis (transverse) position. Identify the potential space of the greater trochanteric bursa and the insertion of the gluteus medius and the piriformis tendons.

Suggested Reading Bianchi S, Martinoli C.  Ultrasound of the musculoskeletal system. New York, NY: Springer; 2007. European Society of Musculoskeletal Radiology. “European Society of Musculoskeletal Radiology Guidelines.” Essr.org. ESSR European Society of Musculoskeletal Radiology. n.d. Web. May 2019. Jacobson JA.  Fundamentals of musculoskeletal ultrasound. third ed. Philadelphia, PA: Saunders Elsevier; 2017. Malanga G, Mautner E. Atlas of Ultrasound-Guided Musculoskeletal Injections. McGraw-Hill Education: New York, NY; 2014. McNally E. Practical musculoskeletal ultrasound. second ed. Oxford: Churchill Livingstone; 2014. Stoller DW.  Stoller’s atlas of orthopaedics and sports medicine. Baltimore, MD: Lippincott Williams & Wilkins; 2008.

14

Groin Christine Eng and Steven A. Makovitch

Approach to the Patient Patients with groin pain should always be evaluated for hip pathology. Please refer to Chap. 13 for evaluation of the hip. Evaluation of the groin can be challenging given the complex anatomy, patient positioning, and varying depths of tissue to be evaluated. The evaluation techniques described in this chapter will require the patient to perform a number of dynamic maneuvers while the probe is placed on various areas of the patient’s groin. A professional, yet comforting, environment and respect for the patient’s privacy are necessary to obtain optimal scans. The patient should be interviewed fully clothed first, then asked to change into a gown or shorts. A sheet or towel should also be applied to the groin region. The procedure should be described to the patient, and an assistant or chaperone should be present during the examination.

Equipment Transducer selection may vary with the habitus of the patient and structure being evaluated. In general, it is best to select the transducer with the highest resolution in

which you can adequately view the structures given the variability of patient body habitus. For example, the evaluation of groin musculature in a thin individual may be best with a linear transducer around 10–12  MHz, while in a larger individual may require a curvilinear with less than 10 MHz.

Evaluation of the Groin The patient is placed in a supine position with knees flexed and asked to relax their hips to achieve a slightly abducted and externally rotated position. In this position, it is easy to find the first anatomic landmark: the pubic symphysis. A transverse or short-axis view is obtained to evaluate the joint for bony cortical irregularity, asymmetry, synovial hypertrophy, and presence of fluid. These findings can often be seen in the asymptomatic population. However, if the patient’s typical pain is reproduced with sono-palpation this may indicate pathology. From the home base at the pubic tubercle, the rectus abdominis is first viewed at the insertion to the pubis as the probe moves superiorly. Rotate the probe 90° to also obtain long-axis views of these tendons (see Table 14.1).

C. Eng Harvard Medical School, Spaulding Rehabilitation Hospital, Department of Physical Medicine and Rehabilitation, Charlestown, MA, USA S. A. Makovitch (*) Harvard Medical School, Spaulding Rehabilitation Hospital, Department of Physical Medicine and Rehabilitation, Charlestown, MA, USA VA Boston Healthcare System, Boston, MA, USA e-mail: [email protected] © Springer Nature Switzerland AG 2021 J. M. Daniels, W. W. Dexter (eds.), Basics of Musculoskeletal Ultrasound, https://doi.org/10.1007/978-3-030-73906-5_14

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192 Table 14.1  Evaluation of the pubic symphysis and rectus abdominis Patient position The patient is supine (face up). Have patient flex knees about 45–60°, then abduct hips

C. Eng and S. A. Makovitch

Transducer position and description

Transverse or short-axis view Probe is placed on pubic symphysis in transverse position

Longitudinal or long-axis view Probe is place with caudal end at the pubic tubercle on either side of the pubic symphysis.

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Picture of scan and labeled structures

Pearls/pitfalls Strongly consider an assistant or chaperone to help with the scan. (At some institutions, this is required.) Evaluate the pubic symphysis for bone irregularity and effusion Dynamic testing maneuvers: Sono-palpation; You can have patient straighten knees and do alternate leg lifts; evaluate for joint movement and pain Anatomic variation may exist in this location with variable appearance of the pyramidalis muscle shown in the images below

Labeled structures PS—Symphysis pubis with overlying superior pubic ligament PT—Pubic tubercle RA—Rectus abdominis

Labeled structures PS—Symphysis pubis PT—Pubic tubercle RA—Rectus abdominis P—Pyramidalis

Labeled structures for rectus-­adductor aponeurosis PT—Pubic tubercle RA—Rectus abdominis aponeurosis AD—adductor

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C. Eng and S. A. Makovitch Superficial inguinal ring

Conjoint tendon

Rectus abdominis

Inguinal ligament

12 9

3 6

Pubic symphysis

Pubic tubercle

Adductor longus

Fig. 14.1  Pubic clock schematic for assessment of the groin. (From Falvey et al. (2016) [1]).

The probe may now be directed so it is centered on the pubic tubercle in a short-axis position. The center of the probe should rest on “the home base of the pubic tubercle” which acts as the center of a clock face and each side of the probe acts like one of the hands of a clock. The “hands” of the clock should be pointing toward 9 o’clock and 3 o’clock positions (see Fig. 14.1). Now move the probe inferolaterally (6–7 o’clock position) to the adductor tendon which originates along the superior body of the pubis to the inferior pubic ramus. Evaluate for tears and/or signs of tendinopathy. There are three muscle-tendon layers inserting here from the most superficial to the deepest: the adductor longus, adductor brevis, and adductor magnus. Visualize the tendons in the long-axis view at the origin and then rotate the probe 90° for a short-axis view. Follow the tendons distally until the muscles are visualized in both the long- and short-axis. Either increasing depth or changing to a curvilinear transducer may be required to fully visualize the musculature distally. The gracilis muscle can also be evaluated by sliding the probe medially from the adductor origins using a similar approach. For all structures, scanning may be performed bilaterally for side-to-side comparison [1] (see Table 14.2). Next, we move to the evaluation of the superficial anterior hip and groin musculature (Fig. 14.2). Now place the probe in a similar manner as before with the transducer

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over the bony anatomic landmark of the ASIS (anterior superior iliac spine) where the more lateral tensor fascia latae and more medial sartorius muscles originate. Just inferior to this lies the AIIS (anterior inferior iliac spine) which is the origin of the rectus femoris. This region is especially important to evaluate in the adolescent athlete as this is a common site of injury. Reproduction of pain by sono-palpation and/or dynamic activation helps confirm these tendons are true pain generators as tendinopathy may exist in asymptotic individuals (Table 14.3).

Common Problems Snapping Hip Syndrome (Table 14.4) Patients may present with a painful “snapping” of the hip or coxa saltans. Intra-articular causes of hip snapping may result from acetabulum impingement or labral pathology which may be reviewed in the dedicated hip chapter. Two more common extra-articular causes include the internal snapping hip of the iliopsoas tendon at the anterior hip and the external snapping hip of the iliotibial band at the lateral hip.

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Although internal snapping hip is traditionally ascribed to the iliopsoas moving over the iliopectineal eminence or the femoral head as it traverses the hip joint, there are several more frequently visualized mechanisms for snapping. This may include the psoas tendon flipping around the muscular iliacus, bifid psoas major tendons flipping, the psoas tendon moving over the AIIS, or after hip arthroplasty the iliopsoas flipping over a protruding acetabular component. Evaluate the anterior hip in a sagittal oblique plane to identify the femoral head and acetabulum. The transducer is then turned transversely to identify the iliopsoas at the acetabular rim. Dynamic evaluation is an advanced technique and it is helpful to have an assistant. Move the hip from a flexed, abducted, and externally rotated position to an extended, adducted, and internally rotated position while keeping the tendon in view. Visualize for motion or tendon displacement corresponding with the snapping [2–5]. External snapping hip occurs in the lateral hip and most commonly refers to the anterior portion of the iliotibial band (ITB) subluxating over the lateral facet of the greater trochanter. The IT band may be visualized moving anteriorly over the greater trochanter during hip flexion and posteriorly during extension. The ITB may be evaluated in long-axis at the level of the greater trochanter with the patient side-lying

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Table 14.2  Evaluation of the adductors Patient position The patient is supine (face up). Have patient flex knees about 45–60°, then abduct hips

Transducer position and description

Long-axis view Slide probe laterally over pubic ramus in long axis to adductors

Short-axis view Rotate the probe 90° for a short-axis view. Follow the tendons distally until the muscles are visualized in both long and short-axis

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Picture of scan and labeled structures

Adductor attachment to pubic ramus Labeled structures P—Pubis AL—Adductor longus AB—Adductor brevis AM—Adductor magnus

Short-axis view of adductor muscles Labeled structures AL—Adductor longus AB—Adductor brevis AM—Adductor magnus

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Pearls/pitfalls Depending on body habitus, either increasing depth or a curvilinear transducer may be required to fully visualize the musculature distally Full tendon visualization with reduction of anisotropy may be improved with more thigh abduction angle at the origin For male patients, the testes may be wrapped in a towel or sheet and held by the patient away from scanning site

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ASIS AIIS

s

TFL

IlioP

RA

External oblique aponeurosis

Superficial inguinal ring

Pec AL

Pubic tubercle

AL

r. Sa

Gr

RF VL

VM

Fig. 14.2  Anterior hip musculature. (From Falvey et al. (2016) [1])

with the affected side up. Note any ITB thickening or presence of hypoechoic fluid which may underly the ITB.  To evaluate for snapping, place the probe over the greater trochanter in short-axis to the femur. Then have the patient flex and extend the hip while keeping the trochanter in view in an attempt to visualize the ITB flipping over the greater trochanter.

Evaluation of Hernias Dynamic ultrasound is helpful for the diagnosis of inguinal hernias, which should always be considered as a potential cause of groin pain [6]. The four primary types of inguinal hernias include indirect, direct, femoral, and Spigelian hernias (Fig.  14.3). Three essential soft-tissue landmarks for orientation include the lateral margin of the rectus abdominis, the inferior epigastric artery (IEA), and the inguinal ligament. These three boundaries outline an anatomic area known as Hesselbach’s triangle where direct hernias occur. In contrast, indirect hernias occur lateral to the IEA and follow the spermatic cord through the deep inguinal ring. Femoral hernias occur distal to the inguinal ligament and medial to the femoral vasculature through the femoral canal. Lastly, Spigelian hernias are rare and occur due to defect in the transverse abdominis aponeurosis at the lateral margin of the rectus abdominis muscle, superior to the IEA [7, 8]. Place the patient in a supine position with hips mildly flexed and externally rotated for comfort. Systematic evaluation starts superiorly looking for Spigelian hernia at the

14 Groin

level of the umbilicus in a transverse view over the lateral margin of the rectus abdominus. As the transducer is moved inferiorly, the IEA can be identified as it passes laterally in an oblique orientation and deep to the rectus abdominus. Spigelian hernia occurs superior to this vessel. Next, follow the IEA inferolaterally in a more oblique orientation until it meets the superior aspect of the inguinal canal or the deep inguinal ring which will be cranial to the inguinal ligament. Identify the spermatic cord in males which has a heterogeneous vascular structure unlike the inguinal ligament which will have the typical fibrillar pattern. At this location lateral to the IEA, assess for indirect hernia of the intra-abdominal contents through the deep inguinal ring and inguinal canal in both short and long-axis. An alternate method is to place one gloved finger in the inguinal canal into the external superficial ring just as one checks for an indirect hernia clinically. The probe in the other hand can then follow the canal up to the deep internal ring to perform the evaluation. For evaluation of a direct hernia, move the probe medially to Hesselbach’s triangle in the same orientation. A hernia will be visualized medially to the IEA with Valsalva. Lastly, to visualize femoral hernia move the transducer inferiorly following the femoral vessels inferior to the ingui-

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nal ligament. Identify the femoral nerve, located laterally to these vessels. (The mnemonic NAVEL is useful to remember—nerve, artery, vein, empty, lymphatics.) Ask the patient to perform a Valsalva maneuver. Femoral hernia will be observed medial to the femoral vein (into the “empty” space in NAVEL) see Table 14.5.

Sports-Related Groin Pain Sports-related groin pain is a complex diagnostic problem with multiple names, but most commonly referred to as sports hernia or athletic pubalgia. The term hernia may be misleading as no true hernia exists. Instead, the groin pain may stem from a weakness, diastasis, or disruption of the tranversalis fascia at the rectus abdominis border or close to the external ring of a true direct hernia. On dynamic ultrasound, this may be visualized by having the patient perform Valsalva or strain maneuvers and looking for fat protrusion medial to the lower epigastric vessels. Place the ultrasound probe at the lateral portion of the rectus abdominis in long-­ axis and identify the inferior epigastric artery. Then, move the probe inferiorly until the artery is about 1 cm away from the muscle. Note any bulging of the abdominal wall during Valsalva. Note that this is the positioning for evaluation of

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200 Table 14.3  Evaluation of superficial anterior hip and groin musculature Patient position Patient supine With hip and knees extended, hip in slight external rotation

Transducer position and description

longitudinal or long-axis view The probe is placed long axis, on the iliac crest

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Picture of scan and labeled structures

Labeled structures ASIS—Anterior superior iliac spine AIIS—Anterior inferior iliac spine RF—Rectus femoris SA—Sartorius

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Pearls/pitfalls Palpation of iliac crest and anterior aspect allows for identification of ASIS and AIIS bony landmarks For sartorius activation have the hip abducted with hip and knee flexed. Then have the patient adduct the hip against resistance. For the rectus femoris have the patient perform resisted straight leg raise

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Table 14.4  Evaluation of patient for snapping hip syndrome (A) Internal Snapping hip (B) External Snapping hip Patient position A Patient supine. Move the hip from a flexed, abducted, and externally rotated position to an extended, adducted and internally rotated position while keeping the tendon in view.

Transducer position and description

Sagittal oblique plane: Identify the femoral head and acetabulum Then flip to transverse to identify the iliopsoas at the acetabular rim

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Picture of scan and labeled structures

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Pearls/pitfalls Try to reduce downward probe pressure as it is possible to tether structures and miss snapping. Also patients may have varying provoking movements which also should be evaluated In adolescents, sono-palpation of these areas may reproduce pain if patient has apophysitis

Iliopsoas long-axis

Iliopsoas short-axis Labeled structures IP—Iliopsoas A—Acetabulum L—Labrum FH—Femoral head NAV—Femoral nerve, artery, and veins

(continued)

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Table 14.4 (continued) Patient position B Patient side-lying with the affected side up. Have the patient flex and extend the hip or perform motion that reproduces the symptomatic snapping

Transducer position and description

Long-axis view Probe placed over greater trochanter of femur with the ITB visualized longitudinally in the plane of the femur

Short-axis view Probe placed at the greater trochanter to look for dynamic subluxation of the ITB

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Picture of scan and labeled structures

Labeled structures ITB—Iliotibial band GT—Greater trochanter

Pearls/pitfalls

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neurosis injury, and pubic-related groin pain at the pubic symphysis. Ultrasound may help in distinguishing some appropriate pain generators with sono-palpation or dynamic maneuvers which reproduce the pain.

The Postoperative Hip

Fig. 14.3  A diagram, showing the typical locations of different types of groin hernia and its relationship to the adjacent structure. (a) Spigelian hernia, (b) Indirect inguinal hernia, (c) Direct inguinal hernia, and (d) Femoral hernia. (Adapted from Lee et al. (2013) [8])

direct inguinal hernia, but the transversalis fascia should remain intact [9]. Athletic groin pain also encompasses various pathologies at the confluence of structures with opposing biomechanical forces including the rectus abdominis insertion and aponeurosis, adductor tendon origin, inguinal ligament, and the pubis. It historically has been a “waste basket” diagnosis that includes adductor tendinopathy and partial tears, rectus apo-

Outcomes are generally favorable after hip arthroplasty, but in the small percentage of patients who continue to have pain plain radiographs are recommended in addition to the ultrasound examination. Patient complaints of postoperative hip pain can be divided into intra-articular versus extra-articular causes. Intra-articular complications may include loosening, instability, infection, fracture, metallosis, and dislocation. Extra-articular causes commonly include iliopsoas impingement, lateral hip pain from gluteal tendinopathy or bursitis, referred pain from the lumbar spine, or sciatic or gluteal nerve irritation. If there is excessive acetabular cup retroversion after arthroplasty, there may be an anterior overhang which may lead to impingement against the deep aspect of the iliopsoas tendon. Ultrasound is a favorable modality for this assessment as there is limited metal artifact, high spatial resolution of the soft tissues, and ability to assess dynamic function. If the patient has a complaint of pain over the anterior portion of the hip with resisted hip flexion, the iliopsoas and its relationship to the acetabular component should be evalu-

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ated. First assess the iliopsoas tendon in relation to the prosthesis in both short and long-axis. As the prosthesis moves anteriorly during hip flexion, it will occasionally create friction between the prosthesis (especially if it is oversized) and the tendon. Irregularity and fibrosis of the iliopsoas muscle or surrounding bursitis can be observed. Dynamic testing, such as having the patient flex and extend or internally or externally rotate the hip, accentuates this. A peritendinous injection of anesthetic with or without steroid in this location may be considered as a diagnostic test for iliopsoas impingement. Next, the joint should be evaluated for any obvious bony step-off, soft-tissue masses, excessive synovitis, or effusion (a small amount of either is normal). Doppler flow showing increased vascularity in these patients may signify synovitis. If the infection is suspected, aspiration of the effusion for testing is recommended. If a bony abnormality is noted additional imaging starting with radiographs is recommended.

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Clinical Experience 1. Perform a scan of the pubic symphysis and identify the insertion of the rectus abdominis and the origin of the adductors. Assess for abdominal and inguinal hernias using dynamic Valsalva maneuvers. Assess for causes of sports-related groin pain. 2. Identify, scan, and record the ASIS, the origin of the sartorius, AIIS, and the origin of the rectus femoris muscle. 3. Identify, scan, and record the iliopsoas muscle as it passes over the anterior aspect of the hip joint by having the patient flex and extend the hip; then, with the help of an assistant, internally and externally rotate the foot while scanning the iliopsoas. In both positions, observe for snapping or impingement.

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Table 14.5  Evaluation of hernias: (a) Spigelian, (b) Indirect inguinal hernia, (c) Direct inguinal hernia, (d) Femoral hernia A

Patient position Supine

Transducer position and description

Short-axis to lateral border of the rectus abdominis, move probe inferiorly until visualizing the inferior epigastric vessels Labeled structures RA—Rectus abdominis lateral border IEA—Inferior epigastric artery IL—Inguinal ligament B

Supine

Oblique axis to abdomen, longitudinal and superior to the inguinal ligament, following the inferior epigastric vessels Labeled structures RA—Rectus abdominis lateral border IEA—Inferior epigastric artery IL—Inguinal ligament

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Picture of scan and labeled structures

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Pearls/pitfalls Have the patient perform Valsalva to view the AC move through the transverse abdominis fascia defect lateral to the rectus muscle

Labeled structures RA—Rectus abdominis IEA—Inferior epigastric artery and vein (best visualized with doppler) AC—Intra-­abdominal contents EO—External oblique muscle IO—Internal oblique muscle TA—Transversus abdominis fascia (note the transversus abdominus muscle is out of view) Arrow—Location of a Spigelian hernia

Indirect hernias will be lateral to the IEA and may have a small neck

Labeled structures EIA—External iliac artery and vein IEA—Inferior epigastric vessels Arrow—Location of an indirect inguinal hernia through the deep inguinal ring

(continued)

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Table 14.5 (continued) C

Patient position Supine

Transducer position and description

Oblique axis to abdomen, longitudinal and superior to the inguinal ligament Move probe medially from point (b) Labeled structures RA—Rectus abdominis lateral border IEA—Inferior epigastric artery IL—Inguinal ligament D

Supine

Move the transducer inferiorly following the femoral vessels inferior to the inguinal ligament Labeled structures RA—Rectus abdominis lateral border IEA—Inferior epigastric artery IL—Inguinal ligament

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Picture of scan and labeled structures

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Pearls/pitfalls Direct hernias will be medial to the IEA and may have a larger neck

Labeled structures IEA—Inferior epigastric vessels (best visualized with doppler) Arrow—Location of a direct inguinal hernia medial to the IEA

Identify the femoral nerve, artery, and veins. Remember the external iliac vessels continue as the femoral vessels as they pass under the inguinal ligament Ask the patient to perform a Valsalva maneuver. Femoral hernia will be observed medial to the femoral vein (into the “empty” space in NAVEL)

Labeled structures N—Femoral nerve A—Femoral artery V—Femoral vein Arrow—Location of femoral hernia medial to the femoral vein

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References 1. Falvey ÉC, King E, Kinsella S, Franklyn-Miller A. Athletic groin pain (part 1): a prospective anatomical diagnosis of 382 patients— clinical findings, MRI findings and patient-reported outcome measures at baseline. Br J Sports Med. 2016;50(7):423–30. 2. Bureau NJ.  Sonographic evaluation of snapping hip syn drome. J Ultrasound Med Off J Am Instit Ultrasound Med. 2013;32(6):895–900. 3. Deslandes M, Guillin R, Cardinal E, Hobden R, Bureau NJ.  The snapping iliopsoas tendon: new mechanisms using dynamic sonography. AJR Am J Roentgenol. 2008;190(3):576–81. 4. Piechota M, Maczuch J, Skupiński J, Kukawska-Sysio K, Wawrzynek W. Internal snapping hip syndrome in dynamic ultrasonography. J Ultrason. 2016;16(66):296–303.

C. Eng and S. A. Makovitch 5. Yen Y-M, Lewis CL, Kim Y-J.  Understanding and treating the snapping hip. Sports Med Arthrosc Rev. 2015;23(4):194–9. 6. Robinson A, Light D, Nice C. Meta-analysis of sonography in the diagnosis of inguinal hernias. J Ultrasound Med Off J Am Instit Ultrasound Med. 2013;32(2):339–46. 7. Jamadar DA, Jacobson JA, Morag Y, Girish G, Ebrahim F, Gest T, et al. Sonography of inguinal region hernias. AJR Am J Roentgenol. 2006;187(1):185–90. 8. Lee RK, Cho CC, Tong CS, Ng AW, Liu EK, Griffith JF. Ultrasound of the abdominal wall and groin. Canadian Association of Radiologists Journal = Journal l'Association canadienne des radiologistes. 2013;64(4):295–305. 9. Boric I, Isaac A, Dalili D, Ouchinsky M, De Maeseneer M, Shahabpour M.  Imaging of articular and extra-articular sports injuries of the hip. Semin Musculoskelet Radiol. 2019;23(3):e17–36.

Ultrasound Guidance of Procedures

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Erik S. Adams

Introduction The use of ultrasound guidance (USG) for percutaneous procedures offers significant advantages over fluoroscopic guidance or landmark guidance (LMG). Compared to LMG, USG results in superior accuracy, and compared to fluoroscopic guidance, USG injections are safer. Unlike fluoroscopy, ultrasound delivers no ionizing radiation and provides soft tissue anatomic detail. With continuing improvement in ultrasound technology, tissue detail and needle conspicuity are enhanced, and deeper tissues are better visualized, allowing performance of injections and procedures that are deeper or are closer to sensitive structures. Improved sonographic detail also allows better visualization of pathology and therefore a better understanding of appropriate treatment options for the patient. Ultrasound guidance has a steep learning curve that should not be underestimated, and accuracy and safety are not automatically guaranteed by the use of an ultrasound machine. The beginner should seek out instruction utilizing cadavers and then begin in the living with injections that are considered low-risk. Development of and adherence to proper guidance technique are essential and should be considered a prerequisite to learning more difficult procedures. A safe and accurate procedure requires visualization of the tip of the needle or percutaneous instrument being used, as well as accurate guidance to the therapeutic target; indeed, if either of these is missing, the procedure cannot be considered to be ultrasound guided. A detailed three-dimensional understanding of anatomy is important when using ultrasound guidance. Knowledge of the sonographic appearance of injection targets and pathology is necessary for accuracy, and the ability to recognize and avoid sensitive structures is essential for safety. Lastly, the inclusion of an ultrasound transducer in a procedure E. S. Adams (*) Montana State University, Department of Mechanical and Industrial Engineering; Bozeman Sports Medicine, Bozeman, MT, USA e-mail: [email protected]

increases the demands on the clinician for maintaining sterility. Sterile ultrasound transducer covers are available, and their use requires some planning as to how the transducer cover will remain sterile throughout the procedure.

Accuracy of Ultrasound-Guided Versus Landmark-Guided Injections Studies comparing the accuracy of USG versus LMG injections show variable results, depending on the injection target. Table  15.1 summarizes some relevant studies of injection accuracy. In general, USG injections are more accurate than LMG, with most USG studies reaching or approaching 100% accuracy. Hashiuchi et  al. showed an accuracy of 87% for USG and 27% for LMG injections of the long-head biceps tendon sheath [3]. Accuracy for injection of the AC joint in three separate cadaver studies was 90–100% for USG and 40–72% for LMG [8, 13, 21], and Patel et al. showed 93% vs. 73% for USG and LMG accuracy, respectively, for cadaveric glenohumeral joints [22]. However, an SASD bursa injection study by Dogu et al. showed approximately equal accuracy for USG and LMG (65% vs 70%, respectively) [15]. Care is needed in interpreting these studies. One research group’s success or failure at ultrasound guidance may not mean that all clinicians will obtain the same result; indeed, there is considerable variability between studies. Although Dogu et al. [15] showed 65% accuracy with USG injections into the SASD bursa, Bhayana et al. [16] had an accuracy rate of 100%. The proper interpretation of discrepancies such as these may relate to issues of technique or experience, or perhaps the quality of the ultrasound equipment. It would seem that easily palpated joints should be easily injected with landmark guidance. However, physiatry residents in one study were able to accurately inject the acromioclavicular joint only 17% of the time [23], and more experienced physicians accurately injected hand MCP and PIP joints by landmark guidance 59% of the time [24]. Park

© Springer Nature Switzerland AG 2021 J. M. Daniels, W. W. Dexter (eds.), Basics of Musculoskeletal Ultrasound, https://doi.org/10.1007/978-3-030-73906-5_15

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Table 15.1  Summary of studies on the accuracy of guided vs. unguided or fluoroscopically guided injections References Muir JJ et al. [1], 2011 Rutten et al. [2], 2007 Hashiuchi et al. [3], 2011 Cunnington et al. [4], 2010

Target, patient type Peroneal tendon sheath, cadaver SASD bursa, live patients Long-head biceps tendon sheath, live patients Multiple large- to medium-sized joints, live patients Wrist, live patients

Method of confirmation Other Latex injection, dissection Gadolinium injection, MRI Contrast injection, CT Contrast injection, radiographs

US-guided injections performed by fellow, unguided by faculty “Wrist joint” – not further specified Comparison of more vs. less experienced injector

100% (10 of 10)

Unguided accuracy 60% (12 of 20), 4 intra-tendinous 100% (10 of 10)

87% (13 of 15)

27% (4 of 15)

83% (76 of 92)

66% (61 of 92)

27 of 30

27 of 30

100% for both more and less experienced (20 injections each)

100% (20 of 20) more experienced 55% (11 of 20) less experienced 25% combined TMT joints 1 and 2 (7 of 28)a 72% (31 of 43)

US-guided accuracy 100% (20 of 20)

Luz KR et al. [5] Curtiss et al. [6], Knee, cadaver 2011

Contrast

Khosla S et al. [7], 2009

Foot TMT joints, cadaver

Methylene blue injection, dissection

Sabeti-Aschraf M et al. [8], 2011 Finnoff JT et al. [9], 2010

Acromioclavicular joint, cadaver

Ultrasound exam

Pes anserinus bursa, cadaver

Latex injection, dissection

Unguided injection used ultrasound to mark location

92% (11 of 12)

Wisniewski SJ et al. [10], 2010 Wisniewski SJ et al. [10], 2010 Smith J et al. [11], 2015

Ankle anterior joint line, cadaver Ankle sinus tarsi, cadaver Posterior subtalar joint, cadaver

Long-axis approach

100% (20 of 20)

Short-axis approach

90% (18 of 20)

35% (7 of 20)

Reach JS et al. [12], 2009

Ankle and foot structures, cadaver

Latex injection, dissection Latex injection, dissection Tap water injection, sonographic detection of joint capsule distention Methylene blue, dissection

17% (2 of 12) – partially ultrasound guided 85% (17 of 20)

Peck E et al. [13], 2010 Aly et al. [14], 2015 Dogu et al. [15], 2012 Bhayana et al. [16], 2018 Hashiuchi et al. [3], 2011 Wu T et al. [17], 2016

ACJUS, cadaver

Petscavage-­ Thomas and Gustas [18] 2016

Latex injection, dissection

Fluoroscopic accuracy 64% combined TMT joints 1 and 2 (18 of 28) 89% combined TMT joints 1 and 2 Large volume injected, 95% (54 of 57) to aid detection

2 additional specimens 100% (10 of 10) CT of 2 add’l specimens injected with radiographic contrast; confirmed accuracy CT imaging 100% (10 of 10) for 1st and 2nd MTPJ, tibiotalar joint, FHL, and tibialis posterior tendon sheaths. 90% (9 of 10) for subtalar joint 100% (10 of 10)

Unguided injections not performed

Gadolinium, MRI

Double-blind RCT

65% (15 of 23)

70% (16 of 23)

USG: US image LMG: fluoroscopy Contrast CT

RCT. Assessor of accuracy blinded Single-blind RCT

100% (30 of 30)

93% (28 of 30)

87% (13 of 15)

27% (4 of 15)

7 RCT, 2 non-RCT

Risk ratio 1.21 favoring US-guided

Retrospective study

US-guided 91% (48/53) first pass, 98% 2nd pass

Latex injection, dissection

Unguided injections not performed

40% (4 of 10)

ACJ, meta-analysis SASD bursa, live patients Subacromial-subdeltoid bursa, live patients LHBT sheath

Fluid obtained Knee arthrocentesis meta-analysis, live patients LHBT sheath injection, Fluoro, ultrasound image live patients. USG vs. fluoro

Fluoro-guided 74% (37/50) first pass, 92% 2nd pass

15  Ultrasound Guidance of Procedures

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Table 15.1 (continued) References Scillia A et al. [19], 2015 De Luigi AJ et al. [20], 2019

Target, patient type AC joint, live patients SI joint

Method of confirmation Fluoro Contrast injection, fluoro

Other Palpation guided only

US-guided accuracy

The two failed injections had BMI >40

96% (48/50)

Unguided accuracy 37% (15/41) Unguided not performed

Ultrasound guidance technique unclear in this study

a

et al. showed an accuracy rate of 96% for USG and 61% for LMG for acromioclavicular (AC) joint injections [25]. Scillia et al. showed an accuracy of 37% for LMG injections of the AC joint [19]. USG injections of the long-head biceps tendon sheath were compared to fluoroscopic guidance in a 2016 study. Determinations of accuracy were divided into first-pass and final-pass attempts during the same injection. First-pass success was 91% for USG and 74% for fluoroscopic guidance, a difference that was statistically significant. There was no significant difference between guidance types for final-pass accuracy (98% and 92%, respectively) [18]. Not only is fluoroscopic guidance less accurate for this injection, it exposes the patient to ionizing radiation. One of the fluoroscopically guided subjects in this study had almost 4 minutes of fluoro time, owing to difficulty finding the target. Technique may play a role in the accuracy of USG injections. In a study of ultrasound-guided injections into the first and second tarsometatarsal joints [7], the combined accuracy for both joints was only 68%. However, the authors aligned the needle with the sagittal plane, rather than the coronal plane; the latter provides deeper access to the joint space and may therefore be preferred. The articular surfaces of all diarthrodial joints should be considered to be vulnerable to injury during injection, both by the needle and the high hydrostatic pressure of the injectate at the needle tip. A needle trajectory should therefore be chosen that does not allow the needle tip to rest on articular cartilage.

Safety and Patient Comfort Considerations Injection inaccuracy has a number of potential undesirable effects and complications. Aside from the lack of therapeutic benefit from a missed injection, the lack of response may convince the physician to look elsewhere for the pain generator, increasing costs, possibly subjecting the patient to unnecessary procedures, and prolonging the evaluation. Inaccuracy may also damage neighboring

structures. Table  15.2 provides some examples of structures at risk for selected injections. In some cases, inadvertent arterial puncture may be successfully treated with prolonged pressure to the bleeding artery, when there is unyielding tissue deep to the artery. Other arteries, such as the intercostals, those in the superior mediastinum, and the vertebral artery, do not have such an arrangement and may continue to bleed if punctured, despite pressure. Even with ultrasound guidance, consideration must be given to the consequences of arterial trauma for each anticipated injection and a needle trajectory chosen so as to minimize risk. Table 15.2  Structures vulnerable to needle trauma for selected injection targets Injection target Rhomboid major and minor, levator scapulae, upper trapezius (“trigger point” injections) Subclavian vein (e.g., intravenous line placement) Intercostal nerve Sternoclavicular joint Hip joint

Ankle talocrural joint Greater occipital nerve, near obliquus capitis inferior Lateral femoral cutaneous nerve Piriformis muscle belly Retrocalcaneal bursa, lateral approach Hamstrings origin Tarsal tunnel

Carpal tunnel

Neighboring sensitive structures Pleura, intercostal neurovascular bundle Pleura Pleura, intercostal artery Arteries and veins of the superior mediastinum [26] Lateral circumflex femoral artery and nerve, femoral vessels Deep and superficial fibular nerves, dorsalis pedis artery Vertebral artery within suboccipital triangle Peritoneum Peritoneum, superior gluteal artery and nerve Sural nerve Sciatic nerve, posterior femoral cutaneous nerve Tibial nerve and its branches, posterior tibial artery Median nerve, palmar branch of median nerve, ulnar artery

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Efficacy of Ultrasound-Guided Versus Landmark-Guided Injections

E. S. Adams

plantar foot, also benefit from the use of a nerve block. In tendons, sensory innervation is found in the paratenon, epitenon, and endotenon [30]. Tendons are innervated both by the nerve supplying the muscle connected to that tendon, as well as branches of afferent nerves supplying the overlying skin [31]. Since the metabolic functions within tendons, including cytokine release and cell proliferation, are in part neurally mediated [32], nerve blocks for short procedures should probably utilize short-acting anesthetics, so that neural function is only briefly interrupted. Considering that intra-tendinous injections often utilize biologics that must be distributed throughout a pathologic area, therefore requiring many passes of the needle, a nerve block may be needed in order to provide the desired level of anesthesia. When choosing the site of a block, it is important to remember that in some cases, the nerve supplying the tendon to be injected and its overlying skin are the same; in other cases they may differ. An example of the former would be the plantar foot (tibial nerve, or medial and lateral plantar nerves), and an example of the latter would be the dorsal foot (superficial fibular nerve for cutaneous, deep fibular nerve for tendons arising from muscles of the anterior compartment of the calf and intrinsic muscles of the dorsal foot). When such a distinction exists, two nerve blocks may be required, or one nerve block for the tendon and separate local anesthesia for the skin and fascia. In the lower extremities, motor nerve blocks impair the ability to walk, creating the possibility of injury. Patients should be closely supervised and assisted. Proper nerve block technique requires distribution of the anesthetic circumferentially around the nerve. Inadequate block may be due to an inadequate volume of anesthetic, insufficient time for it to take effect, failure to contact the nerve with the anesthetic, or iatrogenic bleeding that washes away the anesthetic. The deep surface of the nerve should be injected first, followed by the superficial surface. If the superficial surface of the nerve is injected first, any injected air may obscure the view of the nerve when attempting to subsequently inject deep to the nerve. Figure 15.1 shows an ultrasound image of a median nerve block proximal to the carpal tunnel.

Interpretation of efficacy studies is complicated by issues of accuracy but also the appropriateness of the injection or the injectate for the patient’s pathology. Cole et al. conducted a randomized, double-blind trial of USG vs. LMG injections into the SASD bursa for subacromial impingement syndrome, concluding that there was no difference in efficacy [27]. However, they did not compare the accuracy of each guidance method, and if their accuracy were equal, as with the study by Dogu et  al. [15] (65% for USG and 70% for LMG), a difference in clinical outcome should probably not be expected. Furthermore, of their 55 patients, 10 subsequently had surgery for conditions that included supraspinatus tears, a tumor in the humeral head, glenoid labrum tear, and snapping scapula. It could be argued that corticosteroid injection into the SASD bursa would not produce an improvement in any of these surgical conditions, so the accuracy of the injection becomes immaterial. However, when 184 patients with inflammatory arthritis were randomized to either USG or LMG corticosteroid injections, which could be argued as an appropriate therapy for this pathology, those injections that were accurate, whether USG or LMG, produced a better visual analog scale (VAS) pain response at 6 weeks than inaccurate injections. Interestingly, the USG group did not fare better than the LMG group, even though there was a statistically significant difference in accuracy between the two groups (83% vs. 66%, respectively, p = 0.01) [4]. The less than 100% accuracy rate for USG injections in this study might be explained by the fact that all USG injections were performed by rheumatology fellows; the LMG injections were performed by attending rheumatologists. A meta-analysis of 12 studies published between 2004 and 2012 did show a statistically significant improvement in VAS scores at 2 and 6  weeks postinjection for USG, compared to LMG [28]. Two studies of injection accuracy into the pes anserinus bursa address technique issues for ultrasound guidance. When USG was used to mark the position of the bursa on the skin and subsequently use only those marks for guidance, accuracy was 17% [9]. In a study by Lee et al., when real-­ time ultrasound guidance was used, accuracy was 100% [29]. The higher accuracy rate in this study was accompanied U  ltrasound Guidance: General Principles by a significantly improved VAS response at 1 and 4 weeks postinjection. Ultrasound-guided injections are more difficult than unguided injections, as the clinician must add the additional tasks of maintaining an adequate sonographic image of the Ultrasound-Guided Nerve Blocks injection target, keeping the needle in view, and steering the needle. Beginners should select injections that are typically Nerve blocks offer a level of patient comfort for intra-­ easier. Ultrasound guidance may also encourage a wide varitendinous injections that is difficult to achieve with local ety of deeper and more difficult injections that one would not anesthesia. Injections in some areas of the body, such as the attempt unguided, as many of these carry substantial risk for

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Ultrasound probe long-axis

Fig. 15.1  Transverse sonogram demonstrating an injection of lidocaine along the deep surface of the median nerve, for a procedure on the palm of the hand. Approaching the undersurface of the nerve, the needle bevel is turned upward, and for the superficial surface, it is turned downward, to avoid spearing the nerve with the point of the needle. Closed arrow: ulnar artery. Open arrows: median nerve

iatrogenic injury, such as perforation of large arteries, nerve trauma, and entry into the peritoneum or pleura. It should be stressed that an injection is only directly ultrasound guided if both the needle tip and the intended target are simultaneously in view. It is therefore possible to be using ultrasound during an injection but without true ultrasound guidance. Examples of this would include losing sight of the needle tip, having a poor or nonexistent image of the intended target, seeing the needle shaft but not the tip when viewing in-plane or when doing an out-of-plane injection, and letting the needle tip proceed past the plane of the ultrasound beam. When planning an ultrasound-guided injection, the intended needle tract should be examined for the presence of arteries and nerves, the former aided by the use of Doppler imaging. Most injection targets can be approached by more than one route. Planning the injection should constitute a substantial portion of the time spent on the procedure. It is helpful to mark the planned needle trajectory on the skin and then sonographically examine this route, prior to inserting a needle. If the needle tract passes close to an artery, the Doppler function should be used during needle advancement, until the needle tip passes the artery. It is also desirable, if possible, to choose a trajectory that includes a bony barrier deep to the target, to prevent needle penetration into underlying structures. For example, when injecting the psoas bursa, injecting at a point over the hip joint capsule carries a risk of entering the hip joint. The safest route is over the anterior acetabulum. Similarly, when injecting a costotransverse joint or the dorsal scapular nerve, staying over a rib prevents inadvertent needle entry into the pleura. Once the needle approach to the target is chosen, an optimized image of the intended target is obtained and maintained. The transducer is then used as a guide for placement of the needle. Figure  15.2 illustrates this concept. When

Skin entry point

Needle

Fig. 15.2  In-plane injection technique, centering the needle under the transducer. An optimized ultrasound image of the injection target is first obtained, taking into account a needle tract that avoids sensitive structures; then the transducer position is used as a guide for needle placement

injecting in-plane to the transducer, the centerline of the transducer defines a plane that extends down into the patient, and the needle is placed precisely along this plane. The clinician must therefore monitor both the ultrasound image and the midline axis of the transducer. Figure 15.3 demonstrates a colinear arrangement of the clinician, needle, transducer, and screen, which facilitates achieving accurate alignment. Accurately placing a needle with an out-of-plane technique presents a different set of challenges. Once the optimized ultrasound image of the target is obtained and the transducer is anchored to maintain that image, one has to construct a spatial correlation between the image on the screen and the position of the target under the transducer. Many transducers are marked at their center point, so it is best to center the intended target on the ultrasound screen and then use this center point mark as a guide for needle placement. One should plan to intercept the plane of the ultrasound beam directly superficial to the intended target

E. S. Adams

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3 2 1

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Do not advanced past the plane of the ultrasound beam

Needle is withdrawn to skin, re-directed, and advanced

Fig. 15.4  Out-of-plane injection technique – “walking the needle tip down” the plane of the ultrasound beam

Fig. 15.3  Colinear arrangement of clinician’s eyes, needle, transducer, and ultrasound screen. This prevents requiring the clinician to turn to the side to view the screen, which may influence the needle trajectory

Ultrasound beam

and then “walk” the needle down to the target. This is accomplished by withdrawing the needle and redirecting it at a steeper angle (Fig. 15.4). It is tempting to drive the needle deeper by pushing its tip past the plane of the ultrasound beam, but the needle tip is then entering unvisualized tissue, so the injection has become unguided at this point. When the needle tip reaches the plane of the ultrasound beam, it appears as a dot on the image, and it should not be advanced any further, unless the transducer is moved farther from the needle entry point (Fig. 15.5). Finally, one can use an oblique approach, which is sometimes helpful for avoiding arteries and nerves, and this is performed much as one does a short-axis technique. Whichever technique is chosen, the needle is initially inserted bevel up, which aids visualization of the needle tip with the ultrasound. Typically, one advances the needle while injecting lidocaine, and then once in place, the syringe is changed, and the

Short axis probe orientation

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Skin The needle may only be advanced past pont A if the ultrasound probe is moved

After moving the probe, pont B becomes the new limit for the needle tip

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Fig. 15.5  Out-of-plane injection technique – moving the transducer to visualize the needle tip at a greater depth. This is useful when the injection target lies under the transducer position B in the illustration. The transducer at position A visualizes the needle first, and trajectory adjustments can be made at this point; then the transducer is moved to position B, and the needle is advanced further

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desired therapeutic agent is injected. It is important not to move the needle while changing syringes. If a sterile ultrasound transducer cover is being used, the transducer is laid onto the sterile field during this maneuver or held by its cord by an assistant.

Hydrodissection

Needle Steering Techniques The orientation of the needle bevel can be used to direct the needle. During advancement of the needle, the bevel acts as an inclined plane (Fig. 15.6). Additionally, the skin can be used as a fulcrum to steer the needle. Usually, both techniques are used simultaneously. If it is desired that the needle tip be brought more superficially, the bevel is placed down, and the needle is pressed into the skin to create an arc shape, which forces the needle tip more superficially. The opposite technique is used to deepen the needle tract (Fig. 15.7). This technique is useful for small adjustments in depth and can also be used to deviate left or right by turning the bevel sideways. When large adjustments are needed, it is best to withdraw the needle tip to the subcutaneous tissue and change the angle of entry.

Sterile Technique All injections should be done with aseptic technique, utilizing skin preparation with an antibacterial solution. Syringes on the field should only be handled with sterile gloves and not pre-filled by an assistant in a non-sterile manner. If the transducer is going to be close to the needle entry site, a sterile transducer cover should be used. Sterile ultrasound gel should also be used when the transducer is close to the nee-

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Inc

line of d pla be vel ne

dle entry site. If a sterile transducer cover is not used, the hand holding the transducer is no longer sterile, which must be kept in mind. Breaches of sterile technique are common when learning ultrasound guidance.

Advancing needle produces downwards force on bevel

Fig. 15.6  When advancing the needle, its bevel acts as an inclined plane, pushing the needle tip in the direction indicated

Fluid injection can be used to separate tissue planes or to create a space for injection of a therapeutic agent, a technique known as hydrodissection. Applications include structures that are pathologically adherent to one another, such as the median nerve and the transverse carpal ligament, and expanding a potential space for the injection of a therapeutic agent, such as between a tendon and its sheath. Upon reaching the space to be injected, the needle bevel is turned to face the nerve, tendon, or other structure being hydrodissected. As the space is expanded with injectate, the needle is advanced into the newly created space to extend the hydrodissection farther (Fig. 15.8). Nerve hydrodissection offers the opportunity to relieve peripheral nerve entrapment percutaneously. The technique involves expanding the tissue circumferentially around the nerve at the site of the entrapment. Since most nerves are accompanied by arteries, there is a potential not only for iatrogenic nerve injury but also for arterial injury. At the very least, arterial injury will result in bleeding, which produces inflammation and fibrosis, perhaps resulting in re-­entrapment of the nerve. Nerves that do not have a bony barrier along the deep surface may be insufficiently compressible with pressure to stop the bleeding. The sonographic visualization of the nerve can be short or long axis, and with a long-axis view of the nerve and an in-plane needle approach, hydrodissection can be extended along a length of the nerve. For entrapments that are difficult to hydrodissect, one may start with the needle trajectory short axis to the nerve (Fig. 15.1); then once the nerve is circumferentially surrounded with injectate, change to long axis and a new needle entry point; then extend the length of the bolus of fluid. The nerve should be contacted with the flat side of the needle bevel, to avoid spearing the nerve with the needle tip. Sterile saline, dilute lidocaine, and 5% dextrose are suitable options as an injectate.

Patient Positioning Minute changes in the position of the needle tip can compromise the success of an USG injection. For this reason, the patient needs to be well stabilized. A seated position, for example, is only used if one is injecting the elbow, wrist, or hand, and the extremity is supported on a surface. It does not

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Fig. 15.7  Technique for steering the needle, using the skin entry point as a fulcrum and orienting the needle bevel appropriately

Bending force on needle using skin as fulcrum

Syringe

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p lu Combination of needle bending and eve tip b ith e on bevel orientation steers neede tip deeper w le forc ed ne ard g in nw nc dow va Ad xer ts Needle steering best accomplished with 22 gauge needle size e

the transducer (Fig.  15.9a). Upon reaching the bursa, the bevel is turned downward, to avoid penetrating the paratenon with the needle tip. The expansion of the bursa has a distinct appearance, which serves as confirmation of correct placement (Fig.  15.9b). For difficult cases, such as an obese patient or a thickened peri-bursal fat layer, which makes the needle less visible, it may be helpful to turn the transducer into the sagittal plane, once the needle is in place, to visualize the needle tip out of plane. The expansion of the bursa in the anterior-­posterior direction may be better appreciated with this view. Slightly wiggling the needle can help with visualization of its tip. Fig. 15.8  Hydrodissection of the ulnar nerve. Long-axis sonogram of the ulnar nerve depicting a hydrodissection that is begun distal to and is then extended through the site of entrapment. Note that the needle bevel is turned downward, to avoid spearing the nerve with the needle tip. Asterisks: ulnar nerve, viewed long axis

work well for a shoulder injection, as any swaying of the patient, however minimal, may create difficulty with needle accuracy.

Injections by Joint Shoulder  ubacromial-Subdeltoid (SASD) Bursa (Fig. 15.9) S Successfully completed, this injection will result in the symmetrical expansion of the SASD bursa, which extends from the subacromial space to the deltoid insertion within the coronal plane, and from the infraspinatus to the rotator interval in the sagittal plane. Inaccurate placement may be indicated by the presence of a localized ellipsoid expansion of fluid during the injection. The patient is placed in the lateral decubitus position, a pillow under the arm to relax the bursa. The transducer is placed longitudinally along the supraspinatus, keeping the lateral acromion in view. The needle approach is in-plane to

 cromioclavicular (AC) Joint (Fig. 15.10) A This injection can be performed with the patient in a supine position with an anterior approach, or lateral decubitus position with an anterior or posterior approach. Figure  15.10a demonstrates an anterior approach with the patient in a lateral decubitus position. A lateral approach in the coronal plane is less desirable, as the needle tip will be directed at the articular cartilage of the distal clavicle and can cause iatrogenic injury. The available depth of the joint for the needle from this angle is also less than for an anterior or posterior approach. Note is made of the depth of the joint beneath the skin on the ultrasound image. The approach is out-of-plane to the transducer, and the needle should be placed in the middle of the “V” of the joint. Once the needle is centered in the joint, the transducer can be rotated into the sagittal plane to observe the needle in-plane to control its depth and to observe the expansion of the joint capsule during the injection (Fig. 15.10b).  lenohumeral (GH) Joint (Fig. 15.11) G This is the most difficult of the shoulder injections, as the needle trajectory is steep, the target is deep, and one must avoid penetrating the glenoid labrum. Of all guidance methods, only USG can ensure avoidance of the labrum, with proper technique. The patient is placed in the lateral decubitus position, with the side being injected located upward. The clinician stands at the patient’s anterior aspect, and the

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b

Fig. 15.9  Injection of the subacromial-subdeltoid (SASD) bursa. (a) Photograph showing patient and transducer positioning and needle approach angle. (b) Coronal oblique ultrasound image depicting injection of volume in the SASD bursa. Arrow, acromion; asterisks, injected volume

a

b

Fig. 15.10 Injection of the acromioclavicular (AC) joint. (a) Photograph showing the patient in a lateral decubitus position, transducer in the coronal plane, approaching from the anterior direction. (b)

Sagittal plane ultrasound image depicting the needle viewed out-of-­ plane within the “V” of the joint space. Asterisks: joint capsule

patient slides on the exam table toward the clinician, to the edge of the table. This gives the clinician access to the posterior aspect of the shoulder (Fig.  15.11a). A curved low-­ frequency transducer is preferred, as needle conspicuity is better with this transducer type when the needle angle is steep. The transducer is placed in the axial plane at the ­posterior GH joint line, demonstrating the posterior humeral head and posterior labrum. The needle is inserted in-plane to the transducer, at an angle that is tangential to the humeral head (Fig. 15.11b). Upon passing through the joint capsule and reaching the space between the articular cartilage of the humeral head and labrum, the bevel is turned toward the humeral head, and while injecting lidocaine or saline, it is slid into the joint space (Fig. 15.11c). Injecting fluid during needle advancement may “float” the labrum slightly, lifting it out of the way. The GH joint capsule is immediately adjacent to the labrum, so injected material will float the labrum only after penetrating the capsule.

 uprascapular Nerve Block (Fig. 15.12) S This nerve block may be useful for adhesive capsulitis of the shoulder, fenestration of or injection of biologic agents into the supraspinatus tendon, or as a diagnostic maneuver for suspected suprascapular nerve entrapment. Any injections in this area require awareness of the proximity of the cupola of the pleura, anterior to the superior margin of the scapula. The injection method described here utilizes the bony cortex of the supraspinous fossa as a backstop and therefore affords a greater degree of safety than an injection performed along the nerve proximal to the suprascapular notch, where it resides adjacent to the inferior belly of the omohyoid muscle. The suprascapular nerve is visualized in the suprascapular notch by first imaging the floor of the supraspinous fossa with the transducer in the plane of the scapula (coronal oblique) and then simultaneously anteriorly translating and toggling the transducer to visualize the suprascapular notch and its overlying superior transverse scapular ligament

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Fig. 15.11  Injection of the glenohumeral joint. (a) Illustration of the optimal needle angle with respect to the curvature of the posterior humeral head. The needle is tangential to the curvature of the humeral head. (b) Patient and transducer positioning illustrated for an injection at the posterior glenohumeral joint. Note the needle entry point close to the transducer and the steep angle of the needle. A sterile transducer

a

Fig. 15.12  Blockade of the suprascapular nerve at the suprascapular notch. (a) Patient and transducer positioning. The transducer is rotated into the coronal oblique plane, parallel to the long axis of the suprascapular fossa. (b) Coronal oblique sonogram of the suprascapular

cover is required (not shown). (c) Axial plane sonogram of the posterior GH joint, showing the steep needle trajectory, tangential to the humeral head, passing between the posterior labrum and articular cartilage of the humeral head. Closed arrow, articular cartilage of humeral head; open arrow, posterior labrum; line, desired needle trajectory

b

notch and adjacent suprascapular artery. Closed arrow, suprascapular artery, showing Doppler signal; open arrow, marker placed to demonstrate desired injection location in the suprascapular notch

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(Fig.  15.12a). It is helpful to visualize this on a skeletal model. The notch has a variable shape but become apparent as a gap in the cortex of the supraspinous fossa. Doppler imaging may disclose the suprascapular artery passing superficial to the superior transverse scapular ligament (Fig.  15.12b). The needle trajectory can be out-of-plane, entering the skin dorsal to the transducer. Special attention should be paid to the avoidance of puncturing the suprascapular artery and to the control of needle depth. As with all out-of-plane injections, the needle tip must not be advanced past the plane of the ultrasound beam. Localization of branches of the accessory nerve on the deep surface of the upper trapezius should be conducted before choosing a needle insertion point. Pearls and Pitfalls: Shoulder Injections • The needle entry point for a GH joint injection is immediately adjacent to the transducer, so a sterile transducer cover is required. • Chronic disease of the subacromial space may result in an adherent SASD bursa that needs to be opened with hydrodissection to accept the injectate. • Anterior to the suprascapular notch lies the cupola of the pleura, which can be punctured by advancing a needle past the suprascapular notch during suprascapular nerve block.

a

Fig. 15.13  Injection at the lateral epicondyle of the humerus. This approach is suitable for injecting either the common extensor tendon origin or the radial collateral ligament. (a) Patient and transducer positioning. The patient is seated alongside the exam table, elbow flexed to

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Elbow  edial or Lateral Epicondyle (Fig. 15.13) M With the use of ultrasound, it becomes apparent that many patients formerly diagnosed with epicondylitis have tears of the common flexor or extensor tendons at the medial or lateral epicondyles, respectively. At the lateral epicondyle, there may also be tears of the radial collateral ligament (RCL) complex and, at the medial epicondyle, the ulnar collateral ligament. Figure  15.13b depicts a sonogram of an injection at the origin of the RCL. Tears of the RCL complex should be evaluated for posterolateral rotatory instability. The injection is accomplished by laying the transducer longitudinally along the tendon, and the approach is from the distal aspect, in-plane to the transducer (Fig.  15.13a). The interior surface of the tear is repeatedly fenestrated, as is any bone from which the tendon has separated. Fenestration of the bone dulls the needle tip and should therefore be conducted with a separate needle. Cubital Tunnel (Fig. 15.14) Entrapment of the ulnar nerve can occur within the cubital tunnel, or more distally between the two heads of the flexor carpi ulnaris (FCU), deep to Osborne’s fascia. Proximal to the cubital tunnel, the arcade of Struthers is another possible entrapment location. A longitudinal sonographic view of the entrapped nerve may show an hourglass configuration to the nerve, and proximal to the entrapment, the cross-sectional area of the nerve will be increased. Hydrodissecting the nerve with saline or dilute lidocaine from surrounding tissue

b

90° with forearm resting on the table. (b) Longitudinal sonogram depicting an in-plane injection at the origin of the radial collateral ligament of the elbow. The needle entry point must be sufficiently proximal in order to obtain a steep enough angle for this injection target

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Fig. 15.14  Cubital tunnel, distal approach. The transducer position is depicted directly over the cubital tunnel. Should a hydrodissection of the nerve within the cubital tunnel be desired, the injection can be started more distally and extended proximally. (a) Photograph depicting patient positioning in a supine position, arm overhead on pillows and elbow slightly flexed. This allows easy access to the volar forearm and medial elbow. (b) Transverse sonogram depicting the ulnar nerve

(arrow) within the cubital tunnel. If utilizing an out-of-plane approach, the needle would be guided to a position alongside the nerve. (c) Transverse sonogram of the ulnar nerve, distal to the cubital tunnel, lying deep to Osborne’s fascia. Closed arrows, ulnar nerve, with multiple fascicles; solid line, desired needle tract, directed from lateral to medial; asterisks, the humeral and ulnar heads of the flexor carpi ulnaris muscle; open arrows, Osborne’s fascia

may release it from its entrapment. Figure  15.14a demonstrates the patient positioned supine with the arm to be injected resting overhead on pillows, exposing the volar forearm. The transducer is laid transversely over the ulnar nerve, with the needle approaching from the distal aspect, out-ofplane to the transducer. Alternatively, a hydrodissection may be started with a transducer position that is distal to the cubital tunnel, first utilizing an in-plane approach to circumferentially surround the nerve with injectate and then changing to an out-of-plane approach to extend the hydrodissection proximally into the cubital tunnel. A short-axis sonographic view of the ulnar nerve in the cubital tunnel is shown in Fig. 15.14b, c, the nerve is shown distal to the cubital tunnel, between the two heads of the flexor carpi ulnaris.

• A short-axis needle approach to the ulnar nerve in the cubital tunnel requires a transducer with a small footprint and a steep needle angle. Should a short-axis approach to the ulnar nerve be desired, such as for a nerve block, it should be performed proximal or distal to the cubital tunnel.

Pearls and Pitfalls: Elbow • Placing the patient supine with arm overhead provides good access to the medial elbow for the cubital tunnel, medial epicondyle, and ulnar collateral ligament. The ulnar nerve proximal to the cubital tunnel can also be injected in this position.

Wrist Carpal Tunnel (Fig. 15.15) Ultrasound guidance in carpal tunnel injections offers many benefits, including avoidance of intra-tendinous or ­intraneural injection, avoidance of the palmar cutaneous and recurrent motor branches of the median nerve, assurance that the injection is actually deep to the transverse carpal ligament of the wrist, and the ability to hydrodissect the nerve from the underside of the transverse carpal ligament. The carpal tunnel can be approached from proximally, or transversely from the ulnar aspect. Whichever the approach, this should be considered an advanced injection.

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a

b

c

d

Fig. 15.15  Carpal tunnel injection. The transducer is placed over the transverse carpal ligament, distal to the pisiform. (a) Patient and transducer positioning for an ulnar approach. The patient is supine, arm overhead. Note the orientation of the transducer, toggled perpendicular to the inclination of the carpal tunnel. (b) Patient and transducer positioning for a proximal approach. This approach first requires identification of the palmar cutaneous branch of the median nerve. The needle should be directed to the ulnar edge of the median nerve, at the deep surface of the transverse carpal ligament. (c, d) Transverse sonograms

of the carpal tunnel, demonstrating the ulnar artery and nerve and an ulnar in-plane injection approach to the carpal tunnel. In (c), the ulnar artery is seen immediately to the left (ulnar direction) of the needle on the image. In (d), the transducer has been moved in a radial direction to uncover a more suitable needle insertion point on the skin, to avoid the ulnar artery, which is visible only at the left (ulnar) edge of the image. The injection target is the ulnar edge of the median nerve, at the undersurface of the transverse carpal ligament. Asterisk, ulnar artery; open arrows, transverse carpal ligament; closed arrows, median nerve

The carpal tunnel is inclined such that the tunnel is deeper distally than it is proximally. For this reason, an approach from the distal aspect is difficult, as the needle trajectory will not be parallel to the inclination of the carpal tunnel. Additionally, the skin of the palm is more sensitive than that of the volar wrist, making a distal approach more uncomfortable for the patient. The bony attachments of the transverse carpal ligament are located on the pisiform and scaphoid proximally and hook of the hamate and trapezium distally. Prior to performing the injection, these bony landmarks the transverse carpal ligament, and of course the median nerve should be identified. The transducer is then placed over the transverse carpal ligament and toggled so that the ultrasound beam is perpendicular to the inclination of the carpal tunnel and anisotropy of the median nerve is eliminated. If approaching from the proximal aspect, the palmar branch of the median nerve, which separates from the median nerve and travels superficial to the transverse carpal ligament, should be identified. If approaching from the ulnar side, the ulnar nerve and artery must be avoided.

The median nerve is best hydrodissected from the undersurface of the transverse carpal ligament by first separating the two at the ulnar aspect of the median nerve and then extending the hydrodissection laterally. This is most facile with an approach from the ulnar side (Fig. 15.15a), but this is also possible with a proximal approach (Fig. 15.15b), with the needle tip first inserted at the ulnar edge of the median nerve. The ulnar approach necessitates avoiding the ulnar artery and nerve. Figure 15.15c, d illustrates the importance of choosing a transducer position that allows the desired needle trajectory, a technique applicable to many injections. When the transducer is placed too far toward the ulnar side of the wrist, it becomes difficult to obtain a needle trajectory that sufficiently avoids the ulnar artery, when aiming at the ulnar edge of the median nerve (Fig.  15.15c). Moving the transducer in a lateral (radial) direction, the skin insertion point can also be farther lateral, with a more acceptable needle trajectory (Fig. 15.15d).

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Fig. 15.16  Wrist first dorsal compartment injection. (a) Photograph depicting patient and transducer positioning. The patient is seated alongside the exam table, and the transducer is placed short axis to the tendons, over the cortex of the radial styloid process. The needle approach is from the distal aspect, out-of-plane to the transducer. (b)

Transverse sonogram of the first dorsal compartment over the radial styloid process. Asterisk, needle tip between the abductor pollicis longus and extensor pollicis brevis tendons; open arrows, first dorsal compartment tendon sheath; asterisk, basilic vein

 irst Dorsal Compartment (Fig. 15.16) F The aim of this injection is to place corticosteroid between the tendon pair within the first dorsal compartment (abductor pollicis longus and extensor pollicis brevis) and their common tendon sheath. An intra-tendinous injection should be avoided. Figure 15.16a illustrates an out-of-plane approach from the distal aspect. Because of the presence of the radial artery deep to the first dorsal compartment and distal to the radial styloid process, the injection should be performed more proximally, over the radial styloid process (Fig. 15.16b). The patient is seated, facing the examiner, the transducer is placed transversely over the first dorsal compartment at the level of the radial styloid process, and the division between the two tendons is identified. Upon penetrating the tendon sheath, the bevel is turned downward, and while injecting lidocaine, the needle tip is advanced, hydrodissecting the sheath away from the tendon pair. Figure  15.16b shows a transverse sonogram in which the needle has been placed between the two tendons; such a deep needle position is not entirely necessary. The hydrodissection should be continued until an approximately 3-cm-long fluid space is created within the tendon sheath, prior to injecting corticosteroid. If the extensor retinaculum is thickened, it may also be injected at several spots, with the same out-of-plane approach.

should give a similar appearance as is shown in a midtarsal joint injection in Fig. 15.26.

 humb Carpometacarpal Joint (Not Shown) T The thumb carpometacarpal (CMC) joint is frequently arthritic, and good relief can be obtained with a corticosteroid injection. The injection should avoid traumatizing the first dorsal compartment of the wrist. The transducer is laid longitudinally along the joint, and the needle approach is short axis, aiming for the V-shaped notch in the joint. This

Pearls and Pitfalls: Wrist • Placing the patient supine, forearm and hand resting on pillows above their head, allows access to the carpal tunnel from both the proximal and ulnar aspects. • For the first dorsal compartment, inject the tendon sheath over the cortex of the radial styloid process, to provide a bony backstop for the needle. Distal to the radius, the radial artery passes deep to the tendon sheath.

Hand A high-frequency transducer should be used for all hand injections, principally to identify nerves and arteries, so that they may be avoided.

 CP and IP Joints (Not Shown) M These injections are performed out-of-plane, with the transducer placed longitudinally along the dorsal aspect of the joint. The proper digital arteries surround the joint, and these should be well visualized with Doppler imaging and marked on the skin. Since these constitute an end-arterial supply to the fingers, they must not be damaged, as an ischemic finger could result. Ultrasound guidance allows avoidance not only of these arteries but also the proper digital nerves and the articular cartilage of the joint. Successful needle placement should place the needle tip at the midpoint of the “V” shape of the joint space, deep to the synovium.

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a

227

b

Fig. 15.17  A1 pulley injection for trigger finger. (a) Photograph showing patient and transducer positioning. The patient is seated alongside the exam table, forearm supinated on the table. The transducer is laid transversely across the A1 pulley. (b) Transverse sonogram depicting the A1 pulley overlying the flexor digitorum superficialis (FDS) and

flexor digitorum profundus (FDP) tendons. X, desired needle tip locations for placing injectate between the tendons and the A1 pulley; arrows, A1 pulley; asterisks, common digital arteries, showing Doppler signal

Upon injection in the joint space, the synovium and capsule will be seen to rise.

the acetabulum, over the femoral head, and along the femoral neck, to a point proximal to the intertrochanteric line; then it reflects back on its undersurface, to insert at a point approximately halfway down the femoral neck. The morphology of the hip joint capsule is illustrated by the arthrogram shown in Fig. 15.18b. Needle placement at the distal femoral neck has the potential to penetrate through both layers of the reflected capsule and therefore end up being extracapsular. The lateral femoral circumflex artery and its accompanying nerve lie superficial to the anterior femoral neck and should be identified by Doppler. The patient is placed supine, and the curved, low-frequency transducer is placed along the axis of the femoral neck (Fig. 15.18a). After anesthetizing the skin, a long needle (typically 3.5 inches) is advanced in-plane and guided around the lateral femoral circumflex artery and its accompanying nerve, aiming for the junction between the femoral head and neck (Fig. 15.18c). Both the fascial planes encountered along the needle tract and the hip joint capsule are sensitive, so they should be anesthetized before penetrating them with the needle tip. Once reaching the cortex of the femur, a test injection of 1–2 cc of sterile normal saline with approximately 0.2 cc of air is helpful to confirm intracapsular placement; the bubble should pass over the anterior femoral head during the injection or at least spread out along the femoral head-neck junction. Using too much air in this maneuver may obscure the injection target. Expansion of the joint capsule may also be seen. With inadvertent placement of the needle tip deep to the reflected portion of the capsule (i.e., too distal), the distal edge of the capsule may rise, but the injection is actually extracapsular.

 rigger Finger (Fig. 15.17) T The aim of this injection is to place corticosteroid between the thickened A1 pulley in the distal palm and the flexor digitorum superficialis and profundus tendons (or the flexor pollicis longus tendon, in the case of trigger thumb). Viewed in the axial plane, the A1 pulley demonstrates a fibrillar echotexture on the volar surface of the tendons, but medially and laterally, the pulley is anisotropic and therefore hypoechogenic. Thickening of the pulley is typically seen when triggering is present. The transducer is placed transversely over the A1 pulley, and the approach is from the distal aspect (Fig.  15.17a), aiming to inject both to the radial and ulnar sides of the flexor tendons and avoiding the proper digital arteries and their accompanying nerves (Fig. 15.17b). A thickened A1 pulley may also be itself injected. Injections of the A1 pulley of the thumb require identification of the proper digital nerve that supplies the radial side of the thumb. This nerve crosses the FPL tendon sheath, is vulnerable during this injection, and should be carefully avoided. Failure to visualize this nerve should constitute grounds for discontinuing the procedure.

Hip and Pelvis  ip Joint (Fig. 15.18) H Hip injections can be utilized diagnostically with local anesthetic, to distinguish between intra-articular and extra-­ articular pain generators and therefore pare down what is usually an extensive differential diagnosis, or t­ herapeutically. Hip joint injections are actually intracapsular, as opposed to targeting the joint space itself. The hip capsule extends from

 soas Bursa (Not Shown) P The psoas bursa extends from anterior to the hip joint, where it communicates with that joint in approximately 30% of cases, to the insertion of the iliopsoas tendon onto the lesser

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E. S. Adams

b

c

Fig. 15.18  Hip joint injection. (a) Photograph depicting patient and transducer positioning. A sufficiently large area of skin should be exposed to allow maintenance of a sterile field. The transducer is oriented over the long axis of the femoral neck. Sweeping the transducer side to side or turning it short axis to the femoral neck can help delineate the orientation of the femoral neck; some are more vertical, others

more horizontal. (b) Hip arthrogram showing the morphology of the hip capsule. Its distal margin is redundant, with its undersurface folding back proximally to insert on the bony cortex. (c) Sonogram showing desired needle trajectory for hip joint capsule injection. Arrow, lateral circumflex femoral vessels, with the artery showing Doppler signal. A steep needle angle is often required to avoid the neurovascular bundle

trochanter of the femur. As the iliopsoas curves over the anterior aspect of the hip joint, the bursa is under compression, so fluid collections are not typically seen at this location in cases of psoas bursitis or psoas tendinopathy, but rather more distally. The preferred injection location is over the anterior acetabulum, as the distal aspect of the bursa is much deeper and has overlying neurovascular structures. The psoas tendon lies in a shallow fossa at this location. The patient is placed supine, and the transducer is oriented transversely over the anterior acetabulum. The needle is introduced in-­ plane from the lateral aspect, avoiding the lateral femoral

cutaneous nerve, and then advanced to the undersurface of the psoas tendon, and the injection should lift the tendon of the iliopsoas away from the bone.

 acroiliac (SI) Joint (Fig. 15.19) S The sacroiliac joint may be approached transversely or longitudinally, from the caudal aspect. Both are difficult and should be practiced repeatedly on cadavers before being attempted on the living. For the transverse approach, the curved low-frequency ultrasound transducer is placed in the axial plane across the SI joint at the level of the posterior

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superior iliac spine (PSIS) and then moved caudally to the level of the S2 neural foramen. At this position caudal to the PSIS, the PSIS no longer overhangs the joint, and in most patients, the joint space can be visualized sonographically (Fig. 15.19b). The needle is in-plane to the transducer, with an approach from the medial side (Fig. 15.19a). A steep needle angle is typically required. The inclination of the sacrum requires that the transducer be toggled caudally, if the ultrasound beam is to be in an orthogonal relationship to the bony cortex and thus produce a good image. This is demonstrated in Fig.  15.19a. This inclination of the transducer makes it more challenging to place the needle within the middle of the ultrasound beam, so needle conspicuity is difficult for this injection. Because the PSIS overhangs the joint slightly, it is also difficult to see the inclination of the joint space and thus determine the appropriate needle trajectory. In some patients, the joint space may be seen by heel-toeing the transducer, directing it laterally, to view under the overhanging PSIS. The longitudinal approach to the SI joint (not shown) is more difficult and requires that the transducer be centered in the joint longitudinally, with the needle directed cephalad, in-plane to the transducer. The transducer will be rotated with its superior aspect laterally about 10° with respect to the sagittal plane, to match the orientation of the SI joint. Whichever approach to the SI joint is used, transverse or longitudinal, once the needle is in the joint, one should be able to see the swirling of injectate within the joint with Doppler imaging, and this should be considered part of the injection protocol.

 rochanteric Bursa (Fig. 15.20) T The trochanteric bursa overlies the posterior facet of the greater trochanter, with its anterior margin overlying the ­gluteus medius anterior band (Gmed AB) insertion at the lateral facet. Typically, the bursa is no thicker than the width of

a

a 22 gauge needle, so the traditional LMG technique, with the needle perpendicular to the greater trochanter, is unlikely to find the correct layer. Injection into a tendon is the more likely outcome. The sonographic technique for visualizing the bursa involves first obtaining a long-axis view of the Gmed AB to include the distal tip of the insertion and the posterior facet (Fig.  15.20b) The bursa can be seen as a hypoechogenic line that extends from the superficial surface of the Gmed AB posteriorly over the posterior facet. In disease, the bursa may be filled with echogenic debris. Approach is from inferoposterior, in-plane to the transducer, as parallel to the bursa as possible (Fig. 15.20a). Pearls and Pitfalls: Hip and Sacroiliac Joint • The nerve accompanying the lateral circumflex femoral artery is very sensitive if punctured with the needle. After locating the lateral femoral circumflex artery with Doppler, identify the nerve. • For hip joint injections, if the lateral circumflex femoral artery and its nerve are found to be in a position that makes avoiding them difficult, consider putting the patient in a lateral decubitus position, and inject the lateral aspect of the femoral head-neck junction. • The angle of the femoral neck, with respect to the sagittal plane, is variable, typically being more vertical in taller, slender persons. Needle accuracy is maximized if the transducer is oriented parallel to and midline on the femoral neck. • For a long-axis injection of the SI joint, the joint space appears as an anechogenic void when the transducer is perfectly centered over the joint. Move back and forth between the sacrum and ileum, and then find the midpoint between the two, rotating the transducer by increments until the image just captures the edge of the cortex all along its length.

b

Fig. 15.19  Sacroiliac (SI) joint injection. (a) Photograph demonstrating patient and transducer positioning. Note the angle to which the transducer is toggled, perpendicular to the inclination of the sacrum. This produces a brighter image of the sacral cortex. (b) Transverse

sonogram demonstrating the SI joint at a level about 2 cm caudal to the posterior superior iliac spine, with desired needle trajectory shown by a white line. Note that the needle trajectory must be in-line with the orientation of the SI joint if the joint is to be entered successfully

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a

b

Fig. 15.20  Trochanteric bursa injection. (a) Photograph depicting patient and transducer positioning. The patient is in a lateral decubitus position. The transducer is oriented long axis to the gluteus medius anterior band (Gmed AB), which lies approximately on a line between the anterior superior iliac spine and the lateral facet of the greater trochanter. Once the enthesis of the Gmed AB is visualized long axis, the transducer is moved posteriorly until the posterior facet of the greater

trochanter comes into view. (b) Sonogram depicting the trochanteric bursa (arrows) overlying the gluteus medius anterior band (Gmed AB) to the left side of the image, which is anterosuperior, and the posterior facet of the greater trochanter on the right side of the image. Asterisks: effusion within the trochanteric bursa. The bursa should be seen to expand at this location with injection

Table 15.3  Nerve blocks for selected tendon injection targets Target tendon Supraspinatus Common extensor tendon, lateral epicondyle Common flexor tendon, medial epicondyle Gluteus medius and minimus Patellar tendon Achilles tendon Plantar fascia

Motor nerve Suprascapular Radial

Sensory nerve Supraclavicular Posterior antebrachial cutaneous

Location of block Suprascapular notch Spiral groove of radius

Ulnar

Medial antebrachial cutaneous

Superior gluteal nerve

Subcostal (T12), lateral femoral cutaneous

Cubital tunnel or arcade of Struthers, medial antebrachial cutaneous nerve adjacent to basilic vein Greater sciatic foramen, cephalad edge of piriformis Saphenous nerve in adductor canal, common fibular at lateral knee Mid-calf for both nerves Approx. 10 cm proximal to medial malleolus for tibial nerve; sural nerve adjacent to small saphenous vein

Branches of saphenous, Same common fibular Tibial Sural, saphenous Tibial Medial calcaneal branch of tibial, sural, saphenous, depending on needle insertion location

• In trochanteric bursa injections, observation of expansion of the bursa over the posterior facet is confirmatory, so this structure should be included in the ultrasound view during the injection. Success with this injection also depends on the ability to image the anterior band of the gluteus medius.

Knee (Table 15.3)  uprapatellar Recess (Figs. 15.3 and 15.21) S The suprapatellar recess route avoids any potential contact with articular cartilage or meniscus. When the patient has a small knee effusion, this injection is relatively easy but can be challenging when the knee is dry. While visualizing the distal quadriceps femoris tendon long axis, the patient should

be asked to perform an isometric quadriceps contraction, which will lift the tendon and draw any joint fluid into the suprapatellar recess. Most patients have a small amount of intra-articular fluid, and this maneuver will help identify the injection target. The patient is supine for the injection, knee either fully extended or flexed no more than about 15° over a pillow or bolster. The transducer is first placed longitudinally over the quadriceps tendon, to identify structures and any potential fluid space to target, and then turned transversely. The approach is from the lateral side, in-plane to the transducer (Fig.  15.3). When the knee is dry, the suprapatellar recess will need to be opened with lidocaine or saline, and it can be difficult to find the appropriate layer. A successful injection will demonstrate the suprapatellar recess opening symmetrically, usually demonstrating a bow-tie shape, along the deep surface of the quadriceps tendon (Fig. 15.21).

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dial tibia. The transducer is first placed long axis along the distal pes tendons and then rotated into an orientation parallel to the tibia. A successful injection should see expansion of the bursa and lifting of the tendons. If the sonographic exam fails to demonstrate fluid in the bursa, the patient may not have pes anserine bursitis, and an alternative explanation for pain in that area should be sought. The differential diagnosis includes saphenous nerve entrapment, pes anserinus tendinopathy, pathology of the distal medial collateral ligament, and stress fracture or other bony pathology.

Fig. 15.21  Transverse sonogram demonstrating a knee joint injection into suprapatellar recess. This location avoids any potential iatrogenic injury to articular cartilage. Asterisks: bow tie-shaped suprapatellar recess being opened with injectate volume. See Fig. 15.3 for patient and transducer positioning

 repatellar Bursa (Not Shown) P This relatively simple injection can be approached from any angle, long or short axis. In acute cases of prepatellar bursitis with an effusion, identification of the bursa is straightforward, but in chronic cases, the bursa may contain hypertrophied synovium and little fluid. The synovium may show hyperemia by Doppler imaging. Test injections of lidocaine may be needed to confirm opening of the bursa, to ensure correct placement. Since the bursa is very superficial in patients of normal weight, care should be taken to not penetrate the ultrasound transducer with the needle. It may be helpful to briefly lift the transducer away from the skin during initial needle advancement and then place the transducer back on the skin to assess the needle trajectory.  es Anserinus Bursa (Fig. 15.22) P The pes anserinus bursa lies between the pes anserinus tendon group and the medial cortex of the proximal tibia. Approaching from the distal aspect (Fig. 15.22a) allows a needle trajectory that passes deep to, rather than through, the pes anserinus tendons. The saphenous nerve and vein should be identified by Doppler, as they are adjacent to the bursa. The patient is placed supine, with the hip on the side to be injected externally rotated, to expose the anterome-

 aker’s Cyst (Not Shown) B A true Baker’s cyst will expand the potential space between the semimembranosus tendon and the medial gastrocnemius. Since the semimembranosus tendon is inclined to reach the posterior tibial plateau, a short-axis view of the tendon will require toggling the transducer to point it more cephalad, to avoid tendon anisotropy. The medial gastrocnemius demonstrates an eccentrically placed tendon at this location that has a triangular cross section. A Baker’s cyst typically contains a superficial and a deep component, and these may need to be separately aspirated, which can often be accomplished from a single needle entry point. This can be approached from any angle, as long as sensitive structures are avoided. Pearls and Pitfalls: Knee • Locating the suprapatellar recess in a dry knee may be aided by placing the bevel of the needle against the undersurface of the patellar tendon (bevel up) and injecting lidocaine or saline. This requires a needle entry point that is slightly deeper than usual, to allow an upward inclination of the needle. • The synovial space connecting the suprapatellar recess to the knee joint passes dorsal to the suprapatellar fat pad and may be used as an injection target in difficult cases. • Injection in the notch of the knee, from an anterolateral or anteromedial approach, risks injection into the anterior cruciate ligament.

Ankle  alocrural Joint (Fig. 15.23) T LMG injections of the ankle talocrural joint risk iatrogenic injury to the talar dome articular cartilage, tendons of the anterior ankle, dorsalis pedis artery, and superficial and deep fibular nerves, as does a poorly performed guided injection. The joint can be injected from multiple angles, as long as sensitive structures are avoided. For an approach from the lateral side, the transducer is placed longitudinally over the

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joint and the articular cartilage identified. An in-plane approach [23] from the distal aspect simplifies the task of avoiding overlying tendon and arterial structures, but not all patients are able to adequately plantarflex their ankle. In addition, the shallow needle angle that this approach requires may not allow the needle tip to be placed deep to the synovium, which is seen as a triangular structure penetrating into the anterior joint line, when viewed in the sagittal plane. A short-axis approach is therefore preferred. Figure 15.23a demonstrates a needle entry point that is lateral to the exten-

sor digitorum longus tendons, with a transducer placement that is slightly lateral to the dorsalis pedis artery and deep fibular nerve. Once the needle tip is deep to the synovium of the joint (illustrated in Fig. 15.23b), injection should lift the synovium and joint capsule.

 nkle Tendon Sheath Injection (Fig. 15.24) A All of the tendons crossing the ankle joint except the Achilles tendon are enclosed by synovial sheaths, which may develop tenosynovitis. In acute cases, there will likely be an effusion

a

b

c

Fig. 15.22  Pes anserinus bursa injection. (a) The transducer is oriented along the axis of the tibia and is therefore oblique to the pes anserinus tendons. The needle approach is in-plane to the transducer, from caudad to cephalad. (b) Sonogram oriented obliquely to pes anserinus

a

Fig. 15.23  Talocrural joint. (a) A needle entry point that is lateral to the extensor digitorum longus tendons, with a transducer placement that is slightly lateral to the dorsalis pedis artery and deep fibular nerve.

tendons, demonstrating the desired needle tract between the tendons and the medial tibial cortex. Arrows: pes anserinus tendons. (c) Sonogram oriented parallel to the medial tibial cortex, showing a needle tip (white dot) in the pes anserinus bursa

b

(b) Once the needle tip is deep to the synovium of the joint, injection should lift the synovium and joint capsule

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surrounding the tendon, making injection guidance easier. In chronic cases, the tendon sheath will be thickened and possibly adherent to the tendon, so it must be hydrodissected free of the tendon before injection of corticosteroid. The approach is typically from the distal aspect of the tendon, and the transducer is alternated between an orientation short and long axis to the tendon during needle advancement to monitor the needle position. Figure 15.24a illustrates patient and transducer positioning, with the needle approaching out-­ of-­plane from the distal aspect. The needle should never enter the tendon. If hydrodissecting the tendon sheath free of the tendon, the bevel is turned toward the tendon, and volume is injected while passing through the sheath. Upon reaching the potential space between sheath and tendon, the space will expand, and the needle can be advanced into that fluid space, carrying the hydrodissection proximally. A successful injection will show fluid circumferentially around the tendon. Figure 15.24b demonstrates a transverse sonogram of the fibular tendons, with a desirable needle target illustrated.

 arsal Tunnel (Not Shown) T Tarsal tunnel syndrome results from compression of the tibial nerve or its branches in the tarsal tunnel. An ultrasound exam should discern the presence of masses within this space, such as a ganglion cyst, osteophytes, accessory muscle (e.g., flexor digitorum accessorius longus), extension of muscle belly (e.g., flexor hallucis longus) distally into the tarsal tunnel, or swollen tendons. Injections can target such pathology, or the injection can simply be placed deep to the flexor retinaculum at the medial ankle. In this case, ultrasound guidance allows assurance that the injectate is not placed within a tendon, nerve, or blood vessel. The transducer is placed transversely over the tarsal tunnel. A needle approach from proximal to distal, out-of-plane to the transducer, allows easier avoidance of the medial and lateral plan-

a

tar nerves, but distal or dorsal approaches are also acceptable, with successful avoidance of sensitive nearby structures. The medial calcaneal nerve, which arises from the tibial nerve proximal to its bifurcation into the medial and lateral plantar nerves, is difficult to see in its subcutaneous location posterior to the tibial nerve, so a dorsal approach may be more difficult in this regard.

Foot  lantar Aponeurosis (Plantar Fascia) (Fig. 15.25) P Plantar fasciopathy typically appears sonographically as a thickened and hypoechogenic plantar aponeurosis at its origin. Typically, the central cord is involved. When corticosteroid is used, this injection is placed along the deep surface of the plantar aponeurosis, as close to its origin as possible (Fig. 15.25b). When properly placed, the injectate should lift the plantar aponeurosis away from the calcaneus. Attempting to inject along the deep surface of the plantar fascia more than a few millimeters distal to the calcaneus will be difficult, as the plantar fascia is the aponeurosis of the flexor digitorum brevis and is therefore closely adherent to that muscle. The patient is placed in a prone position, with feet just off the end of the exam table. The ultrasound transducer is oriented long axis with respect to the plantar aponeurosis. If injecting corticosteroid, low volumes of injectate are indicated, to avoid extravasation of corticosteroid into the plantar fat pad, which may cause fat pad atrophy. With a tibial nerve block, the plantar aponeurosis can be approached from the posterior heel (Fig. 15.25a), which allows fenestration of the aponeurosis if desired. Without a tibial nerve block, this approach is too painful, and entering from the lateral heel in the coronal plane is preferred, with local anesthesia or a sural nerve block. The sural nerve should also be located at the

b

Fig. 15.24  Injection of the fibularis longus and brevis tendon sheaths. Additional sterile gel is helpful because of the concavity of the skin surface at the posterolateral ankle. (a) Patient and transducer positioning for the injection. This demonstrates a distal approach, out-of-plane

with the transducer. (b) Transverse sonogram of the fibularis longus (open arrows) and brevis (closed arrows) tendons. The needle tip should be aimed at the position denoted by an asterisk. SSV: small saphenous vein

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E. S. Adams

lateral heel and marked at the lateral heel. At the level of the ankle, the sural nerve lies adjacent to the small saphenous nerve and should be blocked at that location.

 idtarsal or MTP Joint (Fig. 15.26) M The dorsalis pedis artery should be first located for a midtarsal joint injection, and for an MTP joint injection, the digital arteries should be located, especially since these are end-­arterial supplies for the toes. Damage to these arteries can result in ischemia to a toe, so despite the apparent benign nature of this injection, more advanced ultrasound skills are desirable. For any midtarsal or MTP joint, the transducer is laid longitudinally along the dorsal aspect of the joint, and the needle approach is out-of-plane to the transducer. Whether to approach from the medial or lateral side depends on the presence of vulnerable structures. As always, the needle tip should not contact articular cartilage, and it must be deep to the synovium to be considered intra-articular. Figure  15.26a depicts patient and transducer positioning for an injection of the first tarsometatar-

a

 orton’s Neuroma (Not Shown) M Morton’s neuromas occur in the common digital nerves of the foot arising from the medial and lateral plantar nerves. They lie plantar to the transverse intermetatarsal ligament. When scanning diagnostically, these can be seen extruding from between the plantar surfaces of the metatarsal (MT) heads upon squeezing the foot at the level of the MT heads (Mulder’s test). For injections, the transducer can be placed either the dorsal or plantar aspect of the MT heads, with the needle approaching from distally, within the interspace. A combination of long-axis and short-axis views should be utilized, when advancing the needle, with particular attention to avoiding the common and proper digital arteries, as these provide an end-arterial supply to the toes. Intermetatarsal bursitis and Morton’s neuroma may coexist, with the bursa lying dorsal to the transverse intermetatarsal ligament.

b

Fig. 15.25  Plantar fascia central cord injection. The dorsal approach requires a tibial nerve block. (a) Patient and transducer positioning for a dorsal approach. (b) Longitudinal sonogram of the plantar fascia cen-

a

sal joint, and Fig. 15.26b demonstrates the sonographic image obtained from this transducer position.

tral cord, showing the appropriate needle trajectory to reach a point at the distal tip of the origin of the plantar fascia on the calcaneus. Note that the trajectory must be sufficiently steep

b

Fig. 15.26  Injection of the first tarsometatarsal joint. Identification of branches of the superficial fibular nerve and of the dorsalis pedis artery is necessary prior to this injection. (a) Patient and transducer positioning. With the patient in a semi-recumbent position, hips and knees

flexed, the foot can be placed flat on the exam table, increasing stability. (b) Longitudinal sonogram of the first tarsometatarsal joint. The needle should be directed to the bottom of the “V” of the joint (position marked with an asterisk), when the joint is viewed long axis

15  Ultrasound Guidance of Procedures

Consideration should be given to a nerve block, as the toe interspaces are extremely sensitive. Pearls and Pitfalls: Ankle and Foot • When performing a sural nerve block, the sural nerve is easily identified by its position adjacent to the small saphenous vein at the posterolateral ankle. • Perform a tibial nerve block proximal to the origin of its medial calcaneal branch. • In tenosynovitis, the tendon sheath is typically thickened, and distinguishing sonographically between the sheath and tendon may be easier, even if no effusion is present. Acknowledgment The author gratefully acknowledges Erin Sigler, MA, and Samatha Kropp, MS2, for their contributions to the photographs in this chapter.

References 1. Muir JJ, Curtiss HM, Hollman J, Smith J, Finnoff JT. The accuracy of ultrasound-guided and palpation-guided peroneal tendon sheath injections. Am J Phys Med Rehabil. 2011;90(7):564–71. 2. Rutten MJ, Collins JM, Maresch BJ, Smeets JH, Janssen CM, Kiemeney LA, et al. Glenohumeral joint injection: a comparative study of ultrasound and fluoroscopically guided techniques before MR arthrography. Eur Radiol. 2009;19(3):722–30. 3. Hashiuchi T, Sakurai G, Morimoto M, et  al. Accuracy of the biceps tendon sheath injection: ultrasound-guided or unguided injection? A randomized controlled trial. J Shoulder Elb Surg. 2011;20:1069–73. 4. Cunnington J, Marshall N, Hikde G, Bracewell C, Isaacs J, Platt P, et al. A randomized, double-blind, controlled study of ultrasound-­ guided corticosteroid injection into the joint of patients with inflammatory arthritis. Arthritis Rheum. 2010;62(7):1862–9. 5. Luz KR, Furtado RNV, Nunes ICCG, Rosenfeld A, Fernandes ARC, Natour J. Ultrasound-guided intra-articular injections in the wrist in patients with rheumatoid arthritis: a double- blind, randomised controlled study. Ann Rheum Dis. 2008;67(8):1198. 6. Curtiss HM, Finnoff JT, Peck E, Hollman J, Muir J, Smith J.  Accuracy of ultrasound-guided and palpation-guided knee injections by an experienced and less-experienced injector using a superolateral approach: a cadaveric study. PM R. 2011;3(6): 507–15. 7. Khosla S, Thiele R, Baumhauer JF.  Ultrasound guidance for intra-articular injections of the foot and ankle. Foot Ankle Int. 2009;30(9):886–90. 8. Sabeti-Aschraf M, Lemmerhofer B, Lang S, et al. Ultrasound guidance improves the accuracy of the acromioclavicular joint infiltration: a prospective randomized study. Knee Surg Sports Traumatol Arthrosc. 2011;19(2):292–5. 9. Finnoff JT, Nutz DJ, Henning PT, Hollman JH, Smith J. Accuracy of ultrasound-guided versus unguided pes anserinus bursa injections. PM R. 2010;2(8):732–9. 10. Wisniewski SJ, Smith J, Patterson DG, Carmichael SW, Pawlina W. Ultrasound-guided versus nonguided tibiotalar joint and sinus tarsi injections: a cadaveric study. PM R. 2010;2(4):277–81. 11. Smith J, Maida E, Murthy NS, Kissin EY, Jacobson JÁ. Sonographically guided posterior subtalar joint injections via the sinus tarsi approach. J Ultrasound Med. 2015;34:83–93.

235 12. Reach JS, Easley ME, Chuckpaiwong B, Nunley JA 2nd. Accuracy of ultrasound guided injections in the foot and ankle. Foot Ankle Int. 2009;30(3):239–42. 13. Peck E, Lai JK, Pawlina W, et al. Accuracy of ultrasound-guided versus palpation-guided acromioclavicular joint injections: a cadaveric study. PM R. 2010;2:817–21. 14. Aly A-R, Rajasekaran S, Ashworth N.  Ultrasound-guided shoulder girdle injections are more accurate and more effective than landmark-­guided injections: a systematic review and meta-analysis. Br J Sports Med. 2015;49:1042–9. 15. Dogu B, Yucel SD, Sag SY, et  al. Blind or ultrasound-guided corticosteroid injections and short-term response in subacromial impingement syndrome: a randomized, double-blind, prospective study. Am J Phys Med Rehabil. 2012;91:658–65. 16. Bhayana H, Mishra P, Tandon A, Pankaj A, Pandey R, Malhotra R. Ultrasound guided versus landmark guided corticosteroid injection in patients with rotator cuff syndrome: randomized controlled trial. J Clin Orthop Trauma. 2018;9S:S80–5. 17. Wu T, Dong Y, Song H, Fu Y, Li J. Ultrasound-guided versus landmark in knee arthrocentesis: a systematic review. Sem Arthritis Rheum. 2016;45:627–32. 18. Petscavage-Thomas J, Gustas C. Comparison of ultrasound-guided to fluoroscopy-guided biceps tendon sheath therapeutic injection. J Ultrasound Med. 2016;35:2217–21. 19. Scillia A, Issa K, McInerey VK, Milman E, Baltazar R, Dasti U, Festa A.  Accuracy of in vivo palpation-guided acromioclavicular joint injection assessed with contrast material and fluoroscopic evaluations. Skelet Radiol. 2015;44:1135–9. 20. De Luigi AJ, Saini V, Mathur R, Saini A, Yokel N. Assessing the accuracy of ultrasound guided needle placement in sacroiliac joint injections. Am J Phys Med Rehabil. 2019;98(8):666–70. 21. Borbas P, Kraus T, Clement H, et al. The influence of ultrasound guidance in the rate of success of acromioclavicular joint injection: an experimental study on human cadavers. J Shoulder Elb Surg. 2012;21:1694–7. 22. Patel DN, Nayyar S, Hasan S, et  al. Comparison of ultrasound-­ guided versus blind glenohumeral injections: a cadaveric study. J Shoulder Elb Surg. 2012;21:1664–8. 23. Rho ME, Chu SK, Yang A, et  al. Resident accuracy of joint line palpation using ultrasound verification. PM R. 2014;6:920–5. 24. Raza K, Lee CY, Pilling D, Heaton S, Situnayake RD, Carruthers DM, Buckley CD, Gordon C, Salmon M.  Ultrasound guidance allows accurate needle placement and aspiration from small joints in patients with early inflammatory arthritis. Rheumatology. 2003;42:976–9. 25. Park KD, Kim TK, Lee J, Lee WY, Ahn JK, Park Y. Palpation versus ultrasound-guided acromioclavicular joint intra-articular cortisone injections: a retrospective comparative clinical study. Pain Physician. 2015;18:333–41. 26. Pourcho AM, Colio SW, Hall MM.  Ultrasound-guided interventional procedures about the shoulder. Phys Med Rehabil Clin N Am. 2016;27:555–72. 27. Cole BF, Peters KS, Hackett L, Murrell GAC. Ultrasound-guided versus blind subacromial corticosteroid injections for subacromial impingement syndrome: a randomized, double-blind clinical trial. Am J Sports Med. 2015;44(3):702–7. 28. Huang Z, Du S, Qi Y, Chen G, Yan W. Effectiveness of ultrasound guidance on intraarticular and periarticular joint injections. Am J Phys Med Rehabil. 2015;94:775–83. 29. Lee JH, Lee JU, Woo SW.  Accuracy and efficacy of ultrasound-­ guided pes anserinus bursa injection. J Clin Ultrasound. 2019;47:77–82. 30. Ackermann PW, Salo P, Hart DA.  Tendon innervation. Adv Exp Med Biol. 2016;920:35–51. PMID 27535247. 31. Bordini B, Veracallo M.  StatPearls, Treasure Island, FL. https:// www.ncbi.nlm.nih.gov/books/NBK513237/.

236 32. Ackermann PW, Bring DK-I, Renström P.  Tendon innervation and neuronal response after injury. In: Maffulli P, Renström P, Leadbetter WB, editors. Tendon injuries basic science and clinical medicine. London: Springer; 2005. p. 287–97.

Recommended Reading Colio SW, Smith J, Pourcho AM.  Ultrasound-guided interventional procedures of the wrist and hand: anatomy, indications, and techniques. Phys Med Rehabil Clin N Am. 2016;27:589–605. Henning PT. Ultrasound-guided foot and ankle procedures. Phys Med Rehabil Clin N Am. 2016;27:649–70. Huges RJ, Ali K, Jones H, Kendall S, Connell DA. Treatment of Morton’s neuroma with alcohol injection under sonographic guidance: follow-­up of 101 cases. Am J Roentgenol. 2007;188(6):1535–9. Lueders DR, Smith J, Sellon JL. Ultrasound-guided knee procedures. Phys Med Rehabil Clin N Am. 2016;27:631–48. Payne JM. Ultrasound-guided hip procedures. Phys Med Rehabil Clin N Am. 2016;27:607–29.

E. S. Adams Pourcho AM, Colio SW, Hall MM.  Ultrasound-guided interventional procedures about the shoulder: anatomy, indications, and techniques. Phys Med Rehabil Clin N Am. 2016;27:555–72. Rand E, Welbel R, Visco CJ. Fundamental considerations for ultrasound-­ guided musculoskeletal interventions. Phys Med Rehabil Clin N Am. 2016;27:539–53. Smith J, Maida E, Murthy NS, Kissin EY, Jacobson JA. Sonographically guided posterior subtalar joint injections via the sinus tarsi approach. J Ultrasound Med. 2015;34:83–93. Soneji N, Peng PWH. Ultrasound-guided interventional procedures in pain medicine: a review of anatomy, sonoanatomy, and procedures. Part VI: ankle joint. Reg Anesth Pain Med. 2016;41(1):99–116. Strakowski JA.  Ultrasound-guided peripheral nerve procedures. Phys Med Rehabil Clin N Am. 2016;27:687–715. Sussman WI, Williams CJ, Mautner K. Ultrasound-guided elbow procedures. Phys Med Rehabil Clin N Am. 2016;27:573–87. Yeap PM, Robinson P. Ultrasound diagnostic and therapeutic injections of the hip and groin. J Belg Soc Radiol. 2017;101(S2):6,1–12.

Rheumatologic Findings

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Ralf G. Thiele, Sarah H. Chung, and Elizabeth T. Jernberg

Approach to the Joint Description For the assessment of rheumatic problems that involve the hand, wrist, or elbow, the patient will typically sit on a regular chair, at an examination table or a desk, across from the examiner [1]. The upper extremity can be placed on a cushion. This provides patient comfort and allows the examiner to slightly manipulate or maneuver the examined joint. For the assessment of rheumatic shoulder conditions, both patient and examiner can sit on rotating stools with wheels. For the ultrasound assessment of the lower extremity, the patient is typically placed prone or supine on the exam table. An assistant can help if the leg needs to be held in a certain position for a prolonged period of time.

Probe Selection When assessing rheumatic problems, the highest-frequency linear probe available should be used. Typically, we use frequencies between 12 and 18  MHz. MSUS should be performed with high-resolution linear transducers (i.e., probes) with frequencies between 6 and 14 MHz for deeper areas to ≥15 MHz for superficial areas [2]. Small footprint probes, or “hockey stick” probes, are not a necessary requirement but can be used for the assessment of small finger joints or structures near the medial or lateral malleolus of the ankle. Curvilinear probes are occasionally used in rheumatology if deeper-seated structures or obese patients are scanned. This

R. G. Thiele Division of Allergy/Immunology and Rheumatology, Department of Medicine, University of Rochester, Rochester, NY, USA S. H. Chung (*) · E. T. Jernberg Division of Rheumatology, Department of Medicine, University of Washington Medical Center, Seattle, WA, USA e-mail: [email protected]

can be particularly helpful for assessment of hip effusions and hip injections. Since rheumatic conditions often involve inflammation of tissues, a sensitive Doppler function is essential. Power Doppler assesses the strength, or power, of blood flow. Color Doppler ultrasound encodes the direction of flow with variable colors. In rheumatology, the presence or absence, as well as the strength, of blood flow in inflamed tissues is of interest—the direction generally plays no role. For this reason, power Doppler is often chosen. With newer machines, color Doppler can be just as sensitive for the detection of flow. The examiner should try both modalities and choose the more sensitive one.

Specific Presets If possible, the use of machine presets for each specific joint should be used. These technical presets typically include frequency, depth, and focal points. If presets are not available, select the highest frequency that the probe can deliver. Adjustments may need to be made for the deeper-seated elbow, shoulder, and hip joints in obese patients. Assessment of inflamed tissues is of great interest in rheumatic diseases. Color and power Doppler ultrasound can help appreciate normal and abnormal blood flow. Knowledge of physiologic vascularity is important for the appreciation of hyperemia in inflammation. Doppler signals that indicate blood flow need to be reliably distinguished from artifacts. If a particular tissue or area is identified in gray-scale (normal settings) ultrasound first, this tissue can then be examined with Doppler ultrasound for the presence of increased blood flow. The area of Doppler flow can be “matched” with an area of gray-scale ultrasound abnormalities. If a Doppler signal is seen over an area that makes no anatomic sense (e.g., a Doppler signal deep to the bony cortex, where sound waves are not reaching), this signal should be considered artifact and thus can be ignored. A Doppler signal that is beating synchronously with the pulse, and that makes anatomic

© Springer Nature Switzerland AG 2021 J. M. Daniels, W. W. Dexter (eds.), Basics of Musculoskeletal Ultrasound, https://doi.org/10.1007/978-3-030-73906-5_16

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sense, is likely to be a real signal. True Doppler signals are reproducibly visualized and also present in orthogonal planes (transverse and longitudinal views) [2]. Fleeting Doppler signals that appear at random places are likely artifacts and should also be ignored. Decreasing the Doppler gain until artifacts deep to the bony cortex disappear can help find the balance between sensitivity and specificity.

Common Problems Finding the etiology of joint swelling is a common problem in rheumatology. History and physical examination can be helpful, but may not always help distinguish involvement of subcutaneous tissue, tendons, ligaments, or joints [3]. A swollen extremity or joint may be due to subcutaneous edema, tenosynovitis, synovitis, or injury. Conventional radiography is often used, but cannot demonstrate soft-tissue changes well. Ultrasound can provide detailed information about proliferative synovial tissue and fluid collections in tendon sheaths and joints, synovial hyperemia, bony erosions, enthesitis, and crystal deposits in gout or chondrocalcinosis [4].

R. G. Thiele et al.

Synovitis (Fig. 16.1a, b) Distension of the joint capsule by proliferation of synovial tissue or increased secretion of synovial fluid is here called synovitis. Without the availability of soft-tissue imaging, joint swelling by any cause is often called synovitis. High-­ frequency ultrasonography allows one to distinguish effusion, synovial proliferation, and synovial hyperemia. This distinction can be important for diagnostic or therapeutic purposes. If fluid is detected, it can be aspirated for diagnostic purposes. If only synovial tissue is detected, an aspiration will not be successful. If synovial hyperemia is detected, treatment for inflammatory arthritis can be considered, or a referral planned. In a healthy joint, synovial tissue is usually not seen sonographically, as the synovial lining is only one to three cell layers thick [5]. Proliferative synovial tissue, the hallmark of inflammatory arthritis, typically has a hypoechoic sonographic appearance. It is interposed between hyperechoic, fibrous joint capsule, anechoic (or “black”) hyaline cartilage, and hyperechoic bony contour. Synovial fluid often has an anechoic appearance. Fluid is displaceable with transducer

a

b

Fig. 16.1 Metacarpophalangeal joint, dorsal long-axis view. Rheumatoid arthritis. Distension of the joint capsule by hypoechoic (gray) synovial tissue and anechoic (black) synovial fluid is seen

between arrows ((a) top). Addition of power Doppler ((b) bottom) shows hyperemia of synovial tissue. Areas of neovascularization appear red orange under Doppler. MC metacarpal head, PP proximal phalanx

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pressure, while synovial tissue is slightly compressible but not displaceable.

Tenosynovitis (Fig. 16.2) Tenosynovitis is identified by distension of the tendon sheath by fluid or synovial tissue [6]. Tenosynovitis is particularly common in wrists and ankles, where tendons are subjected to increased mechanical stress between bones and retinacula. The fibrous tendon sheath is lined with a delicate layer of synovial tissue, and the tendon itself is covered with an additional layer of synovial tissue. These two synovial layers are connected by the mesotendineum. Blood supply to the tendon body itself also runs through this tissue connector. In inflammatory arthritis and tenosynovitis seen in conditions such as rheumatoid arthritis (RA), psoriatic arthritis, or

gonococcal infection, this synovial tissue thickens and fills the space between hyperechoic tendon sheath and hyperechoic tendon fibers. Doppler studies can show hyperemia of this synovial tissue in active inflammation.

Bony Erosion (Fig. 16.3) Many forms of arthritis are associated with the formation of bony erosions. Sonographically, erosions are defined as breaks in the cortical contour seen in two perpendicular planes [6, 7]. Ultrasonography detects more erosions than conventional radiography, particularly early in the disease [8]. Bony erosions in a characteristic pattern and distribution are a hallmark feature of rheumatoid arthritis. Proximal interphalangeal (PIP) joints, metacarpophalangeal (MCP) joints, wrists, elbows, and metatarsophalangeal (MTP) joints

Synovial proliferation Tendon

Synovial proliferation

Short axis view

Synovial proliferation

Tendon

Fig. 16.2  Tenosynovitis. Chronic foreign-body reaction after wood splinter entered dorsal wrist. Long-axis view over dorsal wrist (top); short-­ axis view (bottom)

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Fig. 16.3  Metacarpophalangeal joint, dorsal long-axis view. Rheumatoid arthritis. Distension of joint capsule is seen (arrow). Bony erosion shows as discontinuity of bony contour of metacarpal head (between arrowheads). MC metacarpal head, PP proximal phalanx

are particularly affected, often in a symmetric distribution [9]. Ultrasonography is more sensitive than conventional radiography in detecting these erosions, particularly in early disease. In RA, these erosions are often associated with invading synovial pannus tissue. This tissue can also be detected sonographically. Osteoarthritis (OA) is occasionally associated with bony erosions. This can then be called “erosive osteoarthritis.” These erosions affect joints that are typically affected by OA, including distal interphalangeal (DIP) joints, the first carpometacarpal (CMC) joint, shoulder, hip, knee, and forefeet. In contrast to the marginal erosions of RA, the erosions of OA are often centrally located and are not associated with invading pannus tissue. Bone spur formation can be observed in the same joint. This would not be seen in RA.  In gout, erosions can be associated with marginal bony overhangs, a characteristic feature of gout. Gouty erosions can be associated with tophi of monosodium urate (MSU). These tophi may be seen invading the subchondral bone [10]. Synovial pannus tissue is not a typical feature of gout. Characteristics of bony erosion are outlined in Table 16.1.

Enthesitis (Fig. 16.4) Psoriatic arthritis, ankylosing spondylitis, inflammatory bowel disease (IBD)-associated arthritis, reactive arthritis, and undifferentiated spondyloarthritis belong to the spondyloarthritides, a family of conditions characterized by inflammatory erosive arthritis, new bone formation (in contrast to RA), as well as inflammation at the attachment points (entheses) of ligaments and tendons [11]. This inflammation at the entheses can be associated with new bone formation or calcification. This leads to bridging osteophytes, for example, in the case of ankylosing spondylitis. Enthesitis, one of the hallmark features of this group of diseases, can readily be

Table 16.1  Bony erosion characteristics

Joints most commonly effected

Synovial pannus tissue Other distinguishing features

Rheumatoid arthritis PIP MCP MTP Wrist Elbow Yes

Osteoarthritis DIP First CMC Shoulder Hip Knee Forefoot No

Marginal location (outer border)

Spur formation Centrally located erosion

Gout

No Tophi Marginal bony overhang

assessed sonographically [12]. Blood flow at the interface of tendon and bone (a normally avascular region) can be detected with Doppler ultrasound. Edema of tendon or ligament at and near origin or insertion appears sonographically as a loss of dense packing of parallel fibers, decreased echogenicity due to interfibrillar fluid-containing tissue, and an increased tendon thickness [13]. Effusion and synovial proliferation in associated synovial structures can be seen (e.g., the retrocalcaneal bursa in Achilles tendon enthesitis). Bony erosion outside of synovial joints can be seen at and near the enthesis (e.g., erosions of the posterior aspect of the calcaneus). Typically affected entheses include the common extensor tendon at the lateral epicondyle of the elbow, the origin of the patellar ligament at the distal pole of the patella, and the insertion of the Achilles tendon [14].

Crystal Arthritis (Fig. 16.5a, b) Gout is the most common form of inflammatory arthritis in men over 50 and postmenopausal women. It is characterized

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Fig. 16.4  Achilles tendon insertion, dorsal long-axis view. Enthesitis in psoriatic arthritis patient. Hyperemia of tendon near insertion into calcaneus is seen. Areas of neovascularization appear red orange under Doppler

by deposition of aggregates of MSU crystals in joints and soft tissues, in patients with long-standing hyperuricemia (levels of serum urate above solubility). These tophi are surrounded by a corona of inflammatory cells and are embedded in a matrix of fibrovascular tissue [15]. Contact of tophi and their surrounding inflammatory cells with adjacent bone leads to erosion formation. Chronic, low-degree (subclinical) inflammation can lead to joint deformity over time. If this equilibrium is disturbed (sudden increase in serum urate levels through diet, sudden drop in urate level through treatment, dehydration, trauma, etc.), inflammatory cells are attracted to MSU crystals or tophi, and a gout attack ensues. MSU crystals are strongly echogenic; they are seen as hypo- to hyperechoic aggregates of bright-appearing crystals [16]. The packing of MSU crystals in tophi allows through transmission of sound waves. Tissues deep to MSU tophi can be seen at frequencies that are used in musculoskeletal ultrasound. Typically, there is not a pronounced posterior acoustic shadow visible (occasionally, in very long-standing gout, tophi can become very dense or calcify, and lower frequencies are needed for assessment of structures deep to the tophi). On conventional radiographs, MSU tophi are usually not visible, but aggregates of calcium-containing crystals are. This can help distinguish gout from pseudogout due to calcium pyrophosphate dihydrate (CPPD) deposition. In joints, MSU tophi and CPPD crystals have different patterns of distribution. In gout, MSU crystals deposit on the outer surface of hyaline cartilage. Sonographically, this creates the appearance of a “double contour” [17]. The outline of the hyperechoic bony cortex is paralleled by a hyperechoic

layer of crystals, with anechoic to hypoechoic hyaline cartilage separating both. In contrast, CPPD crystals deposit in central lacunes of hyaline cartilage, so that a hyperechoic band of crystal is embedded in the anechoic- or hypoechoic-­ appearing hyaline cartilage. Similarly, calcium-containing crystals may appear in the center of fibrocartilage. Typical areas accessible to sonographic assessment include the posterior aspect of the glenoid labrum in the shoulder, the triangular fibrocartilage of the wrist, and the menisci of the knee.

Red Flags Synovitis Synovitis can have different meanings: simple joint effusion without synovial thickening, thickening of the synovial lining of a joint, and synovial hyperemia. While aspiration is appropriate for simple synovial effusions, synovial thickening and particularly pronounced synovial hyperemia seen on Doppler ultrasound are signs of inflammatory arthritis [18]. A referral to the rheumatologist for an evaluation of systemic inflammatory arthritis, including rheumatoid arthritis, would be appropriate in this setting.

Crystal Arthritis If typical hyperechoic, tophaceous material in or around joints and tendons is found sonographically, an evaluation

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a

b

Fig. 16.5 (a) Metacarpophalangeal joint, dorsal long-axis view. Doublecontour sign of gout. Hyperechoic crystalline deposits over anechoic hyaline cartilage and hyperechoic bony contour are seen between arrowheads. MC metacarpal head, PP proximal phalanx. (b) First metatarsophalan-

geal joint, dorsal long-axis view. Tophaceous gout. Hyperechoic tophaceous deposits distend the joint capsule (between arrowheads). ET extensor tendon, PP proximal phalanx

for gout, and subsequent treatment, is appropriate. The evaluation may include aspiration of tophaceous material. The aspirated material can be assessed in a qualified office or in the lab with polarizing microscopy for the presence of typical crystals.

when sound waves are reflected at the angle of perpendicular incidence off the surface of cartilage and can indicate a small effusion. This bright outline usually appears at the surface area of cartilage that is nearest to the transducer. In contrast to this, the rough surface deposits of urate crystals follow the contour of the bone over a wider area. The crystal deposits create multiple small surfaces that reflect the sound waves in all directions. The reflection of the “double-contour” sign is, therefore, less dependent on the transducer position.

Pearls and Pitfalls Gout: Double-Contour Versus Interface Reflex In gout, MSU (uric acid) crystal can precipitate on hyaline cartilage over bony surfaces in joints. This creates the sonographic appearance of a “double contour.” The hyperechoic, bright bony contour is covered by anechoic (or hypoechoic) dark hyaline cartilage. Bright, hyperechoic crystalline deposits form the second contour (superficial to the hyaline cartilage). This may be confounded with the bright, hyperechoic interface reflex over hyaline cartilage. This reflex is created

 ynovial Hyperemia: Artifact Versus Real S Signal Ultrasonography is particularly well suited to detect and characterize inflamed tissues [19]. Power Doppler or color Doppler signals can be seen in synovial tissues of patients who would otherwise be thought to be in clinical remission based on physical examination and serology [20]. As the

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gain on the Doppler mode increases, so does the area that “lights up” on the screen. Sensitivity and specificity of Doppler signals are improved if a few simple steps are followed. First, turn the Doppler setting to its maximal gain. Notice that the “Doppler box” will completely fill with signals. Then, decrease the gain until artifacts deep to the bony surface disappear. (Ultrasonography at frequencies used in musculoskeletal ultrasound cannot penetrate bone. Any signals that appear deep to the bony cortex are therefore by default artifacts.) Finally, adjust the Doppler box to cover just a small area being scanned. This will take up less computing power and provide faster image turnover. Then, identify suspicious areas (e.g., hypoechoic synovitis) in gray scale first. Try to match any Doppler signals with this area that was identified in gray scale. Making anatomic “sense” of your signals is one of the best protections against mistaking artifacts for actual blood flow. Look for consistent Doppler signals; disregard signals that appear and disappear randomly. Other sources of signals that can mimic synovitis are from blood vessels and probe or patient motion. If the Doppler signal is synchronous with the patient’s pulse, rotate the probe’s axis to help distinguish it from small blood vessels. Anchor your probe hand against the patient or other stable object, and “float” the probe atop the gel layer to avoid compression of vessels [13]. Use two hands, and position the patient on a stable surface to avoid motion artifacts.

Clinical Exercise In order to appreciate abnormalities in patients, it is very helpful to familiarize yourself with normal sonographic anatomy. The following exercises are recommended: 1. Identify anatomical structures in finger joints.

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(a) MCP joint from dorsal (Fig. 16.6). Place probe in the longitudinal or long axis over midline of MCP joint. Joint line should be in center of image on screen. Elongate the image so that the shaft of the metacarpal bone is seen on screen proximally and proximal phalanx distally. Make sure that bones do not run out of plane. Identify bony cortex of metacarpal shaft, anatomical neck, and metacarpal head. Pearl: The anatomic neck just proximal to the metacarpal head may be confused with a bony erosion. Erosions, however, are defined as breaks in the cortical contour. With “rocking” of the probe (i.e., proximal-distal tilt maneuver), the cortical floor of the anatomic neck can usually be seen. Identify bony cortex of proximal phalanx. Appreciate the anechoic or hypoechoic layer of hyaline cartilage over the metacarpal head. The smooth surface of cartilage can sometimes create an “interface reflex” at the angle of perpendicular incidence of the sound waves (i.e., at the portion of the cartilage that is closest to the transducer) if no beam steer is used. Overlying the anechoic to hypoechoic hyaline cartilage is the fibrous tissue of the joint capsule. Over the joint space of metacarpal head and proximal phalanx, the joint capsule extends into a fibrous triangle that fills the space between the bones. Fibrous tissue usually appears bright and hyperechoic. Due to anisotropy, this fibrous triangle may appear dark and anechoic. This could mimic a joint effusion. Try to overcome this anisotropy with rocking of the probe. Slightly adjust the angle of insonation. Creating the image of a bright triangle that fills the space between the bones will help confirm that no effusion is present. Lastly, identify the extensor tendons overlying the fibrous joint capsule. (b) MCP joint from volar (Fig. 16.7). From volar, place the probe in long axis along the metacarpal bone and

Fig. 16.6  Metacarpophalangeal joint, dorsal long-axis view. Normal findings. ET extensor tendon, cart arrowhead hyaline cartilage, asterisk triangular extension of joint capsule, MC metacarpal head, PP proximal phalanx

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Fig. 16.7 Metacarpophalangeal joint, volar long-axis view. Normal findings. A1 arrow A1 pulley, FDS flexor digitorum superficialis tendon, FDP flexor digitorum profundus tendon, arrowhead proximal volar joint recess, asterisk volar plate, MC metacarpal head, PP proximal phalanx

Fig. 16.8 Proximal interphalangeal joint, volar long-axis view. Normal findings. FT flexor tendon, arrowhead proximal volar recess of joint, asterisk volar plate, PP proximal phalanx, MP middle phalanx

proximal phalanx, so that the joint line is in the center of the image. Identify hyperechoic outlines of metacarpal head and proximal phalanx. Find the hyaline cartilage of the metacarpal head. The volar plate is a strong fibrous stabilizer of the joint capsule that helps prevent overextension of the fingers. Superficial to the hyperechoic, bright volar plate run the flexor tendons. The flexor tendons are bound down by the A1 pulley at the level of the metacarpal head. Identify the usually dark, anechoic-appearing A1 pulley superficial to the flexor tendons. Pearl: Tendons and metacarpal bone are not perfectly aligned. You can often show either tendons or bones across the screen from the volar aspect. (c) PIP joint from volar (Fig.  16.8). Align the probe’s long axis along tendons and bones from the volar aspect, with the PIP joint in the center of the screen. Identify the bony contour of proximal and middle

phalanx. Hyaline cartilage that lines the head of the proximal phalanx will appear anechoic or dark. The volar plate is a pronounced fibrous plate that overlies bones and cartilage and forms the joint capsule. It helps prevent overextension of PIP joints. Appreciate the tendons superficially to the volar plate. Pearl: Joint fluid is only seen deep to the volar plate. Fluid collections that are frequently seen superficial to the volar plate communicate with the tendon sheath, not the joint. 2 . Assess vascularity of pulp of fingertip with power or color Doppler (Fig. 16.9). Assessment of increased blood flow in tissues is critical for the sonographic assessment of inflammatory conditions. Distinguishing actual blood flow from artifacts may be somewhat challenging at first [13]. It is also helpful to be familiar with the Doppler capabilities of your machine. Doppler settings may be adjusted so that the sensitivity is high enough to detect

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Fig. 16.9  Volar long-axis view of fingertip. Power Doppler shows digital vessel. Areas of neovascularization appear red orange under Doppler. MP middle phalanx, DP distal phalanx

neovascularity or engorgement of smaller vessels in inflamed tissues without creating artifacts. The volar aspect of the fingertip has highly vascularized tissue, even in normal individuals. This tissue may help gauge the quality and settings of your color and power Doppler function. Place the probe over the volar aspect of your fingertip. Use very little pressure. This may be achieved by using a generous layer of gel between probe and finder, or by using light touch. Adjust the size of your Doppler box so that the pulp of your fingertip is covered, but not areas proximal or distal to it, and no significant room remains deep to the bone. With the right Doppler settings, a larger digital artery should be seen adjacent to the bony contour of the distal phalanx. Verify pulse synchronous flow to rule out artifacts. 3. Appreciate anisotropy of Achilles tendon insertion. Anisotropy occurs where sound waves meet highly reflective surfaces, particularly tendons that curve away from the transducer [13]. Sound waves may be reflected at an angle that does not allow complete detection by the transducer, creating the false image of “missing structures.” Typical examples include the biceps tendon, which can appear artificially “dark” if the tendon fibers are not aligned parallel to the transducer surface (footprint), and the Achilles tendon, whose most distal fibers curve down to meet the bony surface of the calcaneus. To practice recognition of anisotropy as an artifact, place the transducer over the distal Achilles tendon, so the tendon fibers of the main body of the tendon run parallel to the transducer footprint. The tendon fibers will appear bright, but a dark triangle may be seen at the distal attachment area. If the transducer angle is tilted down, with the distal portion moving more anterior to patient or model, the distal tendon fibers will again run more parallel to the transducer, and the anisotropy can be overcome.

References 1. Backhaus M, Burmester GR, Gerber T, et  al. Guidelines for musculoskeletal ultrasound in rheumatology. Ann Rheum Dis. 2001;60(7):641–9. 2. Moller I, Janta I, Backhaus M, et al. The 2017 EULAR standardized procedures for ultrasound imaging in rheumatology. Ann Rheum Dis. 2017;76(12):1974–9. 3. Mandl P, Balint PV, Brault Y, et al. Metrologic properties of ultrasound versus clinical evaluation of synovitis in rheumatoid arthritis: results of a multicenter, randomized study. Arthritis Rheum. 2012;64(4):1272–82. 4. Thiele RG.  Ultrasonography applications in diagnosis and management of early rheumatoid arthritis. Rheum Dis Clin N Am. 2012;38(2):259–75. 5. Schmidt WA, Schmidt H, Schicke B, et  al. Standard reference values for musculoskeletal ultrasonography. Ann Rheum Dis. 2004;63(8):988–94. 6. Wakefield RJ, Balint PV, Szkudlarek M, et  al. Musculoskeletal ultrasound including definitions for ultrasonographic pathology. J Rheumatol. 2005;32(12):2485–7. 7. Wakefield RJ, Balint PV, Szkudlarek M, et al.; OMERACT 7 Special Interest Group. Musculoskeletal ultrasound including definitions for ultrasonographic pathology. J Rheumatol. 2005;32(12)2485–7. 8. Wakefield RJ, Gibbon WW, Conaghan PG, et  al. The value of sonography in the detection of bone erosions in patients with rheumatoid arthritis: a comparison with conventional radiography. Arthritis Rheum. 2000;43(12):2762–70. 9. Zayat AS, Ellegaard K, Conaghan PG, et  al. The specificity of ultrasound-­detected bone erosions for rheumatoid arthritis. Ann Rheum Dis. 2015;74(5):897–903. 10. Schlesinger N, Thiele RG.  The pathogenesis of bone erosions in gouty arthritis. Ann Rheum Dis. 2010;69(11):1907–12. 11. D’Agostino MA, Said-Nahal R, Hacquard-Bouder C, et  al. Assessment of peripheral enthesitis in the spondylarthropathies by ultrasonography combined with power Doppler: a cross-sectional study. Arthritis Rheum. 2003;48(2):523–33. 12. McGonagle D, Lories RJ, Tan AL, et al. The concept of a “synovio-­ entheseal complex” and its implications for understanding joint inflammation and damage in psoriatic arthritis and beyond. Arthritis Rheum. 2007;56(8):2482–91.

246 13. Taljanovic MD, Melville DM, Scalcione LR, et  al. Artifacts in musculoskeletal ultrasonography. Semin Musculoskelet Radiol. 2014;18(1):3–11. 14. D’Agostino MA, Aegerter P, Jousse-Joulin S, et al. How to evaluate and improve the reliability of power Doppler ultrasonography for assessing enthesitis in spondyloarthritis. Arthritis Rheum. 2009;61(1):61–9. 15. Dalbeth N, Pool B, Gamble GD, et  al. Cellular characterization of the gouty tophus: a quantitative analysis. Arthritis Rheum. 2010;62(5):1549–56. 16. Thiele RG.  Role of ultrasound and other advanced imaging in the diagnosis and management of gout. Curr Rheumatol Rep. 2011;13(2):146–53.

R. G. Thiele et al. 17. Thiele RG, Schlesinger N.  Diagnosis of gout by ultrasound. Rheumatology (Oxford). 2007;46(7):1116–21. 18. D’Agostino MA, Terslev L, Aegerter P, et  al. Scoring ultrasound synovitis in rheumatoid arthritis: a EULAR-OMERACT ultrasound taskforce—Part 1: definition and development of a standardized consensus-based scoring system. RMD Open. 2017;3(1):e000428. 19. Thiele R. Doppler ultrasonography in rheumatology: adding color to the picture. J Rheumatol. 2008;35(1):8–10. 20. Brown AK, Quinn MA, Karim Z, et  al. Presence of significant synovitis in rheumatoid arthritis patients with disease-modifying antirheumatic drug-induced clinical remission: evidence from an imaging study may explain structural progression. Arthritis Rheum. 2006;54(12):3761–73.

Approach to Peripheral Nerves

17

Adam J. Susmarski

identify the course of a small-diameter nerve, e.g., Baxter’s nerve (first branch of the lateral plantar nerve), or to aid in visualization of the identified peripheral nerve and surrounding structures prior to and during an ultrasound-guided nerve block or hydrodissection. The measurement function on the ultrasound machine will also become of value during the diagnostic assessment for nerve entrapment which can be obtained using linear or straight-line measurement tools, as well as identification of the cross-sectional area with the ellipse or free-hand measurement tools depending on the peripheral nerve and body Probe Selection and Technique area. The cross-sectional measurement can be compared to standard measurements and/or compared to measurement In the assessment of peripheral nerves, most often a high-­ of the same nerve at a different location. The difference frequency (12–18  MHz) linear probe is recommended. between those two locations/measurements can determine While not required, a “hockey stick” probe’s smaller foot- if there is compression and/or swelling of the nerve. print may allow for ease of scan around bony prominences, Typically, nerves will become smaller as they travel dise.g., scanning the tibial nerve posterior to the bony promi- tally. See Fig. 17.2a, b. nence of the medial malleolus. If a hockey stick probe is not available, the challenge of bony prominences can be mediated with a linear probe by using a gel standoff technique. A Pearls and Pitfalls low-frequency (2–6 MHz) curvilinear probe may be beneficial when scanning specific structures in obese patients, Ensure that prior to measurement of the diameter or cross-­ patients with well-­developed musculature, or deeper posi- sectional area of a peripheral nerve the probe is positioned tioned peripheral nerves, e.g., proximal sciatic nerve. perpendicular to the nerve (short axis) to ensure the most Focal zones can be helpful in aiding in the scanning of the accurate measurement. The user should also aim to perform course of a nerve. The focal zone can often be adjusted with measurement at the area of maximal enlargement. There are a dial on the ultrasound machine to highlight a depth on the multiple resources that identify mean reference values for screen in which the peripheral nerve is located to improve each peripheral nerve in the upper and lower limb [1–3] the quality of the picture. This can be especially important to which can be used to identify enlargement; however, a more practical approach is identification of the affected area with a cross-sectional area 1.5 times larger than an unaffected area A. J. Susmarski (*) of the same nerve [4]. Medical Corps, United Sates Navy, United States Naval Academy, The reference values for nerves in the upper and lower Department Head Brigade Orthopedics and Sports Medicine, Annapolis, MD, USA limb are detailed in Tables 17.1 and 17.2 below. Peripheral nerves when visualized using ultrasound are typically described as having a “honeycomb” appearance when in short axis and a “train track” appearance when in long axis. There are some exceptions to this as the echotexture of the nerve can change based on the peripheral nerve being scanned and/or its anatomic location in which a more hypoechoic or hyperechoic appearance can be visualized and still be a normal finding. See Fig. 17.1a, b.

e-mail: [email protected]

© Springer Nature Switzerland AG 2021 J. M. Daniels, W. W. Dexter (eds.), Basics of Musculoskeletal Ultrasound, https://doi.org/10.1007/978-3-030-73906-5_17

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a

b

Fig. 17.1 (a) Median nerve in short axis. (b) Median nerve in long axis

a

b

Fig. 17.2 (a) Cross-sectional measurement of the median nerve at the inlet. (b) Cross-sectional measurement of the median nerve at the pronator quadratus Table 17.1  Reference values for cross-sectional area of nerves: upper limb Reference values for nerves in the upper limb Median nerve at the wrist Median nerve at forearm Median nerve at the elbow Ulnar nerve at Guyon’s canal Ulnar nerve at wrist Ulnar nerve at the forearm Ulnar nerve at the elbow Ulnar nerve at upper arm Radial nerve at upper arm

Bedewi et al. [2] 9.8 mm2 6.5 mm2 11.1 mm2 4 mm2 – 5.5 mm2 7.5 mm2 7.6 mm2 5.7 mm2

Qrimli et al. [3] 10 mm2 7.3 mm2 10.3 mm2 – 5 mm2 6.2 mm2 6.9 mm2 6.8 mm2 6.5 mm2

Table 17.2  Reference values for cross-sectional area of nerves: lower limb Reference values for nerves in the lower limb Tibial nerve at the popliteal fossa Tibial nerve at the level of the medial malleolus Common peroneal nerve at the popliteal fossa Common peroneal nerve at the fibular head Sural nerve Sural nerve at lateral malleolus

Bedewi et al. [1] Qrimli et al. [3] 19 mm2 – 12.7 mm2

12.7 mm2

9.5 mm2

11.8 mm2

8.9 mm2

11.1 mm2

3.5 mm2 –

– 2.1 mm2

17  Approach to Peripheral Nerves

Common Pathologic Conditions The most common finding on ultrasound in peripheral nerve entrapment is enlargement of the peripheral nerve proximal to the entrapment site. Additional findings may include enlargement of fascicles, changes in shape, increased hypoechoic echotexture, and increased vascularity within the nerve. See Fig. 17.3a–c.

Median Nerve Please reference Chap. 7 (Wrist) for detailed assessment and evaluation of median nerve entrapment at the wrist (carpal tunnel syndrome). Examples of median nerve pathology are included above.

Ulnar Nerve The ulnar nerve is most prone to injury (external compression and/or subluxation) at the area of the medial epicondyle and

a

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retrocondylar groove. However, proper evaluation of the ulnar nerve for areas of entrapment requires a detailed assessment of the length of the ulnar nerve. Additional entrapment areas of the ulnar nerve include the arcade of Struthers located in the proximal ulnar groove, the cubital tunnel which is distal to the medial epicondyle at the heads of the flexor carpi ulnaris where Osborne’s or the arcuate ligament is located between the origin of the two muscle heads (ulnar and humeral), and distally at Guyon’s canal at the wrist. See Fig. 17.4. The patient should be positioned supine, and the arm may be placed slightly abducted with a straight elbow or with the arm in 90 degrees of shoulder abduction and elbow flexion for evaluation of the ulnar nerve above and below the elbow. The preferred positioning is the latter with the arm in 90 degrees of shoulder abduction and elbow flexion to limit the amount of ulnar redundancy (similar to positioning for ulnar nerve CMAP during electrodiagnostic testing). The former is recommended with the arm slightly abducted, elbow in extension, and hand supinated for evaluation of the ulnar nerve at the wrist. The nerve should be viewed throughout its course in short and long axis. See Fig. 17.5a, b.

b

c Fig. 17.3 (a) Short-axis view of entrapped median nerve demonstrat- sectional area. (c) Long-axis view of the same nerve in the distal foreing increased cross-sectional area and enlarged fascicles. (b) Short-axis arm demonstrating proximal swelling and hypoechoic texture view of median nerve at pronator demonstrating increased cross-­

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As mentioned earlier in previous chapters, a benefit of point of care ultrasound is dynamic evaluation. In this setting, the ulnar nerve should undergo dynamic evaluation to evaluate for subluxation. A linear probe is placed between the medial epicondyle and the olecranon with the ulnar nerve visualized in short axis as the elbow is ranged through flexion and extension. In ulnar subluxation the nerve will be visualized moving medially and superficially over the medial epicondyle (Fig. 17.6a, b).

Pearls and Pitfalls Avoid excessive pressure with the transducer during this evaluation as the pressure of the probe may prevent subluxation of the ulnar nerve. The medial head of the triceps can aid in medial subluxation of the ulnar nerve over the medial epicondyle which can be demonstrated by asking the patient to contract the triceps muscle during dynamic evaluation.

Guyon’s canal

Radial Nerve The radial nerve is prone to injury and compression throughout its course starting proximally in the upper arm at the level of the spiral groove from fracture, compression from misuse of crutches, draping the arm over a chair/bench leading to common reference of “Saturday night palsy,” or repetitive use in overhead athletes. The radial nerve continues distally where it branches anterior to the lateral epicondyle into the posterior interosseous nerve (PIN) and the superficial radial nerve. The PIN innervates the supinator muscle prior to passing through the arcade of Frohse which is formed by the superficial and deep heads of the supinator. The superficial radial nerve (SRN) can be affected distally due to compression at the wrist from tight fitting bracelets or watches leading to its common reference as “handcuff neuropathy.” The patient should be positioned supine with the arm in shoulder abduction, externally rotated, and elbow flexion for evaluation of the radial nerve proximal to the elbow. The patient should be positioned supine with arm slightly abducted and hand supinated and resting on the table for evaluation of the radial nerve below the elbow. An alternative approach for evaluation below the elbow is to have the patient seated next to the exam table with the affected arm resting on the exam table with the hand pronated. See Fig.  17.7a–f for probe and patient position to track radial nerve around the elbow.

Ulnar nerve

Pearls and Pitfalls

Cubital tunnel (retrocondylar groove)

Fig. 17.4  Course of ulnar nerve and common entrapment site

a

Clinical symptoms and examination of the radial nerve can help narrow the focus of ultrasound investigation. Radial

b

Fig. 17.5 (a) Probe position to assess ulnar nerve at cubital tunnel. (b) Short-axis view of swollen (entrapped) ulnar nerve at cubital tunnel

17  Approach to Peripheral Nerves

a

b

Fig. 17.6 (a) Short axis view of ulnar nerve at retrocondylar groove (arrow). (b) Ulnar nerve subluxation (stars). Note that with same probe positioning as in (a) that when the ulnar nerve subluxates it will be visualized in a long axis viewpoint

n­ europathies in the upper arm will result in both motor and sensory findings distally in a radial nerve distribution as the level of entrapment or pathology is proximal to the nerve branching into the PIN and SRN. The PIN is a primarily motor nerve, and as a result injury to this nerve will demonstrate weakness (can be with or without lateral dorsal forearm pain) but will not have any sensory impairment as the SRN branches proximal to the arcade of Frohse. The SRN will create a sensory disturbance in the radial nerve distribution on the dorsum of the hand and distal forearm without motor weakness because the SRN branches proximal to the arcade of Frohse.

Fibular (Peroneal) Nerve The fibular nerve is most prone to injury at the fibular head. Proposed mechanisms include prolonged squatting and leg crossing, as well as compression from prolonged immobility or casting. The recommended patient positioning is lateral decubitus with the patient side lying on the unaffected leg and the affected leg (fibular head) toward the ceiling. The fibular nerve can also be evaluated in the prone and supine position. However, lateral decubitus positioning allows for optimization of scanning above and below the fibular head, as well as allows for comfort of positioning for the patient and the ability for the patient to be able to visualize the screen during scanning. Prone positioning can be potentially challenging and uncomfortable for the patient and also prevents visualization of the examination by the patient. Supine

251

positioning can make scanning above and below the fibular head challenging due to relation of the course of the nerve to the examination bed. The nerve should be viewed throughout its course in short and long axis from at minimum its branch from the sciatic nerve proximal to the fibular head in the popliteal fossa to its branch into the superficial and deep fibular nerves distal to the fibular head. See Fig. 17.8a, b.

Tibial Nerve The tibial nerve is most prone to entrapment in the tarsal tunnel as it passes posteriorly behind the medial malleolus underneath the flexor retinaculum. The recommended patient positioning is lateral decubitus with the patient side lying on the affected side allowing for the lateral malleolus of the affected leg to rest on the examination table and the medial malleolus of the affected leg toward the ceiling. The unaffected contralateral leg may be placed either anterior or posterior to the leg being evaluated based on patient preference and comfort. The nerve should be viewed throughout its course in short and long axis from at minimum proximal to its traversing of the flexor retinaculum at the tarsal tunnel and distal to the tarsal tunnel in which the tibial nerve will branch into the medial plantar, lateral plantar, and calcaneal branches. While evaluating the tibial nerve in the tarsal tunnel from anterior to posterior, the examiner will be able to identify the posterior tibialis tendon, flexor digitorum longus tendon, posterior tibial artery and veins, tibial nerve, and flexor hallucis longus tendon. See Fig. 17.9a, b. At approximately the distal portion of the tarsal tunnel, the tibial nerve will branch into the medial and lateral plantar branches. The medial plantar nerve initially dives deep to the abductor hallucis and travels through the abductor tunnel (a fibromuscular tunnel behind the navicular tuberosity) and more distally travels to the knot of Henry where the flexor digitorum longus and flexor hallucis longus cross. The lateral plantar nerve gives off its first branch to abductor digiti quinti and is also commonly referred to as Baxter’s nerve. The lateral plantar nerve continues to innervate the adductor hallucis and then distally moves laterally into the flexor digitorum brevis and quadratus plantae. See Fig. 17.9c.

Pearls and Pitfalls When evaluating the tibial nerve around the medial malleolus, a gel standoff technique will be required to limit artifact and improve visualization of the tibial nerve. An alternative approach is utilization of a hockey stick probe (when available) for this peripheral nerve evaluation as

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a

c

b

d Humerus Radial nerve

Superficial (sensory) branch radial n.

Extensor carpi longus

Posterior interosseous nerve Arcade of Frohse Supinatorsuperficial Supinator. deep

Extensor carpi brevis

Radius

Fig. 17.7 (a–c) Probe and patient position to track the radial nerve at the elbow: (a) Humeral shaft, (b) “home row,” and (c) proximal forearm at arcade of Frohse. (d) Illustration of course of radial nerve in the forearm.

Ulna

(e) Radial nerve seen at the “home row” of the elbow. (see probe position in (b)). (f) Screenshot of common site of impingement of radial nerve just distal to elbow at arcade of Frohse (see probe position (c))

17  Approach to Peripheral Nerves

e

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f

Fig. 17.7 (continued)

a

b

Fig. 17.8 (a) Common peroneal (or fibular) nerve, short axis, at fibular head. (b) Probe position to view peroneal (fibular) nerve at fibular head. The anatomy here is quite variable, so the examiner may need to adjust

the probe position to optimize this view. Consider using a “hockey stick” probe

this allows for a smaller footprint of the probe to avoid bony landmarks. The size of the medial plantar, lateral plantar, and calcaneal branches can be technically challenging due to their relative smaller size in comparison to the larger peripheral nerves discussed in this chapter. Additional clinical pearls that can help in the diagnosis of neuropathy include comparison to the contralateral asymptomatic side and potential edema or atrophy of the innervated musculature in the foot. Evaluation of distal branches of the tibial nerve including but not limited to the medial plantar nerve at the abductor tunnel (medial heel and arch pain), the medial plantar nerve at the knot of Henry (medial arch pain), and Baxter’s nerve (anterior-

medial heel pain) is recommended due to their potential mimicking of common musculoskeletal complaints.

Red Flags Peripheral nerves often run alongside vasculature structures. Identification and distinguishing between vascular and nerve anatomy can be challenging for even the most advanced ultrasonographer. Prior to and/or during interventional procedures, these structures should be correctly identified which can be enhanced with the use of power Doppler.

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b Fig. 17.9 (a) Screenshot of tibial nerve at the medial malleolus. (b) Proper patient positioning for evaluating the tibial nerve. Consider supporting the affected ankle with a pillow or bolster. (c) Screenshot of lateral and medial branches of the plantar nerve

References 1. Bedewi MA, Abodonya A, Kotb M, Kamal S, Mahmoud G, Aldossari K, Alqabbani A, Swify S. Estimation of ultrasound reference values for the lower limb peripheral nerves in adults: a cross-­ sectional study. Medicine (Baltimore). 2018;97(12):e0179. 2. Bedewi MA, Abodonya A, Kotb M, Mahmoud G, Kamal S, Alqabbani A, Alhariqi B, Alanazy MH, Aldossari K, Swify S,

Al-Bader F. Estimation of ultrasound reference values for the upper limb peripheral nerves in adults: A cross-sectional study. Medicine (Baltimore). 2017;96(50):e9306. 3 . Qrimli M, Ebadi H, Breiner A, et al. Reference values for ultrasonography of peripheral nerves. Muscle Nerve. 2016;53:538–44. 4. Hobson-Webb LD, Massey JM, Juel VC, Sanders DB. The ultrasonographic wrist-to-forearm median nerve area ratio in carpal tunnel syndrome. Clin Neurophysiol. 2008;119:1353–7.

17  Approach to Peripheral Nerves

Suggested Reading Bianchi S, Martinoli C.  Ultrasound of the musculoskeletal system. New York: Springer; 2007. European Society of Musculoskeletal Radiology. European Society of Musculoskeletal Radiology Guidelines. Essr.org. ESSR European Society of Musculoskeletal Radiology. Web July 2019.

255 Jacobson JA. Fundamentals of musculoskeletal ultrasound. Edition 2. Philadelphia: Saunders Elsevier; 2012. Malanga G, Mautner K.  Atlas of ultrasound guided musculoskeletal injections. China: McGraw-Hill Education; 2014. McNally E.  Practical musculoskeletal ultrasound. Second Edition. Philadelphia: Elsevier; 2014.

POCUS in Sports Medicine

18

Dae Hyoun (David) Jeong and Erica Miller-Spears

Introduction Physicians volunteering for sporting events are often called upon to treat acute trauma and musculoskeletal injuries on site. Imaging modalities are often not available and can lead to unnecessary transfers to the emergency room. Portable, low-cost ultrasound machines with good image quality are now available for clinicians to utilize. Point-of-care Ultrasound (POCUS) can be very useful at these events to make quick and accurate diagnoses. POCUS also aids in determining whether the athlete needs to be sent to a nearby hospital for further evaluation. Ultrasound (US) provides portable, high resolution, dynamic imaging without radiation. [1–4] Despite all these strengths, POCUS is still not universally accepted. Many clinicians hesitate to embrace POCUS. [2] Recent literature has demonstrated POCUS can be learned in a short amount of time by non-radiologists. [5–8] Medical clinics at recent Olympic and Paralympic games have utilized diagnostic ultrasound service on-site. [9, 10] Many team physicians and trainers utilize POCUS at the various venues. For example, World Taekwondo (WT), an official international federation of Olympic and Paralympic Taekwondo, has been officially utilizing POCUS at major competitions for the diagnosis and management of acutely injured athletes since the 2017 Muju World Taekwondo Championships in South Korea. In this chapter, the author will illustrate examples of POCUS used in the evaluation of acute sports trauma and illnesses which can be applied in many sporting event settings. D. Hyoun (David) Jeong (*) Sports and Musculoskeletal Medicine at SIU-FCM, World Taekwondo Medical and Anti-Doping Committee, SIU-SOM Affiliated Hospital, Family and Community Medicine, Springfield, IL, USA e-mail: [email protected] E. Miller-Spears Department of Family and Community Medicine Quincy, Southern Illinois University School of Medicine, Springfield, IL, USA

POCUS is useful for the detection of fractures, confirming joint dislocation, and evaluation of ligament, muscle, and tendon tears. Non-musculoskeletal indications include evaluation of ocular (e.g., traumatic vitreous hemorrhage or retinal detachment), thoracic (e.g., pericardial effusion, pneumothorax), abdominal (e.g., intra-abdominal organ rupture), and genital organ (e.g., testicular rupture) injuries. In addition, POCUS can be utilized to detect acute venous thrombosis (DVT) and monitor fluid status in the evaluation of dehydration or shock in athletes. [1–5, 8, 11, 12]

 reparation and Set Up of Portable P Ultrasound for POCUS at Sporting Events There are several types of portable machines available in the market. Laptop-type portable ultrasound machines are very popular. They can be setup in a venue medical area effortlessly and are easy to take in carry-on luggage when flying. These machines possess high enough resolution (quality of image) to rival the large, non-portable machines (see Fig. 18.1a). Handheld ultrasounds can be carried either in a side bag or backpack and connect to tablets or smartphones. Most handheld machines have the acceptable resolution for POCUS to evaluate injuries in acute trauma such as dislocation, displaced fracture, rupture or hematoma of soft tissue, intra-abdominal bleeding, and pneumothorax (see Fig. 18.1b).

Portable Machine Types The two most common transducers used for POCUS in sports medicine are linear (frequency 6-15 MHz) and curved-­ linear (2-5 MHz). The linear transducer is used for most scans in sports medicine for musculoskeletal (MSK) structures within 5cm of depth. It can also be used for US exam of ocular trauma, lung for pneumothorax, and genitals for tes-

© Springer Nature Switzerland AG 2021 J. M. Daniels, W. W. Dexter (eds.), Basics of Musculoskeletal Ultrasound, https://doi.org/10.1007/978-3-030-73906-5_18

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D. Hyoun (David) Jeong and E. Miller-Spears

b

Fig. 18.1  Portable laptop style ultrasound machine (a) Hand-held style portable machine to use with smart phone or tablet device (b)

ticular injuries. The curved-linear transducer is indicated for deeper MSK structures (posterior shoulder joint, hip joint, thigh, and buttock) as well as intra-abdominal organs, lungs, and heart (sub-xiphoid view). The phased array is helpful for cardiopulmonary evaluation in thoracic trauma due to its smaller footprint. This allows visualization of the cardiac windows between ribs. The curved linear probe can also be used in the evaluation of thoracic trauma.

from the athlete and legal guardian (in case of minor athletes) before performing the exam. A paper drape to cover an athlete to minimize unnecessary exposure may be helpful in some cases (see Fig. 18.2a and b). Machine Set up and Supplies

Machine Set Up and Supplies

Detection of the Fracture

The ultrasound machine should be set up on a stable surface such as table or desk with several comfortable chairs set up for the clinician and patient. Always make sure to prepare extra gel bottles. Putting gel in a couple of smaller tubes or bottles is very helpful to make it lighter weight to carry in a bag or pocket during the busy sporting events. Surgical lubricant is useful for ocular exam because it does not irritate eyes. A 4x4 Tegaderm may be used to protect the eyes from ultrasound gel. Paper towels to clean up gel from a body part, disinfection tissues to clean ultrasound machine, and transducers and disposable gloves should also be available. Ultrasound scanning should be done in a relatively quiet place that is cordoned off to protect the patient’s privacy. It is sometimes impossible to completely protect the privacy of patients during the ultrasound examination. In that case, clinicians performing the ultrasound must get a verbal consent

Acute fractures are very common in sports. Radiography is the first-line diagnostic imaging modality for fracture. However, radiography can sometimes miss occult fractures, especially in the acute phase. Computed tomography (CT) may confirm occult fractures; however, radiography is not readily available at sporting events. [13, 14] More information in addition to clinical findings is useful when making “return to play” decisions in real time. Advantages of POCUS for fracture in the pre-hospital setting could be triage, early reduction, and splinting, and selecting the best destination for treatment. [15] Studies comparing POCUS to radiography and CT scan demonstrated that POCUS has a high sensitivity and good diagnostic accuracy in the detection of the upper and lower limb bone and thoracic wall fractures in adults and pediatric populations. [14, 16–19] POCUS can also help identify frac-

 n-site POCUS for sports-related O musculoskeletal injuries

18  POCUS in Sports Medicine

a

259

b

Fig. 18.2  Performing POCUS (a) on a male Taekwondo athlete with left ankle injury at 2017 World Taekwondo Championships (Muju, South Korea). The ultrasound scans were done in a closed and quiet venue medical area with team staff and medical staff present. Ultrasound scan (b) of a left 5th finger on a Korean athlete with wireless handheld

ultrasound during 2018 World Taekwondo Grand Prix Final Championships (Fujairah, UAE). Note a small travel size shampoo container to carry ultrasound gel and disinfection cleaning sheets in the travel pack under the ultrasound gel container

ture characteristics such as the type, location, extension, angulation, stepping-off, and involvement of other structures adjacent to the bone. [14] A systematic review and subgroup meta-analysis conducted in 2019 which included 26 studies revealed that ultrasound (US) demonstrated good accuracy in the detection of upper and lower limb bone fractures in adults, especially in fractures of the foot and ankle. The pooled sensitivity and specificity of US were 0.93 and 0.92 for upper extremity fractures and 0.83 and 0.93 for lower extremity fractures. [17] Another study evaluated the diagnostic accuracy of US in 108 ED patients with 158 fractures in the extremities found the overall sensitivity was 68.3%, with sensitivity for femoral fractures and humeral fractures 100% and 76.2%, respectively. The detection of intra-­articular fractures had low sensitivity of 48%. [20] Thus, the literature suggests that the US can be considered as a first-­line imaging modality for the detection of fractures in the prehospital setting. Ultrasound of the bone fractures must show the disrupted or impaired cortical continuity in longitudinal and transverse scans to be considered diagnostic for certain fractures. Several studies have found that POCUS is able to determine cortical deformities more easily compared to radiography and ultrasounds sensitivity and specificity are high in determining fractures. [13, 14, 17] For the detection and diagnosis of long bone fractures with POCUS, “Kozaci Protocol” is available which takes about 2 minutes to complete eight steps (see Table 18.1). A clinician performing POCUS should scan the anterior, poste-

Table 18.1 Kozaci protocol for determination of fractures with POCUS [14] 1.  Presence of fractures (cortical disruption) 2. Type (fissure, linear, fragmented, spiral) and location of the fracture 3.  Angulation of the fracture 4.  Stepping-off distance of the fracture 5.  Extent of the fracture to the joint space (intra-articular fracture) 6.  Involvement in epiphyseal line 7.  Presence of adjacent bone fracture 8.  Presence of hematoma in the soft tissue and joint space Scanning the intact contralateral side recommended to confirm findings

rior, medial, and lateral surfaces of the bone, and from the proximal joint to the distal joint for long bones in both longitudinal and transverse planes. There are several types of bony irregularities that may mimic a fracture line which includes nutrient vessels, physeal plates, cortical erosions, posterior acoustic shadowing from sesamoid bones, ossicles or calcifications, postsurgical changes such as anchors, bone reshaping, partial excision, or hardware. It is very important for the clinician to take a good history and correlate findings with accompanying signs of injury. If there is no significant pain with palpation by US transducer or fingertip in the middle of US transducer footprint on the area of concern, it may not represent a bone injury [13] (see Figs. 18.3, 18.4, and 18.5).

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Fig. 18.3  A displaced ulnar shaft fracture of left forearm of a male athlete who blocked his opponent’s strong kick with his left forearm at 2017 World Taekwondo Championships (Muju, South Korea). The injured athlete presented with complaints of moderate pain, swelling, erythema, and crepitus on palpation on the ulnar side of distal left forearm. Fracture fragments (arrows) were identified with POCUS at venue and X-ray in the emergency room confirmed fracture. Note cortical dis-

ruption and step-off of the ulnar shaft on the longitudinal plane (a), transverse plane (b) and on AP view of X-ray of the left forearm (c). The venue medical doctor communicated with an orthopedic consultant at a designated tertiary medical center which facilitated the athlete being seen at the hospital fast track. The athlete underwent surgery on the same day of the injury

 ractures detected with portable US F machines

90 degrees to longitudinal position and short axis of the rib (see fig. 18.6b). The anterior margin of the costal cartilage and osseous rib is normally seen as a thin echogenic line. This line is usually continuous with a narrow discontinuity without a step-off often seen at the costochondral junction in healthy patients. The costal cartilage appears relatively hypoechoic compared with the osseous rib (see fig. 18.6c and d).

Displaced Ulnar shaft fracture of left forearm Left 5th proximal metacarpal fracture Comminuted right tibia shaft fracture

Rib fractures Rib fractures are one of the most common fractures in sports. It is the most common (25%) injury resulting from blunt chest trauma, which can often be missed on radiography. Rib fractures can result in serious complications such as pneumothorax, hemothorax, and pulmonary contusion. Ultrasound has been shown to be more sensitive in the detection of rib fractures and chondral rib fractures, compared with conventional radiography (78-90% vs 12 %). [21] The area of the rib that most tender on palpation should be evaluated with POCUS. This is accomplished by aligning the transducer in the transverse position parallel to the long axis of the rib (see fig. 18.6a). Scan is repeated by rotating probe

Rib Ultrasound A clear disruption of the anterior echogenic margin of the rib, costochondral junction, or costal cartilage on the scan is the key finding for the diagnosis of the rib fracture (see Fig. 18.7b). Subperiosteal hematomas can also be seen adjacent to the disruption site. There are some pitfalls to be aware of and avoid in rib ultrasound. The pleura has a similar sonographic appearance to the rib cortex, so the clinician should pay attention that the rib, not the pleura, is being examined. Pseudo-fractures can be falsely diagnosed if the transducer is placed over the rib

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Fig. 18.4  Left 5th proximal metacarpal fracture with intra-articular extension of a female Taekwondo athlete who sustained a kick to the dorsum of her hand during competition at 2017 World Taekwondo Championships (Muju, South Korea). The athlete complained of severe pain, tenderness, swelling, and limited range of motion of her wrist. POCUS was performed (a) and revealed cortical disruptions at proximal 5th metacarpal and carpo-metacarpal joint area with angulation in

longitudinal plane (b) and corresponding cortical disruption (void arrow) and associated hematoma (solid arrow) (c). Her team physician, a trauma orthopedic surgeon, agreed with athlete being placed in a fiberglass splint at the venue and she returned to Russia for further evaluation and treatment. A follow-up X-ray at an orthopedic trauma clinic when she returned home confirmed a proximal 5th metacarpal fracture of the left hand

and the intercostal space, or partly on the scapular blade and rib. If there is any doubt, a comparison scan with adjacent ribs on the same or opposite side and a relation of any abnormality being scanned should be performed to differentiate the fracture from the anatomical variant.

POCUS can be a reliable modality for the diagnosis of nasal fracture for adults and children. A retrospective study on 87 patients with nasal trauma comparing the use of high-­ resolution ultrasound (HRUS) to CT scan as an imaging modality for the diagnosis of the fracture in 2011 found that sensitivity and specificity of HRUS were 97% and 87% versus 100% and 72% in CT scan and 86% and 73% in conventional radiography. [22] Ultrasound has also been used to evaluate nasal cartilage. This can be useful in the intraoperative reduction of the fractured nasal bone. POCUS does have limitations in detecting other associated fractures of the facial bones in complex facial trauma. These injuries would require more advanced imaging at a tertiary center. Ultrasound scans of the nasal bone longitudinally and transversely, followed by oblique longitudinal scans of lateral walls of the nasal bone, are used to detect pathology (see fig. 18.8a–f). Cortical disruption of the nasal bone using

Rib fracture Nasal fracture Nasal bone fracture is one of the most common fractures in athletes with facial injury. It has been reported that radiographic evaluations were negative in 25% of patients with nasal bone fractures that required surgical intervention. [17] Physical examination without imaging study cannot determine the complexity of the nasal fracture and CT scan of head exposes the lens of the eye and brain to radiation.

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Fig. 18.5  Comminuted right tibia shaft fracture of a male para-­ Taekwondo athlete. The athlete had a strong shin-to-shin contact injury during the match at 2017 World Para Taekwondo Championships (London, United Kingdom). The athlete was not able to bear weight and had severe tenderness to light touch. POCUS on the right shin (a) and revealed two points of cortical disruptions which suggested commi-

nuted fracture of the right tibia shaft (b). Venue medical doctor reported the POCUS finding to an orthopedic consultant at nearby tertiary NHS medical center, allowing the athlete to be seen and managed by the consultant with minimal waiting time. X-ray at an NHS hospital confirmed the comminuted fracture (c). Athlete underwent surgery same day

POCUS is a positive finding for fracture. Presence of soft tissue edema and subperiosteal hematoma will assist in differentiating an acute from a chronic fracture. Nasal bone and cartilage ultrasound

be diagnosed by detecting the disruption of the fibers or the presence of a hematoma. [3] Tenosynovitis generates a hypoechoic or anechoic signal of distending fluid in the tendon sheath. Partial tears are detected by hypoechoic or anechoic focal defects within the tendon. Typical findings of a full-thickness tear are complete disruption of the tendon with retraction of the torn edges, which may be accompanied by a hematoma. Dynamic stress test of the tear will open a gap in the tendon. Tendinopathy (or tendinosis) refers to the natural degenerative disease of tendon caused by chronic use. Degenerative tendons show diffuse thickening, loss of fibrillar patterns, and calcification upon scanning. [3] Posterior tibialis tendon partial tear (see Fig. 18.9a–d) Ruptured 4th finger flexor digitorum profundus (Jersey Finger) (see Fig. 18.10a–d)

 etection of Other Acute Musculoskeletal D Injuries Tendon injuries Tendon injuries are also prevalant in sports. Most commonly injured tendons include the rotator cuff, Achilles, patellar, wrist extensor, and finger flexor tendons. On ultrasound, the tendon is normally seen as parallel fibrillar patterns of dense and hypo-dense signals on long axis. [2] Tendon injuries can

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Fig. 18.6  Demonstration of rib ultrasound and US findings of the normal rib. The patient is either supine position or sitting in a recliner. Use high-frequency linear transducer. Gently place the transducer on the injured area. Use copious gel to avoid unnecessary pressure on the fractured rib. Scan the area of interest in both longitudinal plane (a) and

transverse plane (b). Make sure to slide in all directions thoroughly to find any subtle cortical disruption and examine the adjacent ribs not to overlook any adjacent rib fractures. The cortex of the rib shows thin near-straight echogenic line in longitudinal plane (c) and thin arcuate-­ shaped echogenic line in transverse view (d)

Injuries of the rotator cuff tendons occur commonly in athletes from a wide variety of sports. One study evaluated 720 athletes with both ultrasound and MRI which revealed that 11.5% had partial-thickness rotator cuff tears. Of those athletes with tears, 66% of the articular-sided partial-­ thickness tears were overhead ball throwing athletes, and 75% of the bursal side partial thickness tears were body builders.[7] Supraspinatus and infraspinatus tendon injuries can result in both tendinosis and tears. Tendinosis is characterized by a

hypoechoic thickened tendon and may also demonstrate hyperemia on a power doppler. Tendon tears may be either partial thickness or full thickness. A partial-thickness tear may be categorized as articular (closest to joint), bursal (closest to bursa), or interstitial (in middle) area of the tendon. [3, 7] Athletes may also have asymptomatic rotator cuff tears, so the treatment should be based on a combination of clinical manifestations, physical examination, and imaging findings, not just imaging alone. [7]

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Fig. 18.7 (a) Male Taekwondo athlete who sustained a strong kick to the right flank complained of severe pain and tenderness to that area, 2017 World Taekwondo Championships (Muju, South Korea) POCUS performed on site and revealed 8th rib fracture of the right side of anterior thorax. See figure 18.6 for ultrasound probe placement. (b) Angulated and displaced rib fracture in the longitudinal plane. (c) Displaced rib fracture in transverse view (top arrow: superficial portion

Acute partial supraspinatus tear (see Fig. 18.11a–f)

Ligament injuries Ligament injuries are common in a variety of sports, especially involving ankle, knee, and finger ligament injuries. The anterior talofibular ligament (ATFL) is the most common injured ligament of the ankle in sports. Approximately two-thirds of ankle sprain cases are related to isolated ATFL injuries. ATFL injuries are caused by an inversion mechanism, most often in sports that involve running, jumping, cutting, or contact with other players, including soccer, basketball, football, volleyball, gymnastics, and cheerleading. [7]

of the fractured rib, bottom arrow: deeper portion of the fractured rib). Further chest ultrasound did not show any signs of pneumothorax and the athlete did not complain of dyspnea and vital signs were all stable. He was managed conservatively on site. He did receive follow-up care with his sports physician in his home country. His team physiotherapist reported the follow-up X-ray confirmed the rib fracture. He recovered in several weeks without any complications

Ultrasound (US) is a reliable and prompt modality for assessing ligament injuries and can delineate the type and degree of the injury accurately. A fast and accurate diagnosis of the injury is essential when prompt surgical management may be required. [3] US is an excellent imaging modality for ATFL injuries and has been shown to have a high specificity and sensitivity for evaluating both acute and chronic tears. [7] Ultrasound has demonstrated greater than 90% accuracy in identifying injuries to the ankle, including the ATFL. [7] Also, US is a good modality of choice for other ligament injuries of the ankle as well as other joints including the knee, elbow, and finger (see Figs. 18.12, 18.13, and 18.14) [1, 2, 23]. An acute ligament sprain is visualized on the ultrasound as ligamentous thickening, heterogeneity, and hypoechoic

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Fig. 18.8  Demonstration and normal appearance of nasal ultrasound. Use copious gel and apply very gentle pressure with caution to avoid any injury to eyes. Scan in the transverse plan on the nasal ridge (a) shows smooth arcuate-shaped cortical margin (arrow) (d). Then rotate

the probe in 90 degrees to make longitudinal plane (b), which shows echogenic line and junction with nasal cartilage (e). Then rotate 15 to 20 degree to make oblique longitudinal plane (c) which shows the echogenic line of lateral wall of the nasal bone (f)

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Fig. 18.8 (continued)

foci with surrounding edema. [3] Ultrasound can delineate different grades of ligament injuries, from grade I (microscopic tear) to grade III (rupture). In a grade I injury, the ­ligament may demonstrate normal structure on US but there is often adjacent fluid near the injured ligament. In grade II injury, US will show a thickened heterogeneous ligament with focal or diffuse areas of hypoechoic change with the loss of the typical fibrillar pattern, and with adjacent hypoechoic or anechoic fluid, but still continuity of the ligament is maintained. In a grade III injury, full-thickness tear with a discontinuity is identified on the US with associated hemorrhage or edema. Ultrasound may detect small avulsion fractures associated with ligament injuries as well, which manifest as an adjacent hyperechoic focal object with shadow (see fig. 18.14) [2, 7]. The presence of neovascularity around a ligament seen on US with color or power doppler can help differentiate between an acute and chronic injury. This can be very useful for patients with chronic joint instability due to previous ligament injuries of knee or ankle joint. [7] Dynamic test of the joint with stress (US-guided valgus or varus test for the knee and US-guided anterior drawer or talar tilt test for the ankle) can be used for real-time visualization of the instability of the joint and aid in grading the severity of the injury, which is not possible by MRI due to its static nature of obtaining images. [3, 7, 23] Acute ATFL sprain grade I Acute ATFL sprain grade II

Avulsion fracture and grade III tear of the UCL of L thumb (with Stener lesion)

Muscle Injuries Muscle trauma results from a wide range of mechanisms causing different types of injuries including contusions, strains, lacerations, compartment syndrome, or possibly hernias. Traumatic muscle injuries can be either extrinsic by external force or intrinsic by the eccentric mechanism of a given muscle. In extrinsic trauma, the lesion is usually located under the area of trauma. On the other hand, the intrinsic trauma usually causes an injury at the myotendinous junction which is the weakest portion of the muscle. Almost all types of muscle injuries can be visualized by POCUS.  On long-axis view, the normal skeletal muscle appears as hyperechoic linear band also referred to as “veins on a leaf” (see Fig. 18.15a and b). On short-axis view, the bundles of muscle appear as spot echoes with short, curvilinear, bright lines spread throughout the hypoechoic structure also referred to as “starry night” appearance (see Fig. 18.15c and d) [3]. Muscle strain is a common muscle injury which is usually caused by traction-type forces. US can differentiate the grade of severity of the strain. Low-grade strain may appear to be normal or hyperechoic on POCUS.  Partial tears cause disruption of muscle fibers and heterogeneous pattern of muscle

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Fig. 18.9  Posterior tibialis tendon partial tear in a male Taekwondo athlete who sprained his left ankle by eversion mechanism during 2017 World Taekwondo Championships (Muju, South Korea). Ultrasound of

the medial ankle showed a high-grade partial intrasubstance tear of the posterior tibialis tendon in the transverse plane (a and c) and longitudinal plane (b and d)

fibers adjacent to the myotendinous junction. A hematoma at the myotendinous junction is regarded as pathognomonic for a partial tear (see Fig. 18.16a and b). Complete tears appear as complete discontinuity of muscle fibers with associated hematoma, and retraction of the tendon ends can be seen. [3] Muscle contusion which is often accompanied by a hematoma results from direct non-penetrating trauma and most frequently seen in the thigh of athletes participating contact sports. On POCUS, a muscle contusion will present as an ill-defined hyperechoic area in the muscle which may cross the fascial planes. In contrast, a hematoma appears as a hypoechoic fluid collection and may contain debris. [3] As early as six hours after muscle injury, scans can demonstrate hematoma formation. The disruption of the muscle fibers will be seen directly by ultrasound, and dynamic stress can be used by contracting the muscle and observing for tis-

sue fibers to separate or pull apart. Liquefaction of the hematoma will show areas of low echogenicity and movement can be seen within the liquid on dynamic stress of the area with hematoma. [2] In the first 24 hours following injury, the appearance of the focal hematoma on ultrasound may change from hyperechoic to anechoic or hypoechoic. Ultrasound findings will become more hypoechoic or anechoic over the next two to three days. Thus, ultrasound evaluation of the small focal lesions should be performed in this period to better delineate the injury. As time passes, the hematoma generates increased echogenicity with possible fluid-fluid levels on POCUS examination. Weeks after the injury, it will become more organized and can develop a focal scar. Scarring of the muscle is easily seen with ultrasound as loss of the normal fibrillary pattern and an area of hyperechoic change in an

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Fig. 18.10  Rupture of right 4th flexor digitorum profundus (Jersey Finger) of a female athlete who had a hyperextension injury of the right 4th finger by opponent’s kick during 2017 World Taekwondo Championships (Muju, South Korea). Longitudinal plane (a and c) of the ventral 4th finger reveals anechoic signal (open arrow) in the middle phalanx which suggests rupture and retraction of the flexor digitorum profundus tendon (solid arrow). Transverse view (b and d) confirms tear

(open arrow). Note echogenic flexor tendon complex at proximal interphalangeal (PIP) joint and hematoma around tendon (a solid arrows respectively). The athlete was planning to return to her home country in 2 days, so finger splint was applied and she was advised to see a hand specialist in her country within 5 days (urgent evaluation) from the injury date to avoid any serious long-term complications

established scar. Muscle scarring is not well visualized on MRI scans. If the liquefying hematoma does not become smaller and there is no interval repeat injury, an MRI should be considered to rule out the possibility of a tumor. Myositis ossificans can be detected in its early phases with ultrasound as a hyperechoic area with acoustic shadowing occurs. Usually, patients with myositis ossificans feel that the region of the muscle tear has become larger and firmer. If any doubt and US is not conclusive, clinician should consider X-ray or CT scan for further evaluation for myositis ossificans. [2] Gastronemius muscle scan and normal tissue appearance High grade tear of gastrocnemius muscle at the myotendinous junction.

Small tear of biceps muscle and hematoma formation (see Fig. 18.17)

Dislocation Shoulder dislocations are a relatively common injury both in the general population and athletic population (especially sports requiring overhead motion). Dislocations affect 1.7% of the general population, resulting in 200,000 ED visits each year in the US, and comprise almost half the cases of all joint dislocations. [24] Most shoulder dislocations are reduced in the ED after confirmation with plain radiographs and repeat radiographs performed post reduction. More ­providers are now using ultrasound to assist in the treatment

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Fig. 18.11  Acute partial supraspinatus tear in a female athlete which she sustained during training. The athlete heard a pop and had severe pain and decreased abduction motion of the right shoulder on the first day of 2017 World Taekwondo Championships (Muju, Korea). The athlete was evaluated with US first with a subacromial view (a and d) which showed an insertional supraspinatus tear (solid arrows), then in a

f

longitudinal plane with modified Crass view (b and e), and finally rotator cuff interval view (c and f). Also present is a proximal bursal surface tear (stars) also referred to as a high-grade partial tear associated with an enlargement of the subacromial bursa (open arrow). After discussion regarding ultrasound findings, she withdrew from the competition to avoid further injuries

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Fig. 18.12  Acute ATFL sprain grade I. A male Taekwondo athlete sustained a twisting injury to his right ankle during 2019 World Taekwondo Championships (Manchester, UK). The athlete was able to weight bear on his right foot with moderate pain but he had severe tenderness to

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palpation on the anterior portion of the lateral malleolus. Ottawa ankle rules were negative. Ultrasound of the lateral ankle (a) revealed low-­ grade partial tear of the ATFL (b) with minimal laxity compared with intact contralateral ankle. Athlete treated with lace up ankle brace

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Fig. 18.13  A female athlete sustained a twisting injury to her left ankle during 2019 World Taekwondo Pan American President Cup (Las Vegas, USA). The patient was able to weight bear with severe pain. Physical exam revealed severe tenderness lateral ankle. Ultrasound

exam (a) revealed high-grade tear of the ATFL (b) and dynamic anterior drawer test showed moderate laxity. Athlete treated with bracing and crutches and received further care with her sports physician

and management of shoulder injuries as it can identify dislocation and confirm reduction. Ultrasound examination for shoulder dislocations and reductions can reduce time, cost, and exposure to radiation. A systematic literature review to compare the accuracy of ultrasound in comparison to X-ray in the assessment of shoulder dislocations found that all the studies in the review

had shown a specificity of 100% and most of the studies revealed sensitivity of 100% for identifying dislocations. Most of the studies have investigated the usefulness of the ultrasound for anterior shoulder dislocations. [24] The curvilinear transducer (or a deep probe setting) is generally used for detecting shoulder dislocation. The probe should be positioned over the scapular spine on the posterior

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Fig. 18.14  A female athlete was kicked and sustained an injury to the right thumb. A hyperextension injury was suspected. Ultrasound evaluation (a) revealed complete tear (b) of the UCL (solid arrow) with avulsion (arrowhead), part of the torn ligament stump placed on the joint

space (white arrowhead), and the remaining portion of the ligament retracted (open arrow). The athlete was treated with a thumb spica splint and instructed to see a hand specialist in Turkey within a week

shoulder in the transverse plan. Then, the transducer is moved laterally to visualize the glenoid and humeral head. If the humeral head is immediately adjacent to the glenoid, then it is in the normal anatomical position. If the humeral head is located above the glenoid on ultrasound, then the shoulder is posteriorly dislocated. If the humeral head is below the glenoid in the deeper in the ultrasound image screen, then the shoulder is anteriorly dislocated (see Fig. 18.18). Anterior shoulder dislocation

nerable to thermal and mechanical hazard. The “small parts preset” can be used as an alternative. On the scanner, Doppler should never be used when using ultrasound on the eye. The depth should be adequately adjusted to visualize the entire globe and distal part of the optic nerve. Also, adequate gain control is essential to visualize a hypoechoic posterior chamber. Otherwise, the clinician might overcall pathology with too much gain or miss subtle pathology with too low gain. For POCUS in ocular trauma, a high frequency (7.5MHz to 10MHz or higher frequency range) linear transducer with a small footprint is selected to match with the eye socket size. Sterile gel is not necessary for an ocular ultrasound exam but is highly recommended as it is less irritating to the eye. Otherwise, a piece of Tegaderm can be placed to the closed eyelid before applying the gel. Copious amounts of ultrasound gel should be applied to cover the entire eyelid after the eyes are closed. This allows the clinician to float the probe in the gel and avoid any unnecessary pressure to the globe which could cause discomfort or potential harm to the eye. Scanning in both transverse view and longitudinal view is required. While scanning, sweep the transducer up and down in the transverse view and side to side in the longitudinal view, to visualize the entire globe. Also, ask the patient to move his or her eyes slowly up and down and side to side in all four directions with the eyelid closed for dynamic scan. (see Fig. 18.19). Ocular Ultrasound Sonographic findings of the common eye pathologies (see Figure 18.20A-D) Traumatic Vitreous Hemorrhage (see Figure 18.21)

 . POCUS for sports-related non-­ 5 musculoskeletal injuries Ocular Ultrasound in acute ocular trauma The use of POCUS in the ED, prehospital, and various outpatient settings has been widely adopted in recent years to include ocular ultrasound. Ocular ultrasound is technically simple and easy to perform. Ocular ultrasound can show retinal hemorrhage (RH), vitreous hemorrhage (VH), retinal detachment (RD), vitreous detachment (VD), foreign bodies, lens dislocation, hyphema, globe rupture, retrobulbar hematoma, increased intracranial pressure (ICP), neoplasm and vascular disease, or ocular infections. [25, 26] It is preferred that trauma patients lay in a supine position due to potential spine trauma. Otherwise, a sitting position can be allowed. For the safety of retina, ophthalmic setting or preset should be selected (if available) because the eye is vul-

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Fig. 18.15  Normal appearance gastrocnemius or calf muscle. Myotendinous junction longitudinal axis (a and b) and transverse axis (c and d)

 bdominal and Thoracic Blunt Trauma by A eFAST (Extended Focused Assessment with Sonography in Trauma) Ultrasound may have an important role in the prehospital evaluation of athletes with thoracoabdominal trauma. “eFAST” has been widely used in prehospital and emergency medicine settings which has been validated for real-time assessment and triage of hemodynamically unstable patients by abdominal or thoracic trauma. It is a core component of Advanced Trauma Life Support algorithms (ATLS). [27]

The use of ultrasound in the setting of blunt thoracoabdominal trauma became widespread with the development of Focused Assessment with Sonography in Trauma (FAST) in 1995, which is a rapid 4-view examination for hemoperitoneum (hepatorenal recess, peri splenic area, recto vesicular) and hemopericardium or pericardial window. [11, 27, 28] Ultrasound can identify as little as approximately 200 mL of intraperitoneal free fluid with the sensitivity and specificity range from 42% to 98% and from 95% to 100%, respectively. [11] A new addition to the protocol resulted in eFAST, “e” stands for extended. This protocol adds to the FAST with

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Fig. 18.16  A male athlete heard a loud pop and developed pain in his right calf during 2017 World Taekwondo Championships (Muju, South Korea). Ultrasound of his calf revealed high-grade tear of gastrocnemius muscle at the myotendinous junction filled with hematoma

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(arrows) in the longitudinal plane (a) and transverse plane (b) which was compressible on the ultrasound. Athlete was still functional, despite findings on US, and was able to continue in the competition

The sensitivity and specificity for pneumothorax with US are 86% to 98% and 97% to 100%, respectively, whereas the same for supine anteroposterior chest X-ray are 28% to 75% and 99% to 100%, respectively. [11] The eFAST examination can be used to evaluate athletes with suspected thoracoabdominal trauma to improve the triage process. Sports-related thoracoabdominal trauma (pneumothorax, kidney, spleen, or liver injury or pericardial effusion) can be identified by ultrasound (see Fig. 18.22). eFAST Protocol

Pneumothorax Fig. 18.17  A male athlete who got a side kick on his left biceps during 2018 World Taekwondo Grand Prix championship (Moscow, Russia) complaining of severe pain and swelling in his arm. POCUS on his biceps muscle was performed which revealed hematoma from muscle tear in his biceps muscle. RICE (rest, ice, compression, elevation) was recommended. Repeated POCUS in 12 hours showed stable size of the hematoma and the pain was tolerable with RICE. Symptoms eventually resolved in a couple of weeks

further evaluation for a pneumothorax or hemothorax in addition to the abdominal and pelvic views (see Table 18.2).

Detecting pneumothorax with POCUS is quite easy, fast, safe which requires minimal training but yields high diagnostic accuracy. [27, 29] POCUS has the advantage of dynamic and repeated examinations compared to static imaging modalities such as plain radiograph or CT scan. [20, 27] The detection of pneumothorax by US in the prehospital setting will significantly influence the decision of clinicians to perform a tube thoracostomy or transfer to ER immediately. According to a study that evaluated prehospital chest ultrasounds in 281 patients, the acute medical management plan

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Fig. 18.18  A male junior athlete fell on his right shoulder during 2018 World Taekwondo Junior Championships (Hammamet, Tunisia) and was found to have extremely limited range of motion of right shoulder and severe pain and had a suspected dislocation. Pre-reduction ultrasound (a) of the right shoulder revealed noticible gap between humeral head (solid arrow) and glenoid (open arrow) which suggests anterior

dislocation. Shoulder reduction was performed and post-reduction ultrasound (b) confirmed the reduced shoulder joint with normal alignment of Glenohumeral joint (solid arrow: humeral head, open arrow: glenoid). The athlete demonstrated good range of motion in his right shoulder and his pain decreased significantly. Placement of US probe on posterior shoulder for evaluation (c)

changed in 21% by using ultrasound. It was determined to not insert a chest tube in 4% of those evaluated and at the destination of transportation another 4% were not inserted. [20] A pneumothorax is characterized by the absence of lung sliding and B-line pattern with the dominant A-lines on US.  Lung sliding is the representation of the visceral and parietal pleura sliding against each other during respiration.

A-lines are horizontal reflections of the pleural line caused by gas below the parietal pleura either within or outside of the lung. B-lines are generated by the accumulation of fluid in the pulmonary interstitium. Thus, the confirmation of B-lines on POCUS of the lung reliably rules out a pneumothorax (see Fig. 18.23). Lung scan for pneumothorax

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Fig. 18.19 (a) Copious gel applied on a 4x4cm sized Tegaderm covering the closed eye and applying copious gel. (b) Transverse scanning. Instruct patient to move the eyes from side to side and up and down as needed. (c) Longitudinal scanning. Instruct patient to move the eyes

from side to side and up and down as needed. (d) Normal appearance of the eye. Pupil (white arrow), lens (open arrow) are well visualized. Round anechoic globe (solid arrowhead). Part of hypoechoic optic nerve is seen. (open arrowhead)

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b

d

Fig. 18.20 (a) Foreign body (white arrow) seen on ultrasound as bright hyperechoic focal signal. (b) Global rupture. Heterogenous irregular signal change in the globe is observed on the ultrasound. (c)

Lens dislocation which is usually caused by trauma. Dislocated lens sits on the bottom of globe. (d) Retinal detachment. Squiggly line through the middle of the globe

18  POCUS in Sports Medicine

277 Table 18.2  Protocol eFAST (Extended Focused Assessment with Sonography in Trauma) Probe location, description 1. Right upper quadrant Probe placed at posterior mid-axillary line on right in longitudinal position 2. Anterior thoracic Probe placed on most anterior aspect of chest in longitudinal position

Fig. 18.21  A female athlete kicked in her left eye by an opponent during 2017 World Taekwondo Championships (Muju, South Korea) complained of shaky vision with eye movement and eye pain. POCUS of the left eye revealed vitreous hemorrhage without lens subluxation or globe rupture. As the athlete moved her eyes from side to side, heterogenous smooth appearance hemorrhage (white arrow) was swirling structure in the globe with patient’s eye movement on ultrasound. The athlete was transferred to tertiary medical center for ophthalmology consultation, who confirmed vitreous hemorrhage

Structures assessed / pathology Hepatorenal recess (Morison’s pouch) for abdominal free fluid Slide cranially to evaluate for right-sided pleural effusion Evaluate for lung sliding at several rib spaces Evaluate left and right lung for pneumothorax (no lung sliding) M mode may be used for pleural motion Four chamber view 3. Subcostal view Evaluate for pericardial effusion or Probe placed at subcostal pericardial tamponade area in transverse position Evaluate splenorenal space for 4. Left upper quadrant abdominal free fluid Probe placed at posterior Slide cranially to evaluate for mid-axillary line on left in left-sided pleural effusion longitudinal position Evaluate rectovesical or rectouterine 5. Pelvis pouch for free fluid or hemorrhage Probe placed low in pelvis in transverse position, point between bladder and either prostate (male) or uterus (female) toward pubic bone Rotate probe to longitudinal Sweep inferior to superior and left to position, point toward pubic right to view space bone

a

Fig. 18.22 (a) Subcostal view: evaluates for pericardial effusion. (b) RUQ: Hepatorenal recess (Morison’s pouch): evaluates for hemorrhage between liver and right kidney and/or hemothorax. (c) LUQ: Splenorenal recess evaluates for hemorrhage between spleen and left kidney and/or

hemothorax. (d) Pelvis: Rectovesical pouch (male) or rectouterine pouch (female): evaluates for hemorrhage between bladder and prostate (or uterus). (e) Lung, bilateral: evaluates for pneumothorax in left and/ or right lung; M mode to evaluate for pleural motion

278

b

c

d

Fig. 18.22 (continued)

D. Hyoun (David) Jeong and E. Miller-Spears

18  POCUS in Sports Medicine

e

Fig. 18.22 (continued)

279

280

D. Hyoun (David) Jeong and E. Miller-Spears

a

c

Fig. 18.23 (a) Linear or curved linear transducer placed on 2nd intercostal space. Perform scan bilaterally. (b) Pleural line (arrow), evaluate for lung sliding (flickering or ants marching at pleural line during respirations) if absent could indicate pneumothorax. (c) M Mode of the lung

b

d

without pneumothorax shows seashore sign (sky, ocean, and beach sign) with pleural motion. (d) M Mode of the lung with pneumothorax shows bar code sign (stratosphere sign), no pleural motion

18  POCUS in Sports Medicine

References 1. Sconfienza, et  al. Clinical indications for musculoskeletal ultrasound updated in 2017 by European Society of Musculoskeletal Radiology (ESSR) consensus, Sconfienza et  al. Eur Radiol. 2018;28:5338–51. 2. The use of ultrasound in athletes. GM All. Eur J Radiol. 109(2018):136–41. 3. Tok, et  al. Musculoskeletal ultrasound for sports injuries. Eur J Phys Rehabil Med. 2012;48:651–63. 4. Prehospital ultrasound in the management of trauma patients: Systematic review of the literature. 5. Point-of-care ultrasound with pocket-size devices in emergency department. Mancusi et al. Echocardiography. 2019;36:1755–64. 6. Lau, et al. Use of pocket-sized ultrasound device in the diagnosis of shoulder pathology. Clin J Sport Med. 2020;30:20–4. 7. Spicer, et  al. Ultrasound in sports medicine. Radiol Clin N Am. 57(2019):649–56. 8. Saranteas T, et  al. Ultrasonography in trauma: physics, practice, and training. JBJS Reviews. 2018;6(4):e12. 9. Crema, et  al. Imaging-detected acute muscle injuries in athletes participating in the Rio de Janeiro 2016 Summer Olympic Gems. Br J Sports Med. 2018;52:460–4. 10. Sports Injuries at the Rio de Janeiro 2016 Summer Olympics: Use of Diagnostic Imaging Services. Radiology. 287(3):922–32. 11. Finnoff, et  al. Sports Ultrasound: Applications Beyond the Musculoskeletal System. Sports Health. 2016;8(5):412–7. 12. Abdolrazaghnejad, et  al. Ultrasonography in emergency department: a diagnostic tool for better examination and decision-making. Adv J Emerg Med. 2018;2(1):e7. 13. Hoffman DF, et al. Ultrasonography of fractures in sports medicine. Br J Sports Med. 2015;49:152–60. 14. Avci, et  al. Comparison of point-of-care ultrasonography and radiography in the diagnosis of long-bone fractures. Medicina. 2019;55:355. 15. Chen L, et  al. Diagnosis and guided reduction of forearm fractures in children using bedside ultrasound. Pediatric Emerg Care. 2007;23(8):528–31.

281 16. Caroselli, et al. A pilot prospective study to validate point-of-care ultrasound in comparison to x-ray examination in detecting fractures. Ultrasound in Med & Biol. 2020;46(1):11–9. 17. Champagne, et al. The effectiveness of ultrasound in the detection of fractures in adults with suspected upper or lower limb injury: a systematic review and subgroup meta-analysis. BMC Emerg Med. 2019;19:17. 18. Ko C, et  al. The diagnostic accuracy of ultrasound in detecting distal radius fractures in a pediatric population, Clin J Sport Med 2019;29:426–429 19. Zhao W, et al. The value of ultrasound for detecting hand fractures. Medicine 2019;98:44 (e17823). 20. Ketelaars, et al. ABCDE of prehospital ultrasonography: a narrative review. Crit Ultrasound J. 2018;10:17. 21. Turk F, et  al. Evaluation by ultrasound of traumatic rib fractures missed by radiography. Emerg Radiol. 2010;17:473–7. 22. Mohammadi and Ghasemi-Rad. Nasal bone fracture  – ultra sonography or computed tomography? Med Ultrasonography. 2011;13(4):292–5. 23. Baloch, et  al. “Sports Ultrasound”, advantages, indications, and limitations in upper and lower limbs musculoskeletal disorders. Review article. Int J Surg. 2018;54:333–40. 24. Gottlieb, et  al. Diagnostic accuracy of ultrasound for identifying shoulder dislocations and reductions: a systematic review of the literature. Wes J Emer Med. 2017;8(5) 25. Kilker, et  al. Bedside ocular ultrasound in the emergency department. Eur J Emerg Med. 2014;21:246–53. 26. Roque, et  al. Bedside ocular ultrasound. Crit Care Clin. 2014;30:227–41. 27. El Zahran, El Sayed. Prehospital ultrasound in trauma: a review of current and potential future clinical applications. J Emerg Trauma Shock. 2018;11(1):4–9. 28. Gleeson T, Blehar D.  Point-of-care ultrasound in trauma. Semin Ultrasound CT MRI. 2018;39:374–83. 29. Krogh, et  al. Effect of ultrasound training of physicians working in the prehospital setting. Scandinavian J Trauma Resuscita Emerg Med. 2016;24:99.

Index

A Abdominal and thoracic blunt trauma by extended focused assessment with sonography in trauma, 272–273 Accreditation, 3, 5–6 Achilles tendon, 22, 136 insertion, 241, 245 and retrocalcaneal bursa, 133 Acoustic enhancement, 21 Acoustic shadowing, 19, 21 Acromioclavicular (AC) joint, 220, 221 Acromioclavicular joint with arthropathy, 97 Acute ATFL sprain grade I, 266 male Taekwondo athlete, 270 Acute ATFL sprain, Grade II, 266 Acute partial supraspinatus tear, 264, 269 Adductors, 197 Adhesive Capsulitis, 97 Advanced ultrasound techniques, 24 AIUM practice accreditation, 4–5 Anisotropy, 19, 50, 245 Ankle, 131 Ankle joint, 131 anatomic structures, 137 anisotropy in tendons, 137 anterior, 131–132, 134 common injuries/musculoskeletal disorders, 131 complete tendon ruptures, 136 lateral, 140–143 lateral quadrant, 133 medial, 139 medial tendon group, 132 posterior, 144 posterior quadrant, 133 ultrasound of, 136 Ankle tendon sheath injection, 232–233 Ankylosing spondylitis, 240 Annotation features, 9 Annular pulley tear/Climber’s finger, 29 Anterior elbow, 75 Anterior hip, 169–178 musculature, 198 Anterior knee, 147–148 Anterior recess assessment, 91 Anterior shoulder, 100, 103–111 anatomy, 100 dislocation, 271 A1 Pulley Thickening/Trigger Finger, 44 Articular cartilage, 24, 25 Articular surfaces of diarthrodial joints, 215 Autogain feature, 12 Avulsion fracture and grade III tear of the UCL of L thumb (with Stener lesion), 266

B Baker’s cyst, 166, 231 Biceps femoris, 149 Biceps tendonitis/tenosynovitis, 97 Biceps tendon subluxation, 97 Blockade of the suprascapular nerve at the suprascapular notch, 222 B-mode (brightness mode) ultrasound, 11 Bony erosion, 239–240 characteristics, 240 Bursae, 24, 25 C Calcification in infraspinatus, 96 Calcific tendonitis, 96–97 Carpal tunnel syndrome (CTS), 225 on US, 52 Case study submission requirements for AIUM Certification, 5 Central slip tear/Boutonniere deformity, 29 Certification, 3, 5–6 Chronic repetitive movement of finger, 44 Clinical ultrasonography, 1 Collateral ligament tear/Gamekeeper’s thumb, 44–45 Color Doppler mode, 11 Comminuted right tibia shaft fracture, 260, 262 Complete-thickness rotator cuff tear, 96 Console systems, 7 Copious gel, 275 Cortical bone, 23, 24 Coupling of probe to skin, 18 Cross-sectional anatomy of wrist, 52 Crystal arthritis, 240–242 Cubital instability, 92 Cubital tunnel, distal approach, 224 Cubital tunnel syndrome, 92, 223–224 D Depth, sound wave, 12 De Quervain’s Tenosynovitis, 53 Direct inguinal hernia, 208–211 Displaced rib fracture in transverse view, 264 Displaced ulnar shaft fracture of left forearm, 260 of male athlete, 260 Distal bicep pathology, 91 Distal triceps tendon injury, 92 Docking cart, 7 Doppler effect, 11 Dupuytren contracture, 44 Dynamic test of joint with stress, 266 Dynamic views, 25

© Springer Nature Switzerland AG 2021 J. M. Daniels, W. W. Dexter (eds.), Basics of Musculoskeletal Ultrasound, https://doi.org/10.1007/978-3-030-73906-5

283

284 E Edge shadowing, 21 Elbow, 78–88 anterior structures, 76 deep structures, 91 medial ligaments, 90 posterior structures, 91 Enthesitis, 240 Extensor avulsion fracture/Mallet finger, 28–29 Extensor tendon tear, 28–29 External snapping hip, 195, 202–205 F Fascia, 22, 23 Fibularis longus and brevis tendon sheaths, 233 Fibular (Peroneal) nerve, 251 First CMC joint arthritis, 44 First dorsal compartment, 226 First tarsometatarsal joint, 234 Flexor digitorum superficialis and/or flexor digitorum profundus, 29 Fluid collection/bursal distension, 167 Focal zones, 12, 247 Focusing/Knobology, 19 Foot and toes, 117–128 interdigital neuroma, 117 linear transducer, 117 pathologic conditions, 117 posteromedial approach, 117 subtalar joint injection, 117 Foreign bodies, 45, 276 Fracture, detection, 258–260 with portable US machines, 260 G Ganglion cysts, 45 Gastrocnemius/calf muscle, 272 Gastronemius muscle scan and normal tissue appearance, 268 Glenohumeral (GH) joint, 220–222 Gout, 240 double-contour versus interface reflex, 242 Groin pain, 191 probe, 194 superficial anterior hip and groin musculature, 194 transducer selection, 191 types, 206 Guided vs. unguided/fluoroscopically-guided injections, accuracy of, 214–215 H Hand and fingers, 27, 28, 45 linear array probe, 28 Hepatorenal recess (Morison’s pouch), 277 Hernias, 208–211 High grade tear of gastrocnemius muscle at myotendinous junction, 268 Hip anterior, 171–176 blood vessels, 179–190 iliopsoas bursa, 178 lateral, 180–185 linear transducer, 169 posterior, 186–188

Index and sacroiliac joint, 229–230 Hip joint, 227 injection, 228 Hydrodissection, 219 of ulnar nerve, 220 I Image balance, 12 Impingement/labrum, pain generator, 190 Indirect inguinal hernia, 208–211 Individual certification for MSK/US, 4 Inflammatory bowel disease (IBD)-associated arthritis, 240 Inguinal hernias, 198 In-plane injection technique, 217 Internal snapping hip, 202–205 Intersection syndrome, 53 IT band syndrome, 167 K Knee, 150–164 anterior structures, 147 cross-sectional anatomy, 148 posterior deep structures, 166 Kozaci protocol for determination of fractures with POCUS, 259 L Lateral ankle, 132 Lateral collateral ligament (LCL), 149 Lateral elbow, 75 structures, 77 Lateral epicondyle of humerus, 223 Lateral epicondylosis, 92 Lateral hip, 178–179 Lateral knee, 149 Lateral shoulder, 101 Left 5thproximal metacarpal fracture, 260 with intra-articular extension of female Taekwondo athlete, 261 Ligaments, 22 injuries, 264, 266 Linear/curved linear transducer, 8, 166, 280 Linear, curvilinear and “hockey stick” probe, 16 Lung scan for pneumothorax, 274 M Medial ankle, 136 Medial elbow, 75, 77 Medial epicondylosis, 91–92 Medial knee, 148–149 Medial malleolus, gel standoff technique, 251 Medial/lateral epicondyle, 223 Medial patellofemoral ligament (MPFL), 148 Median nerve, 249 Medical clinics at recent Olympic and Paralympic games, 257 Meniscal tear, 166 Metacarpophalangeal (MCP) joint from dorsal, 243 and IP joint arthritis, 44, 167, 226–227, 238, 240, 242–244 midtarsal, 234 from volar, 243 M-Mode (motion mode), 11 Mobile, 7 Morton’s neuroma, 234–235

Index MSU tophi and CPPD crystals, 241 Muscle contusion, 267 Muscle scarring, 268 Muscle strain, 266 Muscle trauma, 266 Myositis ossificans, 268 N Nasal bone and cartilage ultrasound, 262 Nasal bone fracture, 261 Needle guidance procedures, 5–6 Needle Steering techniques, 219 Needle trauma, 215 Nerve block technique, 216, 230 Nerve hydrodissection, 219 Normal tissue architecture, 22 O Ocular ultrasound, 271 in acute ocular trauma, 271–272 Olecranon Bursitis, 92 On-site POCUS for sports-related musculoskeletal injuries, 258–260 Osgood-Schlatter’s Disease, 167 Out-of-plane injection technique, 218 P Partial-thickness rotator cuff tear, 96 Passive dorsal and plantar flexion of ankle, 133 Patellar dislocation, 167 Patellar tendinopathy, 166 Pericardial effusion, 277 Peripheral nerves, 23, 24, 247–253 Pes anserine bursitis, 167, 231 injection, 232 PIP joint from volar, 244 Piriformis syndrome, 190 Plantar aponeurosis, 233–234 Plantar fascia central cord injection, 234 Plantar fasciopathy, 233 Pneumothorax with POCUS, 273, 274 POC MSK/US scanning, 1 Point of Care Ultrasound (POCUS) detection of fractures, 257 machine set up and supplies, 258 preparation and set up of portable ultrasound, 257–258 for sports-related non-musculoskeletal injuries, 271–273 ultrasound scanning, 258 Portable lap top style ultrasound machine, 258 Portable machines, 7 types, 257–258 Posterior elbow, 75, 77 Posterior hip, 179 Posterior interosseous nerve (PIN) impingement, 75, 91 Posterior knee, 149–166 Posterior shoulder, 101, 115 anatomy, 101 Posterior tibialis tendon partial tear, 262, 267 Post-image processing ability, 9 Postoperative hip, 206–207 Power Doppler, 11–12 Practice accreditation, 5 for musculoskeletal ultrasound, 3

285 Prepatellar Bursa, 231 Probe axis to imaged structure, 18 Probe coupling agents, 18 Probe handling, 17 Probe manipulations, 18–19 Probe movements, 20 Probe orientation to patient, 18 Probe selection, 90 Protocol eFAST (Extended Focused Assessment with Sonography in Trauma), 277 Proximal interphalangeal joint, 244 Proximal tibiofibular joint, 149 Psoas bursa, 227–228 Psoriatic arthritis, 240 Pubic symphysis, 193 Pulley injection for trigger finger, 227 Pulsed wave/Duplex Doppler, 11 Q Quadriceps tendon rupture, 167 Quality assurance guidelines, 9 R Radial nerve, 250 Reactive arthritis, 240 Rectus abdominis, 193 Refraction artifact, 21, 22 Reverberation artifact, 21 Rheumatic problems, hand, wrist/elbow, 237, 239–245 Rib fractures, 260–262 Rib ultrasound, 260–261, 263 Rocking: tilting (heel-toe movement) of probe, 19 Rupture of right 4th flexor digitorum profundus (Jersey Finger), 262, 263, 268 S Sacroiliac (SI) Joint, 228–229 injection, 229 Scanning frequency, 8 of particular body part, 13 Service contracts, 9 Shoulder anisotropy, 98 clavicle, 95 color flow, 99 depth of visual field, 99 humerus, 95 imaging via ultrasound, 99 linear array probe, 95 orientation, 99 pathologic conditions, 95 patient positioning, 98 scapula, 95 Shoulder dislocations, 268, 270, 271 Skeletal muscle, 22 Small-footprint “hockey stick” probes, 8 Small tear of biceps muscle and hematoma formation, 268 Smartphone, 8 Snapping hip syndrome, 195–198, 202–205 Sono-palpation, 24 Spigelian hernias, 208–211 Split-screen comparison, 25

286 Sports-related groin pain, 199 Standoff pad, 18 Sterile technique, 219 Stress views, 25 Subacromial bursitis, 97 Subacromial-subdeltoid (SASD) bursa, 220, 221 Subacromial-subdeltoid bursitis, 97 Subcutaneous tissue, 23 Superficial anterior hip and groin musculature, 201 Superficial structures, 90 Superior and lateral shoulder, 112 Suprapatellar effusions, 167 Suprapatellar recess, 230–231 Suprascapular nerve block, 221–223 Supraspinatus and infraspinatus tendon injuries, 263 Synovial hyperemia, artifact versus real signal, 242–243 Synovitis, 238–239, 241 T Tablet, 8 Talocrural joint, 231–232 Tarsal tunnel syndrome, 233 Tendons, 22 injuries, 262 Tenosynovitis, 29, 239, 262 Thumb carpometacarpal (CMC) joint, 226 Tibial nerve, 251 Time-gain compensator sliders (TGCs), 9 set of controls, 12 Tissue scanning, 15–26 Transducers, 7 care and cleaning, 9–10 Traumatic vitreous hemorrhage, 271 Trigger Finger, 227 Trochanteric bursitis, 190, 229 injection, 230

Index U Ulnar collateral ligament injury, 92 of thumb/elbow, 13 Ulnar nerve, 249–250 Ultrasound equipment, 7–10 Ultrasound gel, 18 Ultrasound guidance (USG) injection, 219 in carpal tunnel injections, 224, 225 for percutaneous procedures, use of, 213 Ultrasound image acquisition, 17 Ultrasound imaging artifact, 19 Ultrasound imaging of normal tissue, 22 Ultrasound machine comparison, 10 Ultrasound novices, 9 Ultrasound-guided injections, 216–218 vs. landmark-guided injections accuracy of, 213, 215 efficacy studies, 216 safety and patient comfort considerations, 215–216 Ultrasound of bone fractures, 259 Ultrasound terminology, 16 Undifferentiated spondyloarthritis, 240 V Volar long-axis view of fingertip, 245 Volar plate injuries, 29 W Warranties and extended service contracts, 9 Wrist, 53–72 dorsal aspect, 51–52 median nerve, 52 probe selection and presets, 52 volar aspect, 51 Wrist first dorsal compartment injection, 226