Revision Total Hip and Knee Arthroplasty [1 ed.] 9780781760430, 2012018871, 9781451153873, 1451153872, 9781469878348, 1469878348

Citation preview

R E V I S I O N T O TA L

Hip and Knee Arthroplasty

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REVISION TOTAL

Hip and Knee Arthroplasty EDITORS

Daniel J. Berry, MD

Douglas A. Dennis, MD

Professor and Chairman Department of Orthopedic Surgery Mayo Clinic College of Medicine Mayo Medical School Rochester, Minnesota

Adjunct Professor Department of Biomedical Engineering University of Tennessee Knoxville, Tennessee Adjunct Professor of Bioengineering University of Denver Director Rocky Mountain Musculoskeletal Research Laboratory Denver, Colorado

Robert T. Trousdale, MD Professor of Orthopaedic Surgery Mayo Clinic College of Medicine Consultant in Orthopaedic Surgery Mayo Clinic Rochester, Minnesota

Wayne G. Paprosky, MD Professor Rush University Medical Center Chicago, Illinois

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Acquisition Editor: Brian Brown Product Manager: Dave Murphy Developmental Editor: Franny Murphy Marketing Manager: Lisa Lawrence Design Manager: Holly McLaughlin Manufacturing Manager: Benjamin Rivera Production Service: SPi Global Copyright © 2012 by LIPPINCOTT WILLIAMS & WILKINS, a WOLTERS KLUWER business Two Commerce Square 2001 Market Street Philadelphia, PA 19103 USA LWW.com All rights reserved. This book is protected by copyright. No part of this book may be reproduced in any form by any means, including photocopying, or utilized by any information storage and retrieval system without written permission from the copyright owner, except for brief quotations embodied in critical articles and reviews. Materials appearing in this book prepared by individuals as part of their official duties as U.S. government employees are not covered by the above-mentioned copyright. Printed in China Library of Congress Cataloging-in-Publication Data Revision total hip and knee arthroplasty / edited by Daniel J. Berry ... [et al.]. p. ; cm. Includes bibliographical references and index. Summary: This multi-contributed, comprehensive book covers revision surgery for total hip and knee arthroplasty. The focus of Revision Total Hip and Knee Arthroplasty will be on the techniques of revision surgery. Separated into a hip section and a knee section, each will include evaluation of the failed replacement, revision surgery, surgical technique, revision for specific diagnosis, complications, and postoperative management”—Provided by publisher. ISBN 978-0-7817-6043-0 I. Berry, Daniel J. [DNLM: 1. Arthroplasty, Replacement, Hip—methods. 2. Arthroplasty, Replacement, Knee—methods. 3. Hip Joint—surgery. 4. Knee Joint—surgery. 5. Postoperative Complications—prevention & control. 6. Reoperation—methods. WE 860] 617.5'810592—dc23 2012018871 Care has been taken to confirm the accuracy of the information presented and to describe generally accepted practices. However, the authors, editors, and publisher are not responsible for errors or omissions or for any consequences from application of the information in this book and make no warranty, expressed or implied, with respect to the currency, completeness, or accuracy of the contents of the publication. Application of the information in a particular situation remains the professional responsibility of the practitioner. The authors, editors, and publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accordance with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any change in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new or infrequently employed drug. Some drugs and medical devices presented in the publication have Food and Drug Administration (FDA) clearance for limited use in restricted research settings. It is the responsibility of the health care provider to ascertain the FDA status of each drug or device planned for use in their clinical practice. To purchase additional copies of this book, call our customer service department at (800) 638-3030 or fax orders to (301) 223-2320. International customers should call (301) 223-2300. Visit Lippincott Williams & Wilkins on the Internet: at LWW.com. Lippincott Williams & Wilkins customer service representatives are available from 8:30 am to 6 pm, EST. 10 9 8 7 6 5 4 3 2 1

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To our mentors, our colleagues, our students, our patients, and our families.

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C O N T EN TS

Contributors xi Preface xvii

SECTION 3

Planning, Decisions, and Approaches in Revision THA 75

SECTION 1

Perioperative Management of Revision Total Hip Arthroplasty and Total Knee Arthroplasty Patients 1

1

Anesthesia and Pain Management

3

Terese T. Horlocker

2

Venous Thromboembolism Prevention

7

Critical Decisions in Revision Total Hip Arthroplasty 77 Daniel J. Berry

8

Operative Approaches

89

Daniel J. Berry

17

SECTION 4

Yi-Meng Yen and Jay R. Lieberman

3

Medical Morbidity and Mortality Following Revision Total Hip and Knee Arthroplasty 33 Jeanne M. Huddleston and Kulsum D. Casey

Revision Techniques

9

Acetabular Component Removal

111 113

Douglas A. Dennis and Lee McFadden

10

SECTION 2

Acetabular Revision with Metal Shell Retention

125

William A. Jiranek

Evaluation of the Failed Total Hip Arthroplasty

4

Mechanisms of Total Hip Arthroplasty Failure

45 47

Evaluation of the Painful and Problematic Total Hip Arthroplasty 57 Paul F. Lachiewicz

6

Indications for Revision Total Hip Arthroplasty Tony Danesh-Clough and Steven J. MacDonald

Acetabular Bone Loss Classification

133

Scott M. Sporer, Wayne G. Paprosky, Karl Dermingian, and Brett Levine

Piya Pinsornsak and Thomas P. Schmalzried

5

11 12

Acetabular Reconstruction Options Based on Bone Loss

139

Daniel J. Berry

13

Cementless Acetabular Reconstruction in Revision Total Hip Arthroplasty 155 Craig J. Della Valle and Aaron G. Rosenberg

65

14

Uncemented Hemispherical Cups in Extreme Bone Loss

163

R. Michael Meneghini, Arlen D. Hanssen, and David G. Lewallen

vii

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15

CONTENTS

The Use of Cages in Revision Arthroplasty of the Acetabulum

179

Allan E. Gross and Stuart M. Goodman

16

Triflange Cup

193

28

Pelvic Discontinuity

321

Daniel J. Berry

29

David K. DeBoer and Michael J. Christie

17

Allograft Prosthetic Composite

Proximal Femoral Replacement with Megaprostheses

331

David J. Jacofsky

203

SECTION 5

Daniel J. Berry and Wayne G. Paprosky

18

Use of Structural Allografts in Acetabular Revision Surgery 215 Scott M. Sporer, Wayne G. Paprosky, and Michael O’Rourke

19

Femoral Component and Cement Removal

Femoral Bone Loss Classification

Femoral Reconstruction Options Based on Bone Loss

Cemented Femoral Component Revision

259

34

Proximally Porous-Coated Modular Stems

279

Calcar Replacement Stems

287

Extensively Porous-Coated Stems

293

385

Heterotopic Ossification

395

Complications and Postoperative Management

35

Fluted Tapered Uncemented Femoral Stems

Impaction Grafting of the Femur

Prevention and Management of Complications Following Total Hip Arthroplasty

407

409

Daniel J. Berry

303

Daniel J. Berry

27

Periprosthetic Osteolysis

SECTION 6

Scott M. Sporer, Wayne G. Paprosky, Karl Dermingian, and Brett Levine

26

Postoperative Periprosthetic Femur Fracture Around Total Hip Arthroplasty 361

Vincent D. Pellegrini, Jr.

Keith R. Berend and Adolph V. Lombardi Jr.

25

Revision for Hip Instability After Total Hip Arthroplasty 347

William Maloney

271

Thomas Parker Vail

24

339

Daniel J. Berry

33

Adam A. Sassoon and Daniel J. Berry

23

Surgical Management of the Infected Total Hip Arthroplasty

Matthew P. Abdel and Daniel J. Berry

32

Daniel J. Berry

22

31

243

Neil P. Sheth, and Wayne G. Paprosky

21

30

337

Brian J. Keyes, R. Michael Meneghini, and Arlen D. Hanssen

221

Andrew H. Glassman

20

Revision/Reoperation for Specific Diagnoses

36

Postoperative Care Following Revision Total Hip Arthroplasty 419 Daniel J. Berry

313

James A. Browne and Miguel E. Cabanela

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CONTENTS

46

SECTION 7

Evaluation of the Failed TKA

37

Mechanisms of Failure in Total Knee Arthroplasty

Evaluation of the Painful Total Knee Arthroplasty

47 425

The Aseptic, Failed Total Knee Arthroplasty: Indications for Revision

48 431

49 437

Preoperative Planning and Prosthetic Choices

Fixation Techniques in Revision Total Knee Arthroplasty

541

SECTION 10

447 449

Knee: Revision/Reoperation for Specific Diagnoses 545

50

Wound Complications

547

Henry D. Clarke, Susan Craig Scott, and W. Norman Scott

Michael E. Berend and Douglas A. Dennis

41

531

Robert T. Trousdale

SECTION 8

40

Managing the Patella in Revision Total Knee Arthroplasty R. Stephen J. Burnett and Robert L. Barrack

Tad M. Mabry and Mark W. Pagnano

Preoperative Strategy

Ligament Deficiency in Revision Total Knee Arthroplasty 517 Christopher M. Farrell and Giles R. Scuderi

Douglas A. Dennis

39

505

Gerard A. Engh and Deborah J. Ammeen

423

William L. Griffin

38

Major Bone Defect Management

ix

Operative Exposures For Revision Total Knee Arthroplasty 461 Robert T. Trousdale

51

Extensor Mechanism Complications

559

Douglas A. Dennis and Michael E. Berend

52

SECTION 9

The Infected Total Knee Arthroplasty: Prevention and Management 571 R. Michael Meneghini and Arlen D. Hanssen

Surgical Techniques

42

467

Removal of Implants in Revision Total Knee Arthroplasty 469

53

Douglas A. Dennis and Christopher B. Lynch

Daniel J. Berry

43

Balancing the Flexion and Extension Gaps in Revision Total Knee Arthroplasty 479 Bryan D. Springer and Thomas S. Thornhill

44

Classification of Bone Defects in Total Knee Revision 491 Joseph P. Turk and James P. McAuley

45

Minor Bone Defect Management in Revision Knee Arthroplasty J. Bohannon Mason and Richard D. Scott

Evaluation and Management of Periprosthetic Fractures after Total Knee Arthroplasty 589

54

Stiffness after Total Knee Replacement 601 Jess H. Lonner and Paul A. Lotke

55

Instability in Total Knee Arthroplasty

607

Kelly G Vince

SECTION 11

497

Salvage Procedures

56

Condylar Replacement Procedures

613 615

Mary I. O’Connor

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x

57

CONTENTS

Arthrodesis and Resection Arthroplasty of the Knee 621

59

Hari P. Bezwada, Jess H. Lonner, and Robert Booth Jr

Robert T. Trousdale

Index

SECTION 12

Complications and Postoperative Management

58

Postoperative Rehabilitation After Total Knee Replacement 651

655

633

Avoidance and Management of Intraoperative Complications in Revision Total Knee Arthroplasty 635 Raymond H. Kim, Douglas A. Dennis, and Robert T. Trousdale

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CO N T RI B UTOR S

Matthew P. Abdel, MD Department of Orthopedic Surgery Mayo Clinic Rochester, Minnesota Deborah J. Ammeen, BS Project Director Clinical Knee Research Anderson Orthopaedic Research Institute Alexandria, Virginia Robert L. Barrack, MD Charles and Joanne Knight Distinguished Professor of Orthopaedic Surgery Department of Orthopaedic Surgery Washington University School of Medicine Chief of Staff for Orthopaedic Surgery Director of Adult Reconstructive Surgery Department of Orthopaedic Surgery Barnes Jewish Hospital St. Louis, Missouri Keith R. Berend, MD Associate Joint Implant Surgeons, Inc New Albany, Ohio Vice-Chairman, Board of Directors New Albany Surgical Hospital New Albany, Ohio Clinical Assistant Professor Department of Orthopaedics The Ohio State University Columbus, Ohio Michael E. Berend, MD Fellowship Director Center for Hip and Knee Surgery Orthopaedic Section Chair St. Francis Hospital—Mooresville Mooresville, Indiana

Hari P. Bezwada, MD Penn Orthopaedics University of Pennsylvania School of Medicine Pennsylvania Hospital Philadelphia, Pennsylvania Robert Booth Jr, MD Chief Department of Orthopaedic Surgery Pennsylvania Hospital Philadelphia, Pennsylvania James A. Browne, MD Assistant Professor of Adult Reconstructive Surgery Department of Orthopaedic Surgery University of Virginia Charlottesville, Virginia R. Stephen J. Burnett, MD, FRCS(C) Assistant Professor Department of Orthopedic Surgery Washington University School of Medicine Barnes Jewish Hospital Saint Louis, Missouri Miguel E. Cabanela, MD Professor of Orthopedic Surgery Department of Orthopedic Surgery Mayo Clinic College of Medicine Consultant Department of Orthopedic Surgery Mayo Clinic Rochester, Minnesota Kulsum D. Casey, DO Instructor of Medicine Department of Medicine Mayo Clinic College of Medicine Senior Associate Consultant Mayo Clinic Hospital Rochester, Minnesota

Daniel J. Berry, MD Professor and Chairman Department of Orthopedic Surgery Mayo Clinic College of Medicine Mayo Medical School Rochester, Minnesota

xi

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xii

CONTRIBUTORS

Michael J. Christie, MD Co-founder Southern Joint Replacement Institute Medical Director St Thomas Joint Replacement Program Nashville, Tennessee Associate Clinical Professor Department of Orthopaedics Vanderbilt University Chairman Walk Strong Foundation Nashville, Tennessee Henry D. Clarke, MD Assistant Professor of Orthopedics Department of Orthopedics Mayo Clinic College of Medicine Senior Associate Consultant Department of Orthopedics Mayo Clinic Scottsdale, Arizona Tony Danesh-Clough, MB, ChB, FRACS Orthopaedic Surgeon Department of Orthopaedic Surgery North Shore Hospital Auckland, New Zealand David K. DeBoer, MD Director of Research Southern Joint Replacement Institute Assistant Clinical Professor Department of Orthopedics Vanderbilt University Medical Center Nashville, Tennessee Craig J. Della Valle, MD Department of Orthopaedic Surgery Rush University Medical Center Chicago Illinois Douglas A. Dennis, MD Adjunct Professor Department of Biomedical Engineering University of Tennessee Knoxville, Tennessee Adjunct Professor of Bioengineering University of Denver Director Rocky Mountain Musculoskeletal Research Laboratory Denver, Colorado Karl Dermingian, MD Arthroplasty Fellow Rush University Medical Center Chicago, Illinois

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Gerard A. Engh, MD Director, Knee Research Anderson Orthopaedic Research Institute Alexandria, Virginia Christopher M. Farrell, MD Fellowship in Adult Reconstruction and Sports Medicine of the Knee Lenox Hill Hospital New York, New York Andrew H. Glassman, MD, MS Assistant Professor Department of Orthopaedics The Ohio State University Staff Surgeon The Halley Orthopaedic Clinic Columbus, Ohio Stuart M. Goodman, MD, PhD, FRCSC, FACS Professor and Chief Division of Orthopaedic Surgery Stanford University Medical Center Stanford, California William L. Griffin, MD Chairman of the OrthoCarolina Research Institute Director of the OrthoCarolina Hip & Knee Center OrthoCarolina Charlotte, North Carolina Allan E. Gross, MD Head, Division of Orthopaedic Surgery Mount Sinai Hospital Professor of Surgery Faculty of Medicine University of Toronto Toronto, Ontario, Canada Arlen D. Hanssen, MD Professor of Orthopedic Surgery Department of Orthopedic Surgery Mayo College of Medicine Mayo Clinic & Mayo Foundation Rochester, Minnesota Terese T. Horlocker, MD Professor of Anesthesiology and Orthopedics Department of Anesthesiology Mayo Clinic College of Medicine Rochester, Minnesota

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CONTRIBUTORS

Jeanne M. Huddleston, MD, FACP Assistant Professor Department of Medicine Mayo Clinic College of Medicine Program Director, Hospital Medicine Fellowship Department of Medicine Mayo Clinic Rochester, Minnesota David J. Jacofsky, MD Chairman The CORE Institute Center for Orthopedic Research and Education Phoenix, Arizona William A. Jiranek, MD Associate Professor Department of Orthopedic Surgery Virginia Commonwealth University Chief, Adult Reconstruction Section Department of Orthopaedic Surgery MCV Hospitals Richmond, Virginia Brian J. Keyes, DO Department of Orthopaedic Surgery Indiana University School of Medicine Indianapolis, Indiana Raymond H. Kim, MD Orthopedic Surgeon Colorado Joint Replacement Denver, Colorado

Jay R. Lieberman, MD Director New England Musculoskeletal Institute Professor and Chairman Department of Orthopaedic Surgery University of Connecticut Health Center Farmington, Connecticut Adolph V. Lombardi Jr, MD, FACS Senior Associate Joint Implant Surgeons, Inc. New Albany, Ohio President of Medical Staff Services New Albany Surgical Hospital New Albany, Ohio Clinical Assistant Professor Department of Orthopaedics The Ohio State University Columbus, Ohio Clinical Assistant Professor Department of Biomedical Engineering The Ohio State University Columbus, Ohio Jess H. Lonner, MD Director of Knee Replacement Surgery Pennsylvania Hospital Booth Bartolozzi Balderston Orthopaedics Philadelphia, Pennsylvania Paul A. Lotke, MD Professor of Orthopaedic Surgery Hospital of the University of Pennsylvania Philadelphia, Pennsylvania

Paul F. Lachiewicz, MD Professor Department of Orthopaedics University of North Carolina at Chapel Hill Chapel Hill, North Carolina

Christopher B. Lynch, MD Orthopaedic Surgeon The Orthopaedic Group New Haven, Connecticut

Brett Levine, MD Arthroplasty Fellow Rush University Medical Center Chicago, Illinois

Tad M. Mabry, MD Assistant Professor of Orthopedics Mayo Clinic Rochester, Minnesota

David G. Lewallen, MD Professor Mayo Clinic College of Medicine Department of Orthopaedic Surgery Mayo Clinic Rochester, Minnesota

Steven J. MacDonald, MD Division of Orthopedic Surgery University of Western Ontario University Hospital London, Ontario, Canada

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xiii

William Maloney, MD Professor and Chairman Orthopaedic Surgery Stanford University Stanford, California

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xiv

CONTRIBUTORS

J. Bohannon Mason, MD Adjunct Professor William States Lee College of Engineering University of North Carolina at Charlotte Charlotte, North Carolina James P. McAuley, MD Associate Clinical Professor Department of Orthopaedic Surgery University of Maryland Consultant Anderson Orthopaedic Institute Alexandria, Virginia Lee McFadden, MD Madigan Army Medical Center Fort Lewis Tacoma, Washington R. Michael Meneghini, MD Staff Orthopedic Surgeon Department of Orthopaedic Surgery Joint Surgeons of Indiana St. Vincent Center for Joint Replacement Indianapolis, Indiana Mary I. O’Connor, MD Associate Professor and Chair Department of Orthopedic Surgery Mayo Clinic Jacksonville, Florida Michael O’Rourke, MD Assistant Professor The University of Iowa Iowa City, Iowa Mark W. Pagnano, MD Professor of Orthopaedic Surgery Mayo Clinic Rochester, Minnesota Wayne G. Paprosky, MD Professor Rush University Medical Center Chicago, Illinois Vincent D. Pellegrini Jr, MD James Lawrence Kernan Professor and Chair Department of Orthopaedics University of Maryland School of Medicine Baltimore, Maryland Piya Pinsornsak, MD Joint Replacement Institute Orthopaedic Hospital Los Angeles, California

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Aaron G. Rosenberg, MD Professor of Surgery Director of Adult Orthopedic Reconstruction Department of Orthopedic Surgery Rush University Medical College Chicago, Illinois Adam A. Sassoon, MD Department of Orthopedic Surgery Mayo Clinic Rochester, Minnesota Neil P. Sheth, MD Attending Orthopaedic Surgeon OrthoCarolina Hip and Knee Center Charlotte, North Carolina Thomas P. Schmalzried, MD Associate Medical Director Joint Replacement Institute Los Angeles, California Richard D. Scott, MD Professor of Orthopaedic Surgery Harvard Medical School Chief Department of Arthroplasty Service Brigham and Women’s New England Baptist Hospitals Boston, Massachusetts Susan Craig Scott, MD Attending Surgeon Department of Orthopedic Surgery Hand Surgery Service Hospital for Joint Diseases New York, New York W. Norman Scott, MD, FACS Clinical Professor of Orthopedic Surgery Department of Orthopedics Albert Einstein College of Medicine Attending Orthopedic Associate Department of Orthopedics Lenox Hill Hospital New York, New York Giles R. Scuderi, MD Director Insall Scott Kelly Institutes for Orthopedics and Sports Medicine Attending Orthopedic Surgeon Lenox Hill Hospital New York, New York

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CONTRIBUTORS

Scott M. Sporer, MD Assistant Professor Rush University Medical Center Chicago, Illinois Bryan D. Springer, MD OrthoCarolina Charlotte Hip and Knee Center Charlotte, North Carolina Thomas S. Thornhill, MD Professor and Chairman Department of Orthopaedic Surgery Brigham and Women’s Hospital and Harvard Medical School Boston, Massachusetts Robert T. Trousdale, MD Professor of Orthopaedic Surgery Mayo Clinic College of Medicine Consultant in Orthopaedic Surgery Mayo Clinic Rochester, Minnesota

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xv

Joseph P. Turk, MD Attending Orthopedic Surgeon Ventura Orthopedics and Sports Medicine Los Robles Hospital Department of Orthopedic Surgery Thousand Oaks, California Thomas Parker Vail, MD Associate Professor of Orthopaedic Surgery Director of Adult Reconstructive Surgery Duke University Medical Center Durham, North Carolina Kelly G. Vince, MD FRCS (C) Associate Professor Keck School of Medicine of the University of Southern California Los Angeles, California Yi-Meng Yen, MD, PhD Clinical Instructor of Orthopaedics Harvard Medical School Boston, Massachusetts

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P REFAC E

s the use of primary hip and knee arthroplasty soared in the last two decades, and as these mechanical devices inevitably failed in some patients, a new field—revision joint arthroplasty—was born. From the beginning it has been clear that revision surgery is fundamentally different from primary surgery in many ways. A failed implant must be removed, bone loss and soft tissue damage from implant failure or previous surgeries needs to be effectively managed, and the specific reasons for failure of the previous arthroplasty must be addressed. The broad spectrum of failure modes and tremendous variety of bone and soft tissue loss patterns requires surgeons to approach many complex problems with both creativity and ingenuity. To address these challenges, new classification methods to provide an intellectual framework for management needed to be created, new surgical techniques had to be developed, and new implants and materials needed to be manufactured. The past decade has seen revision hip and knee arthroplasty move from operations with often unpredictable results and limited durability to procedures that, while often still technically difficult, are far more reliable and long lasting. At the same time, improved implants and techniques have allowed surgeons to effectively treat even some of the most extreme problems. In short, revision hip and knee arthroplasty have “come of age” as effective, and usually successful procedures. Consider the remarkable progress and what has been learned about revision arthroplasty since the inception of joint replacement. Classification systems that help surgeons manage bone loss, instability, infection, soft tissue damage, and periprosthetic fractures in an organized and logical manner have been developed. Surgical exposures to address the unique needs of hip and knee revision challenges have evolved rapidly. Effective methods to remove cemented and uncemented implants, efficiently and with little loss of bone, have been pioneered in hip and knee arthroplasty. Gaining reliable fixation of a new arthroplasty, after failure of a previous implant, has been the focus of much effort in revision surgery, and new methods, implants, and materials have completely revolutionized

A

the likelihood of long-term success in this essential endeavor. Management of bone loss has evolved quickly with impacted cancellous allograft, bulk allografts, and solid and highly porus metal augments all playing important roles. Soft tissue deficiency, especially around the knee, now has a number of solutions. Management of complications including infection, instability, and periprosthetic fractures is now far more successful thanks to innovations and new implants. And finally, perioperative management of patients has improved, allowing these procedures to be done with less morbidity. This book is designed to provide the surgeon performing revision hip and knee surgery with a comprehensive reference source to this maturing field. The editors are all surgeons whose practice consists of a large amount of revision surgery and who have spent a lot of time thinking about how to move this field forward. We have deliberately written a number of the chapters ourselves, in hopes of providing some consistent philosophical underpinning to this complex subject. At the same time, we believe there are often many successful methods to approach a problem, and that a large number of “arrows in the quiver” helps the surgeon successfully manage the diverse problems encountered in revision operations. To this end we have asked some of the best, most thoughtful, and most talented surgeons and authors to contribute to this book, and their insights and perspectives are an essential aspect of the breadth and scope of the material provided to the reader. We hope readers of this text will find the book practical, educational, and most of all useful. Patients with complex revision problems can be among the most disabled and desperate in orthopaedics: we hope this book will help surgeons find and successfully apply effective methods to solving their challenging problems. Daniel J. Berry Douglas Dennis Wayne Paprosky Robert Trousdale

xvii

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SECTION

1 Perioperative Management of Revision Total Hip Arthroplasty and Total Knee Arthroplasty Patients

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CHAPTER

1

Terese T. Horlocker

Anesthesia and Pain Management

PREOPERATIVE ASSESSMENT MONITORING REQUIREMENTS CHOICE OF ANESTHETIC TECHNIQUE REVISION HIP ARTHROPLASTY REVISION KNEE REPLACEMENT POSTOPERATIVE ANALGESIA NEURAXIAL ANESTHESIA AND ANALGESIA IN THE ORTHOPAEDIC PATIENT RECEIVING ANTITHROMBOTIC THERAPY SUMMARY

Revision total hip and knee arthroplasty are complicated surgical procedures and represent a challenge to the surgeon and anesthesiologist. Patients requiring revision surgery often are elderly with significant medical conditions that complicate perioperative management. Specific concerns and considerations of the orthoapedic anesthesiologist include patient positioning, management of the difficult airway, blood loss and replacement, and optimization of postoperative pain management (sometimes in patients with chronic opioid dependence). Regional blockade may be performed to provide not only intraoperative anesthesia but also postoperative analgesia, allowing early mobilization and rehabilitation. However, since the potential for nerve injury due to patient, surgical, or anesthetic factors exists, these techniques must be appropriately applied.1 Finally, the patient undergoing total knee or hip revision arthroplasty is also at risk for deep venous thrombosis (DVT) and pulmonary embolism (PE). Potential interactions between anticoagulants and anesthetic drugs or regional anesthetic techniques must be thoroughly understood to reduce the risk of perioperative bleeding. Knowledge of the specific surgical techniques, including duration, extent, predicted blood loss, and associated complications, is invaluable to the anesthesia care provider working in a team to provide the best possible patient care. This chapter discusses the anesthetic techniques and patient management issues unique to patients undergoing revision hip or knee arthroplasty.

PREOPERATIVE ASSESSMENT During the preoperative assessment, the patient is evaluated for preexisting medical problems, allergies, previous anesthetic complications, potential airway difficulties, and considerations relating to intraoperative positioning. Many patients undergoing orthopaedic surgery have rheumatoid arthritis. Systemic manifestations of this disease include pulmonary, cardiac, and musculoskeletal involvement. Particularly significant to the anesthesiologist is involvement of the cervical spine, temporomandibular joint, and larynx. Rheumatoid involvement of the cervical spine may result in limited neck range of motion, which interferes with airway management. Atlantoaxial instability, with subluxation of the odontoid process, can lead to spinal cord injury during neck extension. Overall, patients undergoing major lower extremity orthopaedic procedures are considered at intermediate risk for cardiac complications perioperatively. However, it is often difficult to assess exercise tolerance or a recent progression of cardiac symptoms because of the limitations in mobility induced by the underlying orthopaedic condition. As a result, pharmacologic functional testing may be warranted based on clinical history. Perioperative cardiac morbidity may be decreased by the initiation of beta-blockade.2 The patient’s medications should be reviewed and the patient specifically instructed on which medications are to be continued until the time of surgery. Antihypertensive medications should NOT be discontinued, due to the risk of perioperative cardiac events. Likewise, patients who require chronic opioid medications should be allowed to maintain their dosing regimen. Steroid-dependent patients will require steroid replacement perioperatively. Finally, the patient should be queried regarding the use of any medications that affect hemostasis; many patients will have been instructed by their surgeon to begin thromboprophylaxis with aspirin or warfarin preoperatively. During the preoperative visit, the patient should undergo a focused physical examination. Patients should be assessed for limitation in mouth opening or neck extension, adequacy of thyromental distance (measured from the lower border of the mandible to the thyroid notch), and state of dentition. The heart and lungs should be auscultated. In addition, the site of proposed injection for regional anesthesia should be assessed

3

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4

SECTION 1 | PERIOPERATIVE MANAGEMENT

for evidence of infection and anatomic abnormalities or limitations. A brief neurologic examination, with documentation of any existing deficits, is crucial. The patient should also be evaluated for any potential positioning difficulties (during block performance or intraoperatively) related to arthritic involvement of other joints or body habitus. Hemoglobin and creatinine are assessed on all patients, as well as other laboratory testing and imaging performed as indicated by preoperative medical conditions. Because revision arthroplasty often is associated with substantial blood loss, the patient’s blood type should be determined and an antibody screen performed. Depending on the patient’s preoperative hemoglobin level, overall medical condition, and anticipated surgical procedure, several units of blood may be crossmatched preoperatively. For example, Nuttall et al.3 determined that a preoperative hemoglobin level of at least 15 g/dL markedly reduced the need for transfusion during primary and revision hip arthroplasty. Autologous blood donation may also be discussed and arranged, if appropriate. Ideally, the patient should also undergo a preoperative educational session that describes the surgical procedure, anesthetic and analgesic options, and the postoperative rehabilitative plan.

to provide superior postoperative analgesia, rapid postoperative rehabilitation, and reduced cost of medical care may result from thoughtfully implemented regional anesthetic and analgesic techniques.

REVISION HIP ARTHROPLASTY Positioning The lateral decubitus position commonly is used to facilitate surgical exposure for revision hip arthroplasty. In transferring the patient from the supine to lateral decubitus position, care must be taken to maintain the head and shoulders in a neutral position. The patient is supported while the position is secured with hip rests or other mechanical devices. The dependent arm is abducted and placed on a padded armrest; a rolled towel or wrapped intravenous fluid bag is placed in the axilla to avoid compression of the brachial plexus and vascular structures. The upper arm is placed on a padded overarm board. Continuous surveillance of the patient’s positioning and evaluation of pressure points is necessary to minimize preventable injury.

Anesthetic Technique Regional anesthetic techniques

MONITORING REQUIREMENTS Patients undergoing hip or knee revision require standard monitoring, including electrocardiogram, noninvasive blood pressure assessment, and pulse oximetry, regardless of anesthetic technique. In addition, many revision procedures are lengthy, with significant blood loss. Placement of an arterial cannula and urinary catheter facilitates fluid management and allows assessment of intraoperative measurement of hemoglobin and clotting parameters.

CHOICE OF ANESTHETIC TECHNIQUE Surgery to the hip and knee often is performed under regional anesthetic techniques. Neural structures may be blocked at the neuraxial (spinal, epidural), plexus (psoas compartment), or peripheral nerve (femoral, lateral femoral cutaneous, sciatic) levels. Regional anesthetics offer several advantages over general anesthetics among these patients, including improved postoperative analgesia, decreased incidence of nausea and vomiting, less respiratory and cardiac depression, improved perfusion via sympathetic block, reduced blood loss, and decreased risk of thromboembolism.4 The regional technique and local anesthetic solution used depend on a variety of factors, including duration of surgery, degree of sensory and motor block desired, and length of postoperative analgesia. Likewise, any patient who has an absolute contraindication to regional anesthesia (patient refusal, infection at the site of needle placement, systemic anticoagulation) is a candidate for general anesthesia. Thus, although revision hip and knee arthroplasty may be performed under both general and regional anesthesia, the ability

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are well suited to uncomplicated revision hip procedures of limited (3 to 4 hours) duration. However, a general anesthetic may be more appropriate for longer and more extensive procedures. Both hypobaric and isobaric spinal anesthetic solutions are effective. Adequate intravenous hydration before placing the spinal block protects against a precipitous drop in blood pressure that can occur secondary to sympathetic blockade and peripheral vasodilation. Epidural blockade also provides excellent surgical anesthesia. Placement of a neuraxial catheter allows prolonged anesthesia as well as postoperative analgesia. Recently, both single-dose and continuous lumbar plexus techniques have been performed to provide postoperative analgesia in patients undergoing major hip surgery. Psoas compartment block was associated with decreased postoperative pain and facilitated hospital discharge.5 The lumbar plexus block also contributes to the intraoperative anesthetic, allowing decreased dosing of volatile agents, opioids and/or spinal anesthetic solutions.

Blood Loss Most revision hip arthroplasties are associated with substantial blood loss, due to the nature and duration of the procedures. Preoperatively, it is important to make sure that sufficient blood products will be available. Intraoperative monitoring of blood loss and careful attention to volume status of the patient throughout the procedure are essential. Blood salvage methods may be useful in many larger revision procedures. Multiple studies demonstrate significantly reduced intraoperative blood loss during total hip arthroplasty (THA) completed under central neuraxial blockade compared with general anesthesia.6 The reasons for this reduction are unproved, but it may be influenced by the decrease in mean arterial pressure, blood flow redistribution to larger-caliber vessels, and locally

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CHAPTER 1 | ANESTHESIA AND PAIN MANAGEMENT

reduced venous pressure. Decreased postoperative blood loss can be demonstrated when the epidural local anesthetic is continued for analgesia. Deliberate hypotension also can be used with general anesthesia as a means of reducing surgical blood loss and has been recommended when the benefits can be expected to outweigh the risks.7 Diltiazem, nitroprusside, beta-blockade, and nitroglycerin have also been used to induce hypotension. Likewise, a complete sympathectomy achieved by a high neuraxial block, including blockade of the cardioaccelerator fibers (T1-4), has also been performed to provide a “bloodless” surgical field.8 Despite noteworthy results, the precise manipulation of blood pressure and vigilance required to balance adequate cerebral and cardiac perfusion pressure with surgical operating conditions has limited the application of this technique.

Intraoperative Hypotension and Cardiovascular Instability Hypotension that may uncommonly progress to cardiac arrest has been reported immediately after insertion of cemented (but not noncemented) femoral prostheses in patients under both neuraxial and general anesthesia.9 These events are uncommon in patients undergoing revision procedures due to the limited amount of marrow and fat within the femoral canal. Initially, it was believed that this hypotension directly related to vasodilatory and/or cardiac depressive effects of the methylmethacrylate cement. However, echogenic material has been noted with ultrasound imaging performed during femoral reaming, with insertion of cemented femoral component, and with relocation of the hip joint.10 This suggests that the etiology of the hypotension and cardiovascular instability are embolic (air, fat, marrow, thrombus) in origin, and not a toxic effect of the methylmethacrylate. Surgical techniques to reduce the risk of hypotension include venting the femoral shaft and cautious femoral reaming to decrease bone marrow displacement into the systemic circulation. Adequate hydration and maximizing inspired oxygen concentration minimize the hypotension and hypoxemia that can accompany cementing of the prosthesis. Since air can be entrained during this procedure, nitrous oxide should be discontinued several minutes prior to cement insertion. Moderate hypotension, or a decrease in mean arterial pressure (30% from baseline), may be treated with ephedrine 5 to 10 mg intravenously. However, intravenous epinephrine 10 to 20 mg is recommended in cases of severe acute hypotension. Prolonged resuscitation involving chest compressions, DC countershock, and high-dose epinephrine may be needed to reverse cardiovascular collapse.9

REVISION KNEE REPLACEMENT Patients undergoing revision knee arthroplasty experience significant postoperative pain. Thus, the anesthesiologist must devise a plan for not only intraoperative anesthesia but also postoperative analgesia.

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5

Positioning The supine position optimizes surgical exposure. Care must be taken to cushion the extremities and bony prominences.

Anesthetic Technique Regional anesthetic techniques that can be used for revision knee arthroplasty include neuraxial as well as peripheral leg blocks. Spinal anesthesia can be accomplished with hyperbaric or isobaric solutions, although the latter are favored by most orthopaedic anesthesiologists. Injection of hyperbaric solutions often results in a higher level of sensory and motor blockade than needed for the surgical procedure, with subsequent earlier offset of anesthesia. Epidural blockade offers the advantage of a continuous catheter technique that can be continued into the postoperative period. Surgical anesthesia for operative procedures on the knee in which a tourniquet will be used requires blockade of all four nerves (femoral, lateral femoral cutaneous, obturator, and sciatic nerves) innervating the leg. Although it is possible to perform major knee surgery under peripheral nerve blocks, more often a single-injection femoral three-in-one or lumbar plexus (psoas compartment) block is combined with a spinal or general anesthetic. This is less difficult technically and provides postoperative analgesia for 12 to 24 hours. Continuous lumbar plexus and sciatic techniques allow for prolonged postoperative analgesia and facilitate mobilization.5

Blood Loss and Pneumatic Tourniquet Inflation The use of intraoperative tourniquets makes intraoperative blood loss minimal. However, postoperative drainage may be in the range of 500 to 1,000 mL per knee (resulting in a decrease in hemoglobin level of 1 to 2 g/dL). Thus, postoperative monitoring of blood loss and hemodynamic parameters is necessary for patients considered high risk for either excessive bleeding or cardiovascular complications. Tourniquets are often used to minimize blood loss and provide a bloodless operating field. The cuff should be applied over limited padding or none at all. Appropriate selection of tourniquet cuff size and inflation pressure is paramount in reducing the risk of neuromuscular injury related to tourniquet ischemia. The cuff should be large enough to comfortably circle the limb to ensure circumferentially uniform pressure. The point of overlap should be placed 180 degrees from the neurovascular bundle because there is some area of decreased compression at the overlap point. The width of the inflated cuff should be more than half the limb diameter. Damage to underlying vessels, nerves, and muscles has been reported following tourniquet inflation.11 Injury is a function of both inflation pressure and duration of inflation.12,13 Direct pressure from the cuff is more damaging than the ischemia distally.12,14 Arterial spasm, venous thrombosis, and nerve injury are all demonstrable after several hours. Clinical examination, electromyography, and effluent blood analysis all show completely reversible changes for inflations of 1 to 2 hours, which is the basis for the recommendation of this period as the safe duration for tourniquet use; longer inflation

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times are associated with prolonged or irreversible changes in neurologic and/or muscular function.15 Opinions differ as to the pressure required in tourniquets to prevent bleeding. In general, a cuff pressure 100 mm Hg above a patient’s measured systolic pressure is considered appropriate. Likewise, the duration of safe tourniquet inflation is unknown. Recommendations range from 30 minutes to 4 hours. Five minutes of intermittent perfusion between 1- and 2-hour inflations, followed by repeated exsanguination through elevation and compression, may allow more extended inflation.1,16 Prolonged tourniquet inflation is associated with postoperative peroneal and/or tibial neuropathy.1,17 Transient systemic metabolic acidosis and increased arterial carbon dioxide levels have been demonstrated after tourniquet deflation, and do not cause deleterious effects in healthy patients. Prolonged inflation or the simultaneous release of two tourniquets may produce clinically significant acidosis, particularly in patients with an underlying acidosis due to other causes. Tourniquet release has also been associated with cerebral embolic phenomena.18 When a pneumatic tourniquet is used with regional anesthetic techniques, some patients complain of dull, aching pain or become restless, even though seemingly adequate analgesia exists for the operation itself. Patient discomfort usually appears approximately 45 minutes after the tourniquet is inflated and becomes more intense with time. No satisfactory explanation for its genesis has been found. The definitive treatment for tourniquet pain is release of the tourniquet. Relief of pain is prompt and complete. During surgery, however, opioids and hypnotics are usually effective.

POSTOPERATIVE ANALGESIA Failure to provide adequate postoperative analgesia impedes patient mobilization, physical therapy, and rehabilitation and potentially delays hospital dismissal. Traditionally, postoperative analgesia following total joint replacement was provided by either intravenous patient-controlled analgesia (PCA) or epidural analgesia. However, each technique has distinct advantages and disadvantages. For example, opioids do not consistently provide adequate pain relief and often cause sedation, constipation, nausea/vomiting and pruritus. Epidural

TABLE 1.1

infusions containing local anesthetics (with or without an opioid) provide superior analgesia but are associated with hypotension, urinary retention, motor block limiting ambulation, and spinal hematoma in association with anticoagulation. Recently, single-dose and continuous peripheral nerve techniques that block the lumbar plexus (fascia iliaca, femoral, psoas compartment blocks) with or without sciatic nerve blockade have been utilized in this patient population.19–22 Several studies have reported that unilateral peripheral block provided a quality of analgesia and surgical outcomes similar to that of continuous epidural analgesia, but with fewer side effects.19,20 This suggests that continuous peripheral techniques may be the optimal analgesic method following total joint arthroplasty.

Multimodal Analgesia Multimodal analgesia is a multidisciplinary approach to pain management, with the aim of maximizing the positive aspects of the treatment while limiting the associated side effects. Since many of the negative side effects of analgesic therapy are opioid related (and dose dependent), limiting perioperative opioid use is a major principle of multimodal analgesia. The use of peripheral or neuraxial regional anesthetic techniques and a combination of opioid and nonopioid analgesic agents for breakthrough pain results in superior pain control and attenuation of the stress response and decreases opioid requirements. Systemic Analgesics Opioid Analgesics. Adequate analgesia achieved with systemic opioids is frequently associated with side effects, including sedation, nausea, and pruritus. However, despite these well-defined side effects, opioid analgesics remain an integral component of postoperative pain relief. Systemic opioids may be administered by intravenous, intramuscular, and oral routes. Current analgesic regimens typically employ intravenous PCA for 24 to 48 hours postoperatively, with subsequent conversion to oral agents. The PCA device may be programmed for several variables including bolus dose, lockout interval, and background infusion (Table 1.1). The optimal bolus dose is determined by the relative potency of the opioid; insufficient dosing results in inadequate analgesia whereas excessive dosing increases the potential for side effects, including respiratory

Intravenous Opioids for PCA

Agent

Bolus

Lockout Interval

4-h Maximum Dose

Infusion Ratea

Fentanyl (10 mg/mL) Hydromorphone (Dilaudid ) (0.2 mg/mL) Meperidine (10 mg/mL)b Morphine sulfate (1 mg/mL)

10–20 mg 0.1–0.2 mg 5–25 mg 0.5–2.5 mg

5–10 min 5–10 min 5–10 min 5–10 min

300 mg 3 mg 200 mg 30 mg

20–100 mg/h 0.1–0.2 mg/h 5–15 mg/h 1–10 mg/h

aA

background infusion rate is not recommended for opioid-naïve patients. limit in healthy patients should be 800 mg in first 24 h and then 600 mg every 24 h thereafter.

bMeperidine

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CHAPTER 1 | ANESTHESIA AND PAIN MANAGEMENT

depression. Likewise, the lockout interval is based upon the onset of analgesic effects; too short a lockout interval allows the patient to self-administer additional medication prior to achieving the full analgesic effect (and may result in accumulation/overdose of the opioid). A prolonged lockout interval will not allow adequate analgesia. The optimal bolus dose and lockout interval are not known, but ranges have been determined. Varying the settings within these ranges appears to have little effect on analgesia or side effects. Although most PCA devices allow the addition of a background infusion, routine use in adult opioid-naïve patients is not recommended. There may be a role for a background opioid infusion in opioid-tolerant patients, however. Due to the variation in patient pain tolerance, PCA dosing regimens may need to be adjusted in order to maximize the benefits and minimize the incidence of side effects. The adverse effects of opioid administration can cause serious complications in patients undergoing major orthopaedic procedures. In a systematic review, Wheeler et al.23 reported gastrointestinal effects (nausea, vomiting, ileus) in 37%, cognitive effects (somnolence and dizziness) in 34%, pruritus in 15%, urinary retention in 16%, and respiratory depression in 2% of patients receiving PCA opioid analgesia. Oral opioids (Table 1.2) are available in immediaterelease and controlled-release formulations. Although immediate-release oral opioids are effective in relieving moderate to severe pain, they must be administered as often as every 4 hours. When these medications are prescribed “as needed” (prn), there may be a delay in the administration and a subsequent increase in pain. Furthermore, interruption of the dosing schedule, particularly during the night, may lead to an increase in the patient’s pain. The United States Acute Pain Management Guideline Panel currently recommends a fixed dosing schedule for all patients requiring opioid medications for more than 48 hours postoperatively (AHCPR Pub No 92-0032). The adverse effects of oral opioid administration are considerably less compared to those of intravenous administration, and are mainly gastrointestinal in nature.23 A controlled-release formulation of oxycodone (OxyContin) is also available and has been shown to provide therapeutic opioid concentrations and sustained pain relief over an extended time period. Combined with prn oxycodone for breakthrough pain, scheduled administration of controlled-release oxycodone maximizes the analgesia and decreases the associated side effects.24 Tramadol (Ultram) is a centrally acting analgesic that is structurally related to morphine and codeine (but is not truly an opioid). Its analgesic effect is through binding to the opioid receptors as well as blocking the reuptake of both norepinephrine and serotonin. Tramadol has gained popularity due to the low incidence of adverse effects, specifically respiratory depression, constipation, and abuse potential. Thus, tramadol may be used as an alternative to opioids in a multimodal approach to postoperative pain, specifically in patients who are intolerant to opioid analgesics.

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7

Nonopioid Analgesics (Acetaminophen and Nonsteroidal Anti-inflammatory Drugs). The addition of nonopioid analgesics reduces opioid use, improves analgesia, and decreases opioid-related side effects. The multimodal effect is maximized through selection of analgesics that have complementary sites of action. For example, acetaminophen acts predominantly centrally, while other nonsteroidal anti-inflammatory drugs (NSAIDs) exert their effects peripherally. The mechanism of analgesic action of acetaminophen has not been fully determined. Acetaminophen may act predominantly by inhibiting prostaglandin synthesis in the central nervous system. Acetaminophen has very few adverse side effects and is an important addition to the multimodal postoperative pain regimen, although the total daily dose must be limited to 65 y); 120 mg (50%) amount of viable host bone and providing the necessary mechanical stability to allow successful osseointegration of the acetabular component. To date, this has been most reliably achieved with cementless, porous-coated implants,1–3 which have achieved 96% to 98% 10-year survivorship with aseptic loosening as the endpoint. However, a retrospective review of all uncemented acetabular components, including 2,443 revisions, performed at the Mayo Clinic over a 15-year period documented acetabular failure that increased at a steady and progressive rate after a decade of in vivo use (Fig. 14-1).4 In addition, the long-term success of the implant is dependent on the extent of bone loss and subsequent remaining host bone. The same institution reviewed 60 revision acetabular reconstructions with a first-generation cementless hemispherical socket at a minimum of 5-year follow-up.

A 12% failure rate was observed in those hips requiring 50% allograft coverage at the time of socket revision.4 Severe bone loss represents a challenging problem in the revision acetabular reconstruction. Bulk allograft and antiprotrusio cages have been the predominant reconstruction methods for severe acetabular bone loss; however, the results of these two reconstruction methods have been largely disappointing. The results of antiprotrusio cages in the literature document mechanical failure rates of up to 15% at midterm follow-up.5–9 Recent reports document success rates of only 64% to 76% with antiprotrusio cages used for large acetabular defects,8,10 with a high rate of complications, including sciatic nerve neurapraxias, loss of implant fixation, and failure of the cage by flange fracture.10 Acetabular reconstruction with structural allograft also is fraught with inconsistent and suboptimal results, with mechanical failure rates from 6% to 44%11–16 and up to 70% component loosening and migration in the most severe acetabular defects.14 The decline in survivorship seen in cementless hemispherical components in revision acetabular reconstruction after the 10-year mark, and the inconsistent and suboptimal success of current techniques for reconstruction of large acetabular defects, serve as the impetus for the development of a new acetabular reconstruction method. Recently developed acetabular implants composed of a novel porous tantalum biomaterial have been used in conjunction with modular augments of identical material to create a single revision acetabular system with optimal biological and mechanical properties. The modularity of this system allows successful treatment of many severe bone defects encountered in revision acetabular surgery.

POROUS TANTALUM A new highly porous tantalum biomaterial has recently been developed for application in hip and knee reconstruction surgery. Tantalum has been shown to be biocompatible via the response of osteoblasts in cell culture.17 The highly porous version of this material is produced by the deposition of commercially pure tantalum on a carbon skeleton of

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FIGURE 14-1. Survivorship curve of 2,443 revision uncemented acetabular components preformed at Mayo Clinic from 1984 through 1998. A progressive and nonlinear increase in component failure is seen, most pronounced after the first decade in vivo.

interconnecting pores (Fig. 14-2). This metal construct is extremely porous (75% to 80% porous by volume), compared to the 40% to 50% and 30% to 35% porosity of fiber-metal mesh and sintered-bead coatings, respectively.18,19 The higher fractional volume available for ingrowth with porous tantalum provides a more rapid development of interfacial shear

FIGURE 14-2. Scanning electron micrograph of porous tantalum biomaterial, illustrating the three-dimensional, open-pored structure.

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strength. Histological analysis has demonstrated a 40% to 50% filling of pores with new bone at 4 weeks with a minimum interface fixation strength of 18.5 MPa, substantially higher than observed with other porous materials with less volumetric porosity.19 In addition to rapid bone ingrowth and increased interface strength, porous tantalum provides the important biomechanical properties of increased material elasticity and a surface coefficient of friction greater than other implant surfaces. The coefficient of friction for porous tantalum on cancellous bone (0.88 to 0.98)20 is significantly greater than that previously reported for traditional porous-coated and sintered-bead materials (0.50 to 0.66)21. The increased coefficient of friction with porous tantalum likely provides greater initial implant stability, which is critical to obtaining longterm biological fixation. Furthermore, the modulus of elasticity of porous tantalum is in between cortical and cancellous bone, and is significantly less than titanium and chromium cobalt materials.22 This optimal elasticity of porous tantalum likely creates a more physiologic transfer of stresses to the periacetabular bone and theoretically decreases detrimental stressshielding. Furthermore, the deformation of porous tantalum against hard cortical bone is attributable to its relative elasticity, a property that likely facilitates initial frictional stability and geometrical fit, while reducing the propensity for fracture upon complete implant seating.

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CHAPTER 14 | UNCEMENTED HEMISPHERICAL CUPS IN EXTREME BONE LOSS

In summary, the initial fixation provided by the porous tantalum coefficient-of-friction and decreased rigidity is supplemented by the rapid bone ingrowth and increased interface fixation strength to facilitate osseointegration. These material and biological properties of porous tantalum are likely beneficial in revision acetabular reconstruction, especially in the face of large acetabular defects or suboptimal bone quality.

REVISION ACETABULUM SYSTEM The porous tantalum acetabular reconstruction system has evolved into a family of implants designed to address the vast majority of clinical situations and acetabular defects encountered in the revision setting. The revision porous tantalum acetabular shell is a hemispherical component that is composed almost entirely of porous tantalum (Fig. 14-3A,B). The shell is not uniformly hemispherical, however, and has a slightly elliptical shape with a larger diameter at the shell’s periphery to obtain adequate interference fit, which is further enhanced by the increased elasticity of the novel material as discussed previously. The revision shell has a multitude of screw holes from the manufacturer, and a polyethylene liner is cemented into the implant. In addition, a high-speed carbide burr can be used to easily bore through the porous tantalum material. This provides the opportunity to place acetabular screw holes in the revision shell in the direction of optimal bone stock, providing maximal initial implant stability and fixation. Cementation of a polyethylene liner into a metal shell has been shown to be

165

equivalent to standard locking mechanisms in biomechanical testing,23 and when used with multiple appropriately placed acetabular bone screws, creates three-dimensional stability. This additional stability is obtained as the cement hardens around the acetabular screw heads and creates a fixed-angle or locking screw effect, analogous to the newly developed locking plates in orthopedic trauma surgery. Furthermore, early clinical follow-up of cemented liners into well-fixed acetabular components revealed no dissociation of the liner from the cement.24 In addition to the porous tantalum acetabular component designed for revisions, a modular trabecular metal shell has recently emerged with a locking mechanism for the polyethylene. This implant offers surgeons the advantages associated with modularity of the polyethylene liner; however, the inner titanium shell that lines the concave surface of the shell is rigid and imparts additional stiffness to the construct, rendering the porous metal material as a biologically friendly bone ingrowth surface without the benefits of elasticity for improved cup fixation. Furthermore, the surgeon is relegated to placing screws in the screw holes predetermined by the manufacturer, which may not be in the ideal position when attempting to gain fixation into deficient periacetabular bone. A novel system of modular porous tantalum augments has been developed to address and manage the multitude of large osseous defects that are frequently encountered in revision acetabular reconstruction. Multiple shapes and sizes of these augments (Fig. 14-3C,D) accommodate the various acetabular bone defects encountered and compliment the various

FIGURE 14-3. Porous-coated titanium (left) and porous tantalum (right) hemispherical acetabular components used in cementless revision acetabular reconstruction as viewed from the (A) concave and (B) outer convex surface. C,D: Modular porous tantalum augments of various sizes with fenestrations for supplemental bone graft.

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sizes of hemispherical acetabular components. The augments were developed and designed to obtain simultaneous biologic fixation and mechanical support to gain osseointegration of the uncemented hemispherical acetabular component to host bone. In addition, the augments are fenestrated to allow supplementation with morselized autograft or allograft. By obtaining mechanical and biological fixation, this porous tantalum augment system may allow the avoidance of structural allograft use, obviate the need for custom fabrication of implants, and provide a comprehensive system that facilitates the use of cementless hemispherical acetabular components by using the porous tantalum augments to address the wide variety of osseous defects encountered during these difficult reconstructions. If available host bone is inadequate to obtain mechanical stability with the use of the porous tantalum augments and a hemispherical trabecular metal shell, an integrated porous tantalum cup-cage construct can be utilized. This construct employs the addition of an “antiprotrusio cage” inset and cemented to a porous tantalum revision shell that does not have sufficient mechanical stability by itself to obtain bone ingrowth. This construct allows the uncemented hemispherical cup to be placed in optimal orientation against the remaining, yet mechanically insufficient host bone. The goal is to obtain long-term bone ingrowth facilitated by the mechanical support imparted by the cage cemented into the trabecular metal revision shell. Furthermore, this cage-cup construct allows optimal socket positioning as the separate polyethylene liner is cemented into place once the hemispherical shell, morselized bone graft, and cage are secured with acetabular screws and cement. This cup-cage construct provides a treatment solution to the most severe and challenging acetabular defects that typically render a hemispherical acetabular component unstable. In addition, the cup-cage construct has application in the setting of impaired bone quality secondary to severe osteoporosis or prior irradiation.

INDICATIONS AND BENEFITS The indications for acetabular revision include aseptic mechanical loosening, hip instability due to component malposition, and periprosthetic osteolysis associated with wear debris. An additional indication for revision total hip arthroplasty, albeit in a staged manner, is for periprosthetic infection necessitating removal and reimplantation of implants. Traditional porouscoated uncemented hemispherical titanium cups may be used for the vast majority of acetabular revisions with a high success rate, with 10-year survivorship rates of 96% to 98% with respect to aseptic loosening.1–3 However, as previously mentioned, disappointing results into the second decade of use in the revision setting with traditional porous-coated hemispherical implants4 (Fig. 14-1) has prompted the development of alternative implant materials, namely porous tantalum. Relative contraindications to acetabular revision with a traditional porous-coated titanium hemispherical shell include acetabular osteonecrosis due to radiation exposure, pelvic

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discontinuity, and severe global acetabular bone loss precluding adequate apposition of the hemispherical implant to viable host bone. However, it should be emphasized that these contraindications are relative, and the biological and mechanical characteristics of porous tantalum demonstrate some theoretical advantages in these challenging clinical settings and have been used with initial short-term success. Inherent in these indications and contraindications are the requisites for success with a cementless hemispherical acetabular implant in the revision setting. These requirements include an adequate amount of viable host bone contact to provide sufficient mechanical stability and the appropriate biological conditions to allow bone ingrowth and long-term clinical success. Although currently unsubstantiated by clinical or biomechanical studies, it is commonly accepted that at least 50% implant contact with host bone improved the likelihood of subsequent implant osseointegration. It is probable that the ability to achieve adequate mechanical fixation is additionally related to the specific location of viable host bone, the quality of host bone, and the biologic activity of the remaining bone in contact with the prosthesis. Early results suggest that the properties of porous tantalum may provide sufficient mechanical stability of the hemispherical implant in the setting of more severe bone deficiencies. For example, the increased coefficient of friction and increased elasticity of porous tantalum material may allow achievement of mechanical stability with a hemispherical implant in the setting of 50% host bone contact) 2B (moderate superolateral migration, >50% host bone contact) 2C (isolated medial migration, medial to Kohler line, intact peripheral rim) 3A (severe superolateral migration, 4 cm of isthmus remaining for diaphyseal fixation.

Tapered Stems Taper designed stems have gained enthusiasm in the last decade for their use in femoral revision THA. Tapered stems can be nonmodular or modular. With this taper design, concerns exist with stem subsidence and a heightened risk for stem fracture at the morse taper junction. Nonmodular stems capitalize on the absence of a second morse taper junction while modular stems allow for more options to restore hip biomechanics.

Modular Tapered Stems Modular tapered revision femoral components have been successfully used in the reconstruction of femurs with moderate-to-severe proximal bone loss.57–62 Park et al.60 followed 62 femoral revisions using a fluted modular tapered

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component (Lima-Uto, Udine, Italy) for a mean of 4.2 years (range, 2 to 7.8 years). Thirty-seven of sixty-two (60%) were classified as Paprosky type IIIA, and nineteen (31%) were type IIIB. None of the patients in this cohort required revision due to mechanical failure. In similarly designed studies, Garbuz et al.57 and Richards et al.61 compared the results of tapered, fluted, modular titanium femoral components (ZMR Hip System; Zimmer Inc., Warsaw, IN) to cylindrical, nonmodular cobalt chrome components (Solution System; Depuy Orthopaedics Inc., Warsaw, IN) in revision arthroplasty. Both studies reported superior results with the modular tapered components. Richards et al. found that although the modular tapered cohort had worse preoperative bone defects (65% Paprosky type IIIB and IV femurs vs. 32% in the nonmodular group),

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However, the lack of modularity makes proper component position and hip biomechanic restoration more difficult. Grunig et al.69 evaluated 38 revisions using the Wagner SL revision stem (Zimmer Inc., Warsaw, IN). With a mean follow-up of 47 months, 3 (8%) of 38 hips required revision for stem subsidence, and an additional 16 stems had subsided 20 mm and 22 of 43 (51%) had subsidence 150 mm can inhibit bone ingrowth into a cobalt-chromium substrate.11 Clinical results demonstrate that a 4- to 5-cm isth-

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mic segment is all that is required to obtain adequate initial fixation.12 The radiographic characteristics of an extensively coated stem are predictive of implant longevity. Engh et al. observed the changes that occur between 1 and 3 years postoperatively and have described three basic radiographic patterns.13 Extensively coated stems are classified as bone ingrown, stable fibrous fixation, or unstable fixation. The bone ingrowth pattern is characterized by the absence of migration of the implant, absence of radiolucent line around the porous portion of the stem, absence of endosteal hypertrophy at the distal limit of the porous coating, and no pedestal formation. Proximal bone resorption “stress shielding” is seen with extensively coated components since most ingrowth occurs distally on the stem, and as a result, the proximal femoral bone is not loaded. The second radiographic pattern of fixation is fibrous ingrowth. The component demonstrates no subsidence; yet a parallel reactive line adjacent can be seen adjacent to the porous coating. The characteristic feature of this line is that it parallels the contours of the implant, is separated from it by a narrow width (usually 1.0 to 1.5 mm), is not divergent, and does not progress with time. A small distal pedestal and mild proximal bone resorption may be present. The final radiographic pattern of an unstable implant is characterized by progressive implant migration, rotary instability, and tilting of the component into varus. Progressive, divergent, sclerotic lines are seen, and the proximal bone demonstrates hypertrophy. An endosteal pedestal is frequently present at the tip of the stem. With these radiographic characteristics, the implant is grossly unstable and clinically symptomatic.

INDICATIONS The most frequent indications for femoral revision include aseptic loosening, recurrent instability from a malpositioned component, component fracture, delayed infection, and the need for improved acetabular exposure. Relative indications for femoral component removal include progressive distal femoral osteolysis or during acetabular revision when a femoral component with a poor track record had previously been placed. The choice of implant used during the femoral reconstruction will be based largely upon the amount of femoral bone loss encountered at the time of revision surgery. Depending upon the clinical scenario, an extended trochanteric osteotomy may be required to facilitate component removal, remove distal cement, or avoid eccentric remaining in a varus remodeled femur. The senior author has previously described a femoral classification system that can assist the surgeon with preoperative planning for femoral revisions and can predict the extent of bone loss. This classification places the remaining femoral bone stock into one of four defect types. Type I defects have minimal damage to the proximal metaphysis and can be treated like a primary hip. Type II defects demonstrate mild

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CHAPTER 25 | EXTENSIVELY POROUS-COATED STEMS

295

FIGURE 25-1. Seventy-six-year old patient with aseptic loosening of her femoral implant. A: Preoperative radiograph demonstrating proximal bone loss. The femur has >3 cm of isthmus remaining (Type IIIa femoral defect). B: Femoral reconstruction with an 8-in extensively coated femoral implant.

metadiaphyseal bone damage with an intact diaphysis. Type III defects have significant metadiaphyseal damage with Type IIIA allowing >4 cm and Type IIIB allowing 19 mm.15 Additional contraindications to the use of an extensively coated stem are in patients who require a bowed 8- or 10-in stem with associated severe femoral torsional remodeling. Femoral remodeling in varus and retroversion is frequently observed at the time of revision, especially in loose cemented implants. The anterior femoral bow will dictate the amount of anteversion that can be obtained with the use of a bowed femoral stem. Because of the remodeling in retroversion, the stem frequently cannot be placed in an anatomic position. Component malposition with decreased femoral anteversion may result in recurrent posterior instability.

SURGICAL TECHNIQUE Exposure Similar to other surgical procedures, adequate preoperative planning is essential for a successful surgical outcome. Standard anteroposterior (AP) and lateral radiographs of the hip including all of the prosthesis and cement along with an AP pelvis are necessary. If the femoral component appears to be well fixed, a large distal cement mantle is present, or if there is significant femoral varus remodeling, an extended trochanteric

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osteotomy should be anticipated. It is imperative that an oscillating saw, pencil-tip burr, several wide osteotomes, trephines, Gigli saw, metal-cutting burr, and cerclage wires be available in the operative suite. The surgical approach in the revision setting may be directed by previous surgical incisions. In general, a posterior lateral approach is used to facilitate visualization of both the femur and the acetabulum. This approach will also allow extension both proximally and distally if needed. Once the femoral component is exposed, the stability of the implant is assessed. If the stem is grossly loose and the greater trochanter is not preventing extrication, the component is removed. However, if the trochanter is preventing component removal or if the stem is well fixed, an in situ extended trochanteric osteotomy is performed.

Bone Preparation It is imperative that the surgeon be able to concentrically ream the remaining diaphyseal bone. If the femur has undergone varus remodeling, an extended trochanteric osteotomy is required in order to avoid perforation of the lateral cortex. The femoral canal is sequentially reamed with straight reamers until cortical resistance is encountered. The femoral canal is underreamed by 0.5 mm in relation to the actual implant. Underreaming of the canal allows axial and rotation stability once the slightly larger implant is inserted. Throughout the reaming, the surgeon should be aware of the depth and the approximate location of the new stem. A minimum of 5 cm of diaphyseal bone, “scratch fit,” is required when utilizing a fully porous-coated stem. Alternative methods of reconstruction should be considered if this is not feasible. Once significant endosteal resistance is encountered with the reamers, a femoral trial can be placed. The hip can then be reduced and examined for stability. Provided the hip is stable, the amount of required femoral anteversion is marked. If an 8- or 10-in bowed stem is utilized, the bow of the femur and the prosthesis will control the ultimate amount of femoral anteversion. If the hip is not stable in this configuration, alternative methods of reconstruction such as a modular stem should be considered. When using an 8- or a 10-in bowed stem, the femur is reamed with flexible reamers. The bow of TABLE 25.1 Author(s)

a curved stem generally requires reaming line-to-line in order to safely insert the prosthesis. The surgeon must be cognizant while reaming to avoid anterior femoral perforation due to the anterior femoral bow along with the often hypertrophied posterior cortical bone.

Prosthesis Implantation The placement of a fully porous-coated stem in the revision situation is similar to that used during primary arthroplasty. A hole gauge should be used to verify that the manufacturing process has resulted in the appropriate distal femoral diameter (e.g., a 18-mm component should be able to pass through the 18.25-mm hole and not the 18.00-mm hole). The implant dimension should be compared to the last femoral reamer and should ideally be oversized by 0.5 mm. If the femoral component is relatively oversized, the femoral canal can be reamed an additional 0.5 mm to avoid femoral fracture during insertion. A series of gentle blows are used to seat the implant. The stem should advance with each strike of the mallet. Care must be taken to maintain the appropriate anteversion of the stem during the insertion. A prophylactic cerclage cable can be placed distal to the osteotomy site prior to insertion of the implant to avoid inadvertent fracture due to the relatively high hoop stresses at the level of the osteotomy.

RESULTS Femoral revision with the use of extensively coated stems has demonstrated excellent clinical and radiographic results (Table 25.1). The senior author reviewed 297 hips with a mean follow-up of 8.3 years (range, 5 to 14 years) in patients who underwent revision total hip arthroplasty using the extensively coated AML (DePuy, Warsaw, IN) prosthesis. All patients were evaluated radiographically and clinically at a minimum of 60 months. There were five patients (1.7%) who were revised due to aseptic femoral loosening while an additional two patients (0.7%) demonstrated unstable fibrous fixation. Therefore, the overall mechanical failure rate defined as the total number of stems showing radiographic evidence of an unstable interface

Outcome of Femoral Revision Hips

Follow-Up

Surgical Variables Outcome

Conclusion

Extensively Coated Revision Femoral Components Weeden and Paprosky16

170 hips

14.2 y (11–16 y)

Engh et al.17

26 hips

13.3 y

Moreland and Moreno18

137 hips 134 patients

9.3 y (5–16 y)

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Bone loss >10 cm below lesser trochanter

3.5% revision for aseptic femo- Extensively coated stems ral loosening should be used during 4.1% mechanical failure rate revision femoral surgery 89% survival at 10 y. For aseptic Extensively coated stems femoral revision can be used to bypass 15% aseptic femoral loosening severe proximal bone rate loss 4% revision rate of aseptic femo- Extensively coated stems ral loosening provide durable fixation 83% radiographic bone ingrowth

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TABLE 25.1

297

Outcome of Femoral Revision (Continued )

Author(s)

Hips

Follow-Up

Krishnamurthy et al.19

297 hips 297 patients

8.3 y (5–14 y)

Moreland and Bernstein20 Lawrence et al.21

175 patients

5y

83 hips 81 patients

9 y (5–13 y)

Surgical Variables Outcome

Conclusion

1.7% femoral revision for aseptic Diaphyseal fixation should loosening be used in femoral 2.4% mechanical failure rate revisions to avoid bone loss in the proximal metaphysis 96% component survival Extensively coated stems 83% bone ingrown provide durable fixation 10% femoral re-revision Extensively coated stems can 11% mechanical failure of femoprovide reliable fixation ral component during femoral revision

Cemented Revision Femoral Components McLaughlin and Harris22

35 hips 38 patients

10.8 y (5.8–16.6 y)

Calcar-replacing component

18% rate of aseptic femoral revision 32% rate of mechanical failure Mulroy and 43 hips 15.1 y (14.2–17.5 Second-generation 20% rate of aseptic femoral Second-generation cement Harris23 41 patients y) cement technique revision technique decreases the 26% rate of aseptic femoral prevalence of aseptic loosening femoral loosening 79 hips 47 hips with Second-generation 9.5% rate of femoral revision for Second-generation cement Katz et al.24 73 patients minimum 10-y cement technique aseptic loosening at 10 y technique improves follow-up 26.1% rate of radiographic femoclinical and radiographic ral failure at 10 y results. Cemented femoral revision demonstrates high rate of mechanical failure 45 hips 41 months First-generation 16% rate of femoral revision. Cemented re-revision demKavanagh and 45 patients cement technique 28% rate of radiographic onstrates poor clinical Fitzgerald25 loosening and radiographic results Pellicci et al.4 99 hips 8.1 y (5–12.5 y) First-generation 29% rate of mechanical failure Increased failure rate with cement technique longer follow-up of cemented stems Kavanagh et al.26 166 hips 4.5 y First-generation 44% radiographic aseptic The high incidence of 162 patients cement technique loosening radiographic signs of 9% rate of femoral revision loosening is of a concern Proximally Coated Revision Femoral Components Mulliken et al.8

52 hips 51 patients

4.6 y

Malkani et al.7

69 hips 69 patients

3y

Berry et al.6

375 hips

4.7 y

Woolson and Delaney9

25 hips

5.5 y

Monoblock titanium 10% femoral revision for aseptic Proximally porous-coated stem loosening; additional 14% stems in revisions with radiographically loose femoral bone loss show inadequate fixation Monoblock stem 8.7% femoral revision Proximally coated stems 29% mechanical failure do not provide reliable 82% 5 y survival fixation during revision surgery Monoblock stems 58% survivorship at 8 y for asep- Stable fixation with proxitic femoral revision mally coated femoral 20% survivorship for aseptic components can not be femoral loosening reliably achieved Monoblock titanium 20% rate of femoral re-revision Proximally porous-coated stem 45% mechanical failure femoral components should not be used in revision surgery

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or stems requiring revision surgery, divided by the total number of cases, was 2.4% at a mean follow-up of 8.3 years. The five hips that were revised for loosening were treated with a larger extensively coated stem. At the time of most recent follow-up, none of these patients were symptomatic, and all of the hips demonstrated bone ingrowth.19 A more recent evaluation of 170 femoral revisions treated with an extensively coated stem with average 14.2-year followup demonstrated continued clinical and radiographic success.16 Radiographic evidence of a bone-ingrown stem was present in 82% of the hips, stable fibrous fixation was present in 14% of the hips, and 4% of the hips were unstable. Six stems were revised to a larger, fully coated cementless implant. Therefore, the overall mechanical failure rate in this series was 4.1%, while the rate of aseptic femoral revision was 3.5%. Proximal femoral osteolysis was seen in 23% of femora but was limited to Gruen zones 1 and 7. No diaphyseal osteolysis was seen. Failure of fixation correlated highly with the extent of bone loss present at the time of surgery. Several other studies have demonstrated excellent clinical results with the use of an extensively coated stem. Lawrence et al. published the results of revision hip arthroplasty with the use of an extensively coated stem in 83 hips. At an average 9-year follow-up, only 10% of the femoral components were re-revised while the mechanical failure rate was 11%.21 Similarly, Moreland reviewed 137 femoral revisions treated with an extensively coated stem at an average follow-up of 9.3 years. Eighty-three percent of the implants met radiographic criteria for bone ingrowth while the revision rate for aseptic femoral loosening was 4%.18 The excellent results of extensively coated stems have prompted many surgeons to broaden the surgical indications for their use. Engh reviewed 26 hips at an average follow-up of 13.3 years in which an extensively coated stem >190 mm was used in association with severe bone loss (deficient bone >10 cm below lesser trochanter).17 Despite the hostile biologic environment, the survival rate at 10 years was 85% for aseptic femoral loosening and 89% for aseptic femoral revision. He concluded that extensively coated stems can be used to bypass severe proximal bone loss.

POSSIBLE PITFALLS OF EXTENSIVELY COATED STEMS Extensively porous-coated stems can provide reliable and predictable results if the appropriate indications are followed. However, as with most mechanical devices, there are potential complications associated with the use of a particular device. One concern that has been raised repeatedly with the use of extensively coated devices surrounds the concept of stress shielding. The implantation of a rigid stem in the femoral canal drastically alters the distribution of stress within the femur. When a rigid femoral stem with distal fixation is used, the stresses are directly transferred to the distal part of the femur, thereby shielding the proximal bone. The proximal bone responds according to Wolff law and results in atrophy of the unloaded portions.

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Various factors appear to be responsible for the phenomenon of stress shielding. Engh and Bobyn have shown that stem sizes >13.5 mm demonstrate a fivefold increase in stress shielding, while coating of the stem along its entire length or up to two thirds its length results in a twofold to fourfold increase in the incidence of stress shielding.27 Radiographic evidence of bone ingrowth into an extensively coated stem was also shown to cause a 2.5-fold increase in the proximal bone resorption. Although there is a great deal of concern about stress shielding in extensively coated stems, it must be emphasized that stressmedicated bone loss is only partially attributable to extensively porous-coated femoral implants. The stiffness of the bone relative to the implant appears to be a dominant risk factor for stress shielding. The bending stiffness of implants is proportional to the radius raised to the fourth power.4 Therefore, a small change in the stem size can have a marked impact on the stiffness of the stem. Similarly, titanium alloys have a lower modulus of elasticity compared to that of cobalt-chrome–based alloys. While the lower modulus of titanium may be beneficial, titanium is unable to be used as a material in extensively coated stems due to notch sensitivity created during the sintering process used to attach the beads. Stress shielding appears to occur within the first 2 years following component insertion and after that time does not appear to be progressive.20 Additionally, stress shielding does not appear to result in poorer clinical outcomes. Engh reviewed a series of 208 extensively porous-coated total hip arthroplasties at a mean 13.9-year follow-up (range, 2 to 18 years). He compared the outcome of 48 total hip arthroplasties that had radiographically evident stress shielding with 160 total hip arthroplasties that did not have radiographically visible stress shielding or that had less severe stress shielding. Stress shielding was more likely in women, patients with a low cortical index, and patients with larger stems. At the most recent follow-up, patients with stress shielding had a lower mean walking score than patients without stress shielding and less osteolysis. No patients with stress shielding had femoral loosening, implant fractures, or loss of porous coating. The revision rate was 13% (6 hips) among hips with stress shielding and 21% (33 hips) among hips without stress shielding. Fifteen-year survivorship was 93% among hips with stress shielding and 77% among hips without stress shielding. They concluded that stress shielding did not produce adverse consequences in these extensively porous-coated total hip arthroplasties.28 Extensively coated stems used in femoral revision rely upon distal fixation in the remaining intact isthmus. As a result, the proximal bone is rarely supportive, and bone ingrowth into the proximal coating is rare. Consequently, the implant is subjected to cantilever bending. An extensively coated cobalt-chromium implant has a relatively high modulus of elasticity, and physiologic loads are generally well below the endurance limit. However, in some situations, fatigue fracture of the stem may occur above the area of ingrowth. The senior author has observed this most commonly in extensively coated stems 12 mm.

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Additional concerns about the use of an extensively coated stem relate to the perceived difficulty in removing a well-fixed implant. The technique of an extended trochanteric osteotomy is very useful in the event that removal becomes necessary. Once the implant is exposed, the stem can be sectioned at the level of the cylindrical portion of the stem. Following extraction of the proximal piece, the distal portion can be removed with the use of trephines 0.5 mm larger than the stem.

SUMMARY The most important principle in femoral component revision surgery is to be able to achieve immediate and long-term stable fixation of the femoral component. In the presence of

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proximal femoral bone loss, which is frequently encountered in revision surgery, stable fixation is best achieved in the diaphyseal portion of the femur. The use of an extensively coated implant can achieve a tight diaphyseal fit and provide sufficient axial and rotational stability to allow bone ingrowth in most femoral defects. There are instances, however, where the isthmus is nonsupportive or torsional remodeling does not allow appropriate placement of an extensively coated device. In these circumstances, alternative reconstructive options should be chosen. The results of revision surgery utilizing extensively coated implants remain promising and are superior to historic cemented femoral revisions. Recent clinical and radiographic results show that bone ingrowth does occur in the majority of cases and that long-term stability can be obtained (Figs. 25-2–25-4).

FIGURE 25-2. A: Fifty-eight-year old patient with progressive proximal femoral osteolysis and a Type II femoral defect. B: One-year postoperative radiograph demonstrating stable fixation with a 6-in stem. Note the healing of the extended trochanteric osteotomy. C: Eight-year postoperative radiograph demonstrating stable fixation.

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FIGURE 25-3. A: Sixty-five-year old woman with aseptic femoral loosening and a Type IIIa femoral defect B: Six-month postoperative radiograph demonstrating stable fixation with a 10-in bowed extensively coated stem C: Thirteen-year radiograph demonstrating stable fixation. Note the extensive proximal stress shielding.

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FIGURE 25-4. A: Seventy-two-year old patient with aseptic loosening of a cemented femoral component with a resulting Type IIIa femoral defect. B: Postoperative radiograph demonstrating reconstruction with an 8-in bowed extensively coated stem. C: Postoperative radiograph demonstrating dislocation of the femoral head. Severe torsional remodeling was encountered at the time of index revision and appropriate anteversion was unable to be obtained. The patient eventually had a femoral re-revision with a modular stem that allowed appropriate femoral anteversion.

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REFERENCES 1. Mahomed NN, Barrett JA, Katz JN, et al. Rates and outcomes of primary and revision total hip replacement in the United States medicare population. J Bone Joint Surg Am 2003;85-A(1):27–32. 2. Weinstein JN., Dartmouth Atlas Working Group Dartmouth Atlas of Musculoskeletal Health Care. American Hospital Association Press; Chicago, Ill: 2000. 3. Malchau H, Herberts P, Soderman P, et al. Prognosis of total hip replacement. Scientific Exhibition Presented at the 67th Annual Meeting of the American Academy of Orthopaedic surgeons, 2000. 4. Pellicci PM, Wilson PD Jr, Sledge CB, et al. Long-term results of revision total hip replacement. A follow-up report. J Bone Joint Surg Am 1985;67(4):513–516. 5. Dohmae Y, Bechtold JE, Sherman RE, et al. Reduction in cement-bone interface shear strength between primary and revision arthroplasty. Clin Orthop Relat Res 1988;(236):214–220. 6. Berry DJ, Harmsen WS, Ilstrup D, et al. Survivorship of uncemented proximally porous-coated femoral components. Clin Orthop Relat Res 1995;(319):168–177. 7. Malkani AL, Lewallen DG, Cabanela ME, et al. Femoral component revision using an uncemented, proximally coated, long-stem prosthesis. J Arthroplasty 1996;11(4):411–418. 8. Mulliken BD, Rorabeck CH, Bourne RB. Uncemented revision total hip arthroplasty: a 4-to-6-year review. Clin Orthop Relat Res 1996;(325): 156–162. 9. Woolson ST, Delaney TJ. Failure of a proximally porous-coated femoral prosthesis in revision total hip arthroplasty. J Arthroplasty 1995;10(Suppl):S22–S28. 10. Bobyn JD, Pilliar RM, Cameron HU, et al. The optimum pore size for the fixation of porous-surfaced metal implants by the ingrowth of bone. Clin Orthop Relat Res 1980;(150):263–270. 11. Pilliar RM, Lee JM, Maniatopoulos C. Observations on the effect of movement on bone ingrowth into porous-surfaced implants. Clin Orthop Relat Res 1986;(208):108–113. 12. Paprosky WG, Bradford MS, Younger TI. Classification of bone defects in failed prostheses. Chir Organi Mov 1994;79(4):285–291. 13. Engh CA, Massin P, Suthers KE. Roentgenographic assessment of the biologic fixation of porous-surfaced femoral components. Clin Orthop Relat Res 1990;(257): 107–128. 14. Cook SD, Barrack RL, Thomas KA, et al. Tissue growth into porous primary and revision femoral stems. J Arthroplasty 1991;6(Suppl):S37–S46.

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15. Sporer SM, Paprosky WG. Revision total hip arthroplasty: the limits of fully coated stems. Clin Orthop Relat Res 2003;(417):203–209. 16. Weeden SH, Paprosky WG. Minimal 11-year follow-up of extensively porous-coated stems in femoral revision total hip arthroplasty. J Arthroplasty 2002;17(4 Suppl 1):134–137. 17. Engh CA Jr, Ellis TJ, Koralewicz LM, et al. Extensively porous-coated femoral revision for severe femoral bone loss: minimum 10-year followup. J Arthroplasty 2002;17(8):955–960. 18. Moreland JR, Moreno MA. Cementless femoral revision arthroplasty of the hip: minimum 5 years followup. Clin Orthop Relat Res 2001;(393):194–201. 19. Krishnamurthy AB, MacDonald SJ, Paprosky WG. 5- to 13-year follow-up study on cementless femoral components in revision surgery. J Arthroplasty 1997;12(8):839–847. 20. Moreland JR, Bernstein ML. Femoral revision hip arthroplasty with uncemented, porous-coated stems. Clin Orthop Relat Res 1995;(319):141–150. 21. Lawrence JM, Engh CA, Macalino GE, et al. Outcome of revision hip arthroplasty done without cement. J Bone Joint Surg Am 1994;76(7): 965–973. 22. McLaughlin JR, Harris WH. Revision of the femoral component of a total hip arthroplasty with the calcar-replacement femoral component. Results after a mean of 10.8 years postoperatively. J Bone Joint Surg Am 1996;78(3):331–339. 23. Mulroy WF, Harris WH. Revision total hip arthroplasty with use of so-called second-generation cementing techniques for aseptic loosening of the femoral component. A fifteen-year-average follow-up study. J Bone Joint Surg Am 1996;78(3):325–330. 24. Katz RP, Callaghan JJ, Sullivan PM, et al. Results of cemented femoral revision total hip arthroplasty using improved cementing techniques. Clin Orthop Relat Res 1995;(319):178–183. 25. Kavanagh BF, Fitzgerald RH Jr. Multiple revisions for failed total hip arthroplasty not associated with infection. J Bone Joint Surg Am 1987;69(8):1144–1149. 26. Kavanagh BF, Ilstrup DM, Fitzgerald RH Jr. Revision total hip arthroplasty. J Bone Joint Surg Am 1985;67(4):517–526. 27. Engh CA, Bobyn JD, Glassman AH. Porous-coated hip replacement. The factors governing bone ingrowth, stress shielding, and clinical results. J Bone Joint Surg Br 1987;69(1):45–55. 28. Engh CA Jr, Young AM, Engh CA Sr, et al. Clinical consequences of stress shielding after porous-coated total hip arthroplasty. Clin Orthop Relat Res 2003;(417):157–163.

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CHAPTER

26

Daniel J. Berry

Fluted Tapered Uncemented Femoral Stems

INTRODUCTION HOW FLUTED MODULAR TAPERED STEMS WORK INDICATIONS RESULTS TECHNIQUES AUTHOR’S PREFERRED TECHNIQUE POSTOPERATIVE CARE

INTRODUCTION Several decades ago, Heinz Wagner designed a fluted tapered uncemented grit-blasted titanium stem that is the progenitor of today’s modular fluted tapered uncemented stems. The stem was sufficiently successful to demonstrate the merits of a fluted tapered stem that gains axial and rotation stability in the diaphysis of the femur in revision hip surgery (Figs. 26-1 and 26-2). Modern fluted tapered stems are based on this concept but add modularity to the body of the stem to enhance clinical success and surgical versatility.1

HOW FLUTED MODULAR TAPERED STEMS WORK Fluted tapered modular stems work on the principle that the diaphysis of the femur can be milled to become a supportive tapered cone of bone. Engagement of the conical stem into the conically reamed femur provides axial stability of the implant. Sharp flutes provide rotational stability of the stem (Fig. 26-2). These stems are made of titanium or titanium alloys that have a grit-blasted surface. This surface texture promotes bone

ongrowth and has been demonstrated to provide long-term biologic implant fixation. Modern fluted tapered stems have a modular body, which has markedly enhanced the success of these implants. The femur is reamed distally to a supportive cone, and the distal conical fluted section of the stem is impacted into the femur until it is axially and rotationally completely stable. Subsequently, a proximal modular body, which provides optimal leg length and femoral offset, is then attached to the upper stem. The modularity of these systems allows the surgeon to simultaneously optimize complete seating of the implant into the tapered cone of bone and also restore hip biomechanics and hip stability. The modular junction of these stems is in the high stress subtrochanteric area of the femur2 (Fig. 26-3), and consequently, the junction is subject to metal fatigue failure. Fracture of a number of different devices at their junctions has been reported, and manufacturers have worked to optimize the strength of stems in this area to minimize the risk of this failure mode. Because fluted tapered stems are titanium, they are less stiff (for a specific stem diameter) than a fully porous-coated cobalt-chromium stem. Reduced modulus of elasticity has the theoretical advantage of reducing stress shielding of the proximal bone. Several reports on fluted tapered stems make note of bone reconstitution after reconstruction with these implants, although the local bone mass changes have not been rigorously quantitated.3–5 Some of the observed bone reconstitution may be due to bone recovery after removal of a failed implant, and some may be due to a fracture healing effect associated with extended osteotomies. Nevertheless, the bone remodeling pattern around these stems appears to be different than that observed around extensively porous-coated stems (Fig. 26-4). Possibly the combination of a lower modulus of elasticity in association with a grit-blasted surface (which may promote less intense bone ingrowth/ongrowth at the most distal aspect of the stem compared to extensively coated uncemented stems) explains some of the favorable bone remodeling around these implants.

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FIGURE 26-1. A: Radiograph of failed total hip arthroplasty with femoral component loosening. B: Radiograph after reconstruction with Wagner nonmodular body fluted tapered stem.

FIGURE 26-2. Wagner revision stem: the progenitor of modern fluted tapered grit-blasted titanium revision implants.

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FIGURE 26-3. Radiograph of fractured taper junction of modular body stem. The modular junction is in the high stress subtrochanteric area of the femur.

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FIGURE 26-4. A: Radiograph of failed total hip arthroplasty. B: Radiograph 4 years after revision demonstrating excellent bone remodeling. Cancellous intramedullary grafting was also performed at revision.

INDICATIONS Indications for use of these stems vary according to the surgeon’s philosophy. Some surgeons use these stems for most of their revisions, while others selectively use them in circumstances not ideal for other revision implants. Fluted tapered modular stems are particularly valuable when there is sufficient damage to the bone that good axial support for a long parallel-sided extensively porous-coated uncemented implant is not present (Figs. 26-5–26-7). Fluted tapered stems also may be used in Paprosky type IV bone defects in which the diaphyseal section of bone is too short to provide reliable bone ingrowth into an extensively coated parallel-sided stem. However, there must be sufficient bone present for the surgeon to create a supportive cone of bone; otherwise, the implant will subside (Figs. 26-8– 26-10). Fluted modular tapered stems are particularly valuable for treating periprosthetic femur fractures (see Chapter 32). Finally, some surgeons use fluted tapered stems when there is complete loss of proximal bone stock, much like a tumor prosthesis. It remains to be seen whether the modular tapers of these implants are sufficiently strong for use in this manner.

RESULTS The results of uncemented fluted tapered stems can be divided into results of modern modular body implants and nonmodular body Wagner-type implants. A number of studies

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reported reasonable rates of success with Wagner nonmodular body implants3,5–14 during the era in which revision hip arthroplasty was evolving. Bohm and Bischel7 reported only 6 of 129 stems required revision for any reason at 4.8 years. Bircher et al.6 reported a 10-year stem survivorship of 92% in 99 revisions. Most reported Wagner stem results would no longer be considered satisfactory because of relatively high rate of implant subsidence. Isacson et al.10 reported subsidence of >2 cm in 5 of 22 hips, and Bircher et al.6 noted that 6 of 99 stems subsided requiring early revision. High subsidence rates also occurred in other series.3,9,11 The Wagner implant had a high rate of subsidence because the surgeon did not always seat the implant fully into a reamed cone of distal bone. During that era, surgeons did not always understand the necessity of gaining absolutely rigid axial stability of the implant. Additionally, when these implants were implanted without an extended osteotomy, there was a tendency for the implant to seat with 3-point fixation, which provides less stability and bone contact than full engagement of the tapered cone of the implant into a tapered cone of femoral bone. A limited number of mostly short-term results of modern modular body fluted tapered stems are available. These results demonstrate high rates of implant fixation and much lower rates of subsidence compared to the Wagner stem.15,16 Kwong et al.15 reported on the modular body tapered fluted Link MP stem in 143 patients followed for 2 to 6 years. Seventy percent of patients had Mallory Type III bone loss. Only three hips required implant removal or exchange—one due to infection,

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FIGURE 26-5. A: Preoperative radiograph of failed total hip arthroplasty. Note deficient proximal bone and large canal diameter. B,C: Postoperative radiograph after revision with fluted tapered stem. Note that the femur has been milled to tapered cone.

FIGURE 26-6. A: Preoperative radiograph of failed total hip arthroplasty. Note markedly deficient proximal bone. B,C: Postoperative radiographs after revision with fluted tapered stem. Note that the femur has been milled to tapered cone and a corrective proximal osteotomy performed.

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FIGURE 26-7. A: Preoperative radiograph of failed total hip arthroplasty. Note large canal diameter. B,C: Postoperative radiographs after revision with fluted tapered stem.

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FIGURE 26-8. A: Preoperative radiograph of failed total hip arthroplasty. Note the very large canal diameter. B,C: Postoperative radiographs after revision with fluted tapered stem. Note that despite the large canal diameter, the femur has been milled to a tapered cone.

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FIGURE 26-9. A,B: Preoperative radiograph of failed total hip arthroplasty. Note the very large canal diameter. C,D: Postoperative radiographs after revision with fluted tapered stem. Note that despite the large canal diameter, the femur has been milled to a tapered cone.

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FIGURE 26-10. A,B: Preoperative radiograph of failed total hip arthroplasty. Note the large canal diameter. C,D: Postoperative radiographs after revision with fluted tapered stem. Note that despite the large canal diameter, the femur has been milled to a tapered cone.

one due to fracture of a small custom implant, and one due to inadequate body locking bolt assembly. No implants developed aseptic loosening, and the mean implant subsidence before stabilization was only 2.1 mm. Murphy and Rodriguez16 reported on 35 hips also revised with the Link MP implant and followed for a minimum of 2 years. Thirty-four of thirty-five hips developed radiographic evidence of osteointegration.

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TECHNIQUES Successful use of fluted tapered stems is predicated on reaming the diaphysis of the femur until a supportive cone of bone is created. The process of reaming the diaphysis of the femur to a supportive cone of bone is facilitated by extended greater trochanteric osteotomy. The extended trochanteric osteotomy

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CHAPTER 26 | FLUTED TAPERED UNCEMENTED FEMORAL STEMS

allows the surgeon to shape the diaphysis of the femur aggressively with straight fluted tapered reamers, thereby milling a supportive cone of bone. When an extended osteotomy is not performed, there is a tendency to undersize the implant because the reamers and the implant tend to “hang-up,” due to 3-point fixation of either the reamer or implant in the bowed femur. When preparing the femur for a fluted tapered stem, the surgeon needs to exercise caution to avoid anterior perforation of the femur (even if an extended trochanteric osteotomy has been performed), because the fluted tapered reamers are straight and the femur is bowed.

AUTHOR’S PREFERRED TECHNIQUE The femur is exposed by either a lateral or an anterior extended trochanteric osteotomy. If a long stem will be inserted, an anterior extended greater trochanteric osteotomy is preferred, because this allows the surgeon to ream the canal with the straight tapered reamers while avoiding distal anterior perforation of the bowed femur (Chapter 8) (Fig. 26-11). The failed femoral component is removed, and all cement is removed from the canal. Reamers of desired length are selected, and the femur is reamed sequentially with tapered reamers. Care is exercised to maintain the trajectory of the reamer straight down the femoral canal and to avoid distal anterior perforations (Fig. 26-11). The femur is reamed until good engagement of the reamer is obtained, and the surgeon can see that the femur has been reamed to a supportive cone of bone. Ideally, the supportive cone of bone should extend over 4 or 5 cm of the

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femoral canal. Insufficient reaming leads to insufficient support of the prosthesis and the potential for implant subsidence and failure. Excessive reaming leads to unnecessary bone loss, excessive weakening of the bone (and possible fracture), and may lead to distal perforation. When a long reamer is utilized, care to avoid distal anterior perforation is necessary, and a C-arm may be used to monitor progress of the reaming in selected cases. Next, trialing is performed to judge whether reaming has proceeded to the appropriate depth to allow placement of a proximal body. Most implant systems have different length proximal bodies which give the surgeon some flexibility in the necessary reaming depth. To facilitate placement of the trial proximal body, sometimes reaming of the proximal fragment of bone is necessary, and different implant systems provide different methods of performing this process. Once the surgeon has ascertained that satisfactory length/tension relationship has been reestablished, the reconstruction can proceed. The acetabular revision (if necessary) typically is completed at this point. If an extended osteotomy has been performed, a prophylactic cerclage cable or wire may be placed just distal to the osteotomy site to reduce risk of fracture during implant insertion when high hoop stresses are generated. The cable is partially tightened at this stage, but definitive tightening is delayed until the implant is partly inserted, to avoid crushing the weak bone. The prophylactic cable is important: Kwong et al.15 reported intraoperative fractures in 3 of 143 patients. A fluted tapered stem of appropriate length and size is brought onto the field and oriented properly. Most implants have a kink in the implant (proximal to the flutes) to allow fit to the femoral bow. The implant kink or bow

FIGURE 26-11. An anterior extended greater trochanteric osteotomy helps the surgeon avoid perforation of the anteriorly bowed femur during bone preparation with long straight tapered reamers. (With permission, Mayo Foundation.)

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should be placed so it is congruent with the anterior bow of the femur. The implant is driven carefully into the bone with multiple taps of moderate force. The implant is fully seated when it ceases to advance. Occasionally, a small crack will form in the femur, and this should be protected with at least one cable and if necessary, more. A trial proximal body is placed on the distal femoral component, and the surgeon chooses appropriate body size, length, offset, and anteversion. Next, the real femoral component body is brought onto the field and affixed to the distal body. The proximal body is placed in appropriate anteversion and must be locked to the distal body according to the manufacturer’s specifications. This portion of the procedure must be performed carefully to ensure that the modular junction is locked securely in anticipation of the high long-term stresses at this level. Finally, the femoral head is selected and impacted onto the proximal body, and the hip is reduced. If an extended osteotomy has been performed, it is reapproximated to its bed at this time. Frequently, the extended osteotomy fragment will not fit ideally against the remaining femoral bone, and a burr may be used to increase the radius or depth of the inner portion of the extended osteotomy bone fragment to allow it to seat against the implant and gain contact with the nonosteotomized portion of the femur.

POSTOPERATIVE CARE The patient usually is allowed either toe touch or partial weight bearing. Care should be taken to avoid excessively aggressive weight-bearing advancement: Kwong et al.15 reported early postoperative fractures associated with an episode of trauma, and Murphy and Rodriguez16 reported three supracondylar fractures in 54 hips. Weight bearing typically is advanced at 8 to 12 weeks postoperatively, depending on the magnitude of the reconstruction.

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REFERENCES 1. Berry DJ. Femoral revision: distal fixation with fluted, tapered grit-blasted stems. J Arthroplasty 2002;17:4:142–146. 2. Crowninshield RD, Maloney WJ, Wentz DH, et al. The role of proximal femoral support in stress development within hip prostheses. Clin Orthop Relat Res 2004;420:176–180. 3. Kolstad K, Adalberth G, Mallmin H, et al. The Wagner revision stem for severe osteolysis: 31 hips followed for 1.5–5 years. Acta Orthop Scand 1996;67:541. 4. Michelinakis E, Papapolychronlou T, Vafiadis J. The use of a cementless femoral component for the management of bone loss in revision hip arthroplasty. Bull Hosp Joint Dis 1996;55:28. 5. Rinaldi E, Marenghi P, Vaienti E. The Wagner prosthesis for femoral reconstruction by transfemoral approach. Chir Organi Mov 1994;79:353. 6. Bircher HP, Riede U, Luem M, et al. The value of the Wagner SL revision prosthesis for bridging large femoral defects. Orthopade 2001;30:294. 7. Bohm P, Bischel O. Femoral revision with the Wagner SL revision stem: evaluation of one hundred and twenty-nine revisions followed for a mean of 4.8 years. J Bone Joint Surg Am 2001;83A:1023–1031. 8. Boisgard S, Moreau PE, Tixier H, et al. Bone reconstruction, leg length discrepancy, and dislocation rate in 52 Wagner revision total hip arthroplasties at 44-month follow-up. Rev Chir Orthop Reparatrice Appar Mot 2001;87:147. 9. Grunig R, Morscher E, Ochsner PE. Three to 7-year results with the uncemented SL femoral revision prosthesis. Arch Orthop Trauma Surg 1997;116:187. 10. Isacson J, Stark A, Wallensten R. The Wagner revision prosthesis consistently restores femoral bone structure. Int Orthop 2000;24:139. 11. Ponziani L, Rollo G, Bungaro P, et al. Revision of the femoral prosthetic component according to the Wagner technique. Chir Organi Mov 1995;80:385. 12. Schenk RK, Wehrli U. Reaction of the bone to a cement-free SL femur revision prosthesis: histologic findings in an autopsy specimen 5-½ months after surgery. Orthopade 1989;18:454. 13. Suominen S, Santavirta S. Revision total hip arthroplasty in deficient proximal femur using a distal load-bearing prosthesis. Ann Chir Cynaecol 1996;85:253. 14. Wehrli U. Wagner revision of prosthesis stem. Z Unfallchir Versicherungsmed 1991;84:216. 15. Kwong LM, Miller AJ, Lubinus P. A modular distal fixation option for proximal bone loss in revision total hip arthroplasty: a 2- to 6-year followup study. J Arthroplasty 2003;18:94–97. 16. Murphy SB, Rodriguez J. Revision total hip arthroplasty with proximal bone loss. J Arthroplasty 2004;19:115–119.

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CHAPTER

27

James A. Browne Miguel E. Cabanela

Impaction Grafting of the Femur

OVERVIEW INDICATIONS AND CONTRAINDICATIONS BASIC SCIENCE TECHNIQUE CLINICAL RESULTS SUMMARY

OVERVIEW The incidence of revision total hip arthroplasty is increasing,1,2 and the number of patients requiring management of bone deficiencies during revision arthroplasty procedures has increased markedly.3 As hip replacement technology is applied to younger and more active patients, the multiply revised patient with poor femoral bone stock is becoming increasingly prevalent. Introduced into clinical practice over 20 years ago, the use of packed morselized bone in revision hip surgery to treat bone stock deficiency of the femur has become an important and accepted technique that offers some distinct advantages. Although the use of uncemented stems with diaphyseal engagement is the mainstay of revision femur work, impaction bone grafting is a valuable technique that offers the potential for restoration of bone stock and is particularly useful when faced with a large ectatic femoral metaphysis or diaphysis. The basic concept of femoral impaction grafting involves tight packing of contained cavitary defects with compressed particulate bone graft to support the subsequent insertion of a prosthetic implant. A femoral component is then cemented into a mechanically supportive neomedullary canal. While fairly straightforward in concept, this technique is technically challenging and requires meticulous execution to obtain a satisfactory outcome. Proper use of impaction bone grafting affords good initial support for an implant that otherwise would be inadequately supported by native bone.3 In addition to a stable construct, the potential exists to restore femoral bone stock for future reconstructions if required. Impaction grafting offers a potential biologic alternative to many of the other methods of dealing with bone loss.

INDICATIONS AND CONTRAINDICATIONS Femoral impaction bone grafting may be utilized in any patient undergoing revision of the femoral stem where restoration of femoral bone stock is considered advantageous, a scenario typically encountered in younger patients. This technique has been employed by some as a routine femoral revision technique, whereas others have limited it to specific revision scenarios. Impaction bone grafting is well suited in the case of a patulous femoral metaphysis or diaphysis that exceeds the diameter of available implants and precludes an adequate scratch fit for cementless fixation. When planning a cemented revision stem, impaction bone grafting is useful when a smooth endosteal canal is encountered, and little cancellous bone remains for mechanical interlocking fixation. The presence of active infection is an absolute contraindication to impaction bone grafting. However, despite theoretical concerns about introducing bone graft in a previously infected host, clinical studies have demonstrated success when bone grafts are required for a subsequent reconstruction of a previously infected joint.4,5 English et al. reported on 53 patients who underwent impaction grafting of the femur during the second stage of a two-stage revision for infection and demonstrated 93% success rate in the elimination of infection at a mean follow-up of 53 months, results comparable to other techniques that do not use allograft bone.5 Relative contraindications include old age or extensive medical problems that would place the patient at jeopardy for complications with a long operation. Although meshes or cortical struts may be used to reconstruct the femoral tube, extensive or severe cortical defects and abnormally thin cortical bone may argue against this technique when other options are feasible. Diaphyseal bone fracture is a common serious complication of this procedure and speaks to the importance of proper patient selection.

BASIC SCIENCE Bone Graft The original description of impaction grafting involved the use of morselized cancellous bone.6 Morselized cancellous bone was felt to be preferable to cortical bone 313

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given the more rapid revascularization, efficient osteogenesis, and early incorporation with host bone,7 and this remains the benchmark for modern impaction grafting techniques.3 However, despite slower rates of revascularization, morselized cortical grafts have theoretical advantages in providing increased initial structural support.8,9 Kligman et al. have reported decreased implant migration and improved clinical outcomes with morselized cortical graft in both femoral and acetabular reconstructions.10,11 The impacted graft may be either autograft or allograft. Autograft bone is osteogenic, osteoconductive, and osteoinductive, all of the characteristics required to stimulate new bone formation. Several experimental and clinical studies have confirmed its superiority to allograft, which is primarily osteoconductive and functions primarily as a scaffold for new bone formation.3,8 One of the earliest reports of a successful use of this technique involved the use of posterior iliac crest autograft.12 However, for practical reasons, allograft is used widely in clinical practice. The quantity of bone required to reconstruct large defects often exceeds the amount of autograft that is reasonably available. The risk of donor site morbidity is also avoided when using allograft. Femoral head allograft is the most common source of graft in our practice at the present time. The processing of allograft may be another important factor in the outcome of impaction grafting. While fresh frozen bone is commonly used, preservation of allografts may be performed by freezing, freeze-drying, or irradiating the bone. Processing of the graft significantly reduces the immune response to the graft and speeds bony incorporation by eliminating bone marrow cells and fat.8,13,14 It also reduces the risk of disease transmission; cases have been reported of HIV and hepatitis C transmission with nonprocessed bone allograft.15,16 However, processed bone has decreased mechanical properties.17,18 Increased subsidence of the stem and lack of radiographic evidence of bone incorporation have been anecdotally reported in association with irradiated bone.19 Clinically, fresh frozen bone is currently associated with the best long-term results.20 However, given the variability in reported results, a recent Cochrane database review found no level 1 evidence upon which to draw conclusions about the clinical effectiveness of fresh frozen compared to processed bone.21 The densely packed bone graft must provide mechanical support for a femoral implant. The general consensus is that the particles should be as large as practical to ensure stability and cement penetration.22–24 The optimal size for graft particles for acetabular grafting has been reported to be between 7 and 10 mm, larger than the 2 to 5 mm graft particles obtained from most standard bone mills.25–27 The reverse reaming technique of a bone slurry graft has been shown to be inferior with mechanical testing.28 On the femoral side, the largest practical size for distal packing is thought to be between 3 and 5 mm,22 whereas the proximal quarter of the canal may be packed with larger 8 to 10 mm chips.29 Standard bone mills typically produce particles

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between 2 and 5 mm; a rongeur or bone nibbler produce a more optimal-size graft. A fine-milled bone slurry lacks the mechanical properties required for adequate impaction and should be avoided. The optimal uniformity of particle size and the desired amount of compaction remains a matter of debate. In their original paper, Gie et al.30 recommended “vigorous impaction” for grafting of the femur, although this is difficult to quantify. While using a range of bone chip sizes and tightly packing the graft improves the initial stability, it also decreases graft permeability (by filling in the voids between large particles with smaller particles), potentially leading to reduced new bone ingrowth31,32 and less cement penetration.22,24 Preparation of the graft also influences the mechanical properties of the construct. Prewashing of the bone to remove fat and marrow fluid has been shown to allow the production of a stronger compacted graft that is more resistant to shear, presumably by decreasing the presence of incompressible fluid and interparticle lubricants.23,24,33 The biologic effects of removing potentially positive growth factors and negative immunogenic factors through rinsing are less clear. Various materials have been used to augment the cancellous bone graft in an attempt to improve initial stability. Ceramic particles have been mixed in with the morselized bone with good short-term results.34 As a complete alternative to allograft, initial in vitro results of compacted porous titanium particles are also encouraging.35 In addition to structural augmentation, biological enhancement and modulation has also been explored with the addition of marrowderived autogenous progenitor cells,36 bone morphogenic proteins,32,37 and bisphosphonates37 with mixed results.38–40 At this time, the role of adjuvants in impaction grafting remains unclear.

Graft Incorporation and Regeneration The biologic fate of impacted bone grafts in total hip arthroplasty is largely unknown. The difficulty in interpreting the status of the bone graft on radiographs,41 combined with the lack of large numbers of autopsy retrievals, means that we have limited definitive scientific evidence on the long-term histologic status of these grafts.3 The long-term success of impaction grafting, and the ability to achieve the major benefit of restoration of bone stock, is dependent upon the biologic interplay between the host bone and the graft.22 Following bone grafting, an early phase of inflammation occurs, followed by revascularization.26,42 Positron emission tomography (PET) scans have suggested increased blood flow and bone formation adjacent to the allograft as early as 8 days postoperatively.43 Animal models have confirmed that graft resorption, woven bone deposition, and subsequent remodeling occurs over a period of several weeks, leading to almost complete incorporation at 12 weeks and full consolidation and revascularization by 24 weeks.44 The incorporation of impacted graft has been likened to the fracture healing process with endochondral ossification observed in the graft bed.44,45

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Biopsies taken at the time of revision surgery and cadaveric specimens have given us some insight into the longer term fate of the impacted bone. Consistent evidence of living bone and osteoid formation in the graft has been reported at 4 months, although a significant proportion of the allograft appears to remain necrotic several years postoperatively.32,45 Biopsies from human specimens have suggested that the graft regenerates by 15 months,46 with complete incorporation and replacement with viable bone seen several years out from surgery.27,68 However, in a study of eight femoral biopsies taken at revision surgery and six femurs obtained at autopsy, Linder found a more inconsistent and variable spectrum of bone healing and regeneration.41 The most typical histologic pattern, seen in over half of specimens, was one of varied trabecular incorporation including fibrous tissue and necrotic bone. Variable amounts of graft bone were commonly seen to have been embedded into dense fibrous tissue, resulting in a composite tissue that could potentially bear load and support the prosthesis. The key biologic processes appeared to occur early given that the histologic appearance did not appear to differ or deteriorate after 6 months.41 There was poor correlation between the histologic findings and the radiographic images. Ullmark and Obrant reported a prospective series of 19 patients treated with impaction femoral grafting during revision surgery who subsequently had percutaneous biopsies taken from Gruen zones 1 and 2 at 1 to 48 months postoperatively.45 Fibrous tissue invasion of the graft and new bone formation occurred from the periphery of the graft and were complete by 11 months. The innermost layer of the graft bed consisted of dead trabecular graft with fibrous invasion but without the evidence of graft resorption. Although healing was more complete by 48 months, areas of necrotic graft persisted. On the acetabular side, van der Donk et al.42 also found variable amounts of unincorporated graft in their examination of 24 biopsies of acetabular impaction bone grafts. Incorporation was seen in 30% of the graft by 6 months and 90% by 10 years. Areas of loose fibrous stroma on which new bone had formed were also noted. Advanced imaging studies have also given some longer term evidence that bone regeneration within the graft reliably occurs. Ullmark et al. used PET scans to study five patients treated with femoral impaction grafting at 6 years postoperatively and found that the bone metabolism had normalized compared to native bone.47 On the whole, these studies suggest a reliable and durable biological outcome including bone regeneration with optimal application of this technique. Mechanical loading of the graft appears to stimulate incorporation and has been cited as a principal cause for the success of this procedure.32,48,49 Although the effect of load on graft incorporation has been suggested, its exact influence on the fate of the graft is difficult to demonstrate. In a recent goat model utilizing a subcutaneous pressure implant, van der Donk et al.50 found that loading of impacted graft led to only a modest increase in the area of active incorporating bone and did not affect the formation of a new bony structure.

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TECHNIQUE The technique of impaction femoral grafting with cementing of the component was introduced into clinical practice in the late 1980s. Current techniques have been popularized by Gie et al.29,30 and Slooff et al.51 The surgical technique is both demanding and critically important in avoiding complications and ensuring long-term survival of the reconstruction. Preoperative planning includes the exclusion of infection and the assessment of bone deficiencies. Templating is performed to estimate the length of stem required to bypass any cortical or significant endosteal defects. The common practice of bypassing cortical defects by at least two diaphyseal diameters is recommended. The femur may be approached through an anterior, a posterior, or a transtrochanteric approach. The failed femoral component is removed along with cement and debris. Thorough debridement of the endosteal canal is important to ensure future incorporation of the impacted graft. A distal well-fixed cement column may be left in place as a distal plug of the column of bone graft. An extended trochanteric osteotomy may be used without compromising the results so long as the osteotomy is repaired adequately with cables. The femur is assessed for bone deficiencies. Contained defects are a prerequisite to impaction grafting; uncontained defects may be converted to contained defects with the use of mesh. Malleable meshes may be secured with monofilament wire or cables. Allograft struts have also been employed to create a continuous femoral tube. Cerclage wires or cables should be employed prophylactically when the cortical bone is thin. Although the use of cortical onlay allograft struts may reduce the risk of fracture, care must be taken to avoid excessive soft tissue dissection and stripping, as this may compromise blood supply to the bone and impair subsequent revascularization.3 Occlusion of the canal is required 2 to 3 cm below the most distal cavitary deficiency or below the distal tip of the implant to be used. In our practice, the cancellous bone graft is prepared in fragments measuring 4 to 6 mm in size. The authors routinely use allograft from fresh frozen femoral heads. Using a centering guide or guidewire to ensure a uniform bone mantle, progressively sized cylindrical packers are used, starting distally in the bottom of the canal, to compress the morselized bone.3 Once the canal is two-thirds full, tamps of the same shape as the prosthesis are used to shape the proximal femoral endosteal cavity and create an endosteal canal. At this time, careful attention must be paid to the version of the tamp (Fig. 27-1A,B,C). Vigorous impacting is required to provide rotational and axial stability for the stem, although excessive force may lead to fracture. The tamps are slightly oversized when compared to the actual implant to allow for a cement mantle. Trial reduction may be performed when the stability of the tamp is adequate. Following final preparation and drying of the neomedullary canal, cementation is performed in standard retrograde fashion. Pressurization is performed with the use of a flexible femoral seal. Maintaining pressurization of the cement, the implant is slowly inserted to the predetermined position and held as the cement polymerizes.

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FIGURE 27-1. Schematic representation of the technique of femoral impaction grafting. A. Retrograde cancellous bone packing of canal. B. Reshaping the femoral canal with temp. C. Attention to ramp version. (Adapted from Oakes DA, Cabanella ME. Impaction bone grafting for revision hip arthroplasty: biology and clinical applications. JAAOS 2006;14:624, Copyrighted and used with permission of Mayo Foundation for Medical Education and Research, all rights reserved.)

CLINICAL RESULTS Intermediate-term results have shown impaction grafting to be a reliable and durable technique for femoral revision (Table 27.1). When done well, the results of impaction grafting are excellent with 10-year survivorship in excess of 90%.52 Analysis of 1,305 femoral revisions in Sweden revealed

FIGURE 27-2. Anteroposterior radiograph of the right hip of a 59-year-old woman taken 19 years after a cemented arthroplasty. Note the large cavitary femoral deficiencies.

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all-cause survivorship over 94% at 15 years using impaction grafting, demonstrating the predictable nature of the procedure (Figs. 27-2–27-4).60 Intraoperative fractures are relatively common and were a frequent complication during the early experience with impaction grafting. Halliday et al.52 reported a 4% intraoperative fracture rate in 226 hips, although the literature contains a series where the incidence has exceeded 20%.58 Most intraoperative fractures are related to technique and are potentially avoidable. Nondisplaced cracks may be unrecognized at the time of surgery and typically occur during the seating of the trial rasps. Cortical windows or perforations that occur during cement removal also predispose to fracture.61 Cortical strut allografts and/or cerclage wires are usually sufficient for treatment; when recognized and remedied, these fractures do not appear to compromise the outcome of the reconstruction.56 On the other hand, postoperative femoral shaft fractures are a serious and disturbing complication. These fractures tend to occur at the tip of the stem and are not typically associated with prosthetic loosening.53 A recent review of the literature suggested a reported prevalence of 4% (64 fractures after 1,570 reconstructions).56 Fractures are often observed at a location of a segmental bone defect that had been present or created at surgery,20,61 leading some groups to use long stems to bypass cortical defects. Although the use of a long stem does not appear to completely eliminate postoperative fractures,56 this technique is beneficial and recommended. Unlike intraoperative fractures, postoperative fractures are more likely to be a reflection of the quality of host bone than the surgical technique. Slight early subsidence of the femoral stem is common when using tapered wedge-shaped stems and does not appear to portend failure. Although other stem designs have been used successfully in clinical practice, the double-tapered, highly polished, collarless implant is felt by many (including the original proponents of this technique) to be beneficial in loading the graft and allowing for controlled subsidence.30 Schreurs et al.20 reported on 33 hips treated with this type of implant at a mean of 10.4 years and found that only one third of patients

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FIGURE 27-3.

317

Anteroposterior and lateral radiographs of the same patient 2 months after revision with femoral impaction cancellous allograft.

FIGURE 27-4. A and B: Anteroposterior and lateral radiographs of the same patient 15 years after revision. Excellent clinical result. Note femoral bone remodeling.

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TABLE 27.1

Clinical Results of Impaction Grafting of the Femur at Intermediate-Term Follow-up

Study

Number of hips

Halliday et al.52 Cabanela et al.53 Schreurs et al.20 Mikhail et al.54 Ullmark et al.55

226 57 33 43 56

Sierra et al.56

Survivorship (any femoral reoperation) (%)

Survivorship (aseptic femoral loosening) (%)

Implant

Follow-up

Post-op femoral shaft fractures (%)

10–11 y Mean 6.3 y Mean 10.4 y 5–7 y Median 5.3 y

4 10.5 9 5 7

90.5 89 91 95 87–89a

99.1 100 100 100 96

42

Collarless, polished, tapered Collarless, polished, tapered Collarless, polished, tapered Collarless, polished, tapered Collared, matte finish, not tapered Long stem (>220 mm)

Mean 7.5 y

5

82

Mahoney et al.57 Leopold et al.58 Wraighte et al.59

43 29 75

Collarless, polished, tapered Precoated, collared, straight Collarless, polished, tapered

Mean 4.7 y Mean 5.3 y Mean 10.5 y

2 0 3

97 92 92

Ornstein et al.60

1,305

Collarless, polished, tapered

Up to 15 y

1.3

94

Two failures for aseptic loosening at 5 and 11 yb 97 92 One revision for aseptic looseningb 99.1

aDepending bKaplan

upon prosthetic implant. Meier survival analysis not performed for aseptic loosening.

had no migration of the stem. In two thirds of their patients, the stem had migrated an average of 3 mm within the cement by the time of final review. No patients were seen to have had migration of the cement mantle relative to the bone. No stems were revised for loosening in this series, and no relationship between the observed subsidence and the clinical outcome was seen. Radiolucent lines more than 50% of the stem have been correlated with stem subsidence and thigh pain in some series.62 Massive subsidence (>10 mm) has been reported63 although most series show this to occur relatively infrequently. More moderate subsidence of 5 mm or more has been reported in 14% to 33% of patients.52,54,64 Marked subsidence has been thought to be associated with the fracture of the cement mantle65 and to be predictive of early failure.66 However, Wraighte et al.59 recently reported on 75 femoral impaction graftings at a mean of 10.5 years and found that migration of the stem within the cement mantle, even in excess of 10 mm, was not found to be related to the long-term outcome or complications. The majority of stem subsidence appears to occur within the first 6 months20; aseptic loosening, similarly, occurs early in the first few years. However, a stem that continues to migrate is loose by definition, and the exact distinction between aseptic loosening and subsidence is often unclear. An RSA study of 15 impaction graftings using Exeter stems with good clinical outcomes found that 3 were stable between 2 and 5 years postoperatively, 11 showed minimal migration, and 1 was migrating continuously but remained asymptomatic.67

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SUMMARY Impaction allografting of the femur is appealing in its ability to restore bone stock. This approach is particularly useful when the surgeon is faced with a large ectatic femoral metaphysis or diaphysis that precludes cementless fixation. Reported clinical results support this technique as a reliable and predictable solution in the challenging scenario of femoral bone loss. However, the procedure is time consuming and unquestionably challenging, and technical problems have been reported. Problems with postoperative fractures and subsidence are recognized with this technique. Questions about the long-term fate of the allograft and clinical outcomes remain largely unanswered at the present time.

REFERENCES 1. Kurtz S, Ong K, Lau E, et al. Projections of primary and revision hip and knee arthroplasty in the United States from 2005 to 2030. J Bone Joint Surg Am 2007;89:780–785. 2. Iorio R, Robb WJ, Healy WL, et al. Orthopaedic surgeon workforce and volume assessment for total hip and knee replacement in the United States: preparing for an epidemic. J Bone Joint Surg Am 2008;90(7):1598–1605. 3. Oakes DA, Cabanela ME. Impaction bone grafting for revision hip arthroplasty: biology and clinical applications. J Am Acad Orthop Surg 2006;14(11):620–628. 4. Berry DJ, Chandler HP, Reilly DT. The use of bone allografts in two-stage reconstruction after failure of hip replacements due to infection. J Bone Joint Surg Am 1991;73(10):1460–1468.

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5. English H, Timperley AJ, Dunlop D, et al. Impaction grafting of the femur in two-stage revision for infected total hip replacement. J Bone Joint Surg Br 2002;84(5):700–705. 6. Slooff TJ, Huiskes R, van Horn J, et al. Bone grafting in total hip replacement for acetabular protrusion. Acta Orthop Scand 1984;55(6):593–596. 7. Slooff TJ, Schimmel JW, Buma P. Cemented fixation with bone grafts. Orthop Clin North Am 1993;24(4):667–677. 8. Goldberg VM. Selection of bone grafts for revision total hip arthroplasty. Clin Orthop Relat Res 2000;(381):68–76. 9. Kligman M, Rotem A, Roffman M. Cancellous and cortical morselized allograft in revision total hip replacement: a biomechanical study of implant stability. J Biomech 2003;36(6):797–802. 10. Kligman M, Con V, Roffman M. Cortical and cancellous morselized allograft in revision total hip replacement. Clin Orthop Relat Res 2002;(401):139–148. 11. Kligman M, Padgett DE, Vered R, et al. Cortical and cancellous morselized allograft in acetabular revision total hip replacement: minimum 5-year follow-up. J Arthroplasty 2003;18(7):907–913. 12. Pusso R, Muscolo D, Piccaluga F. Reconstrucciones de la extremidad superior del fémur. Rev Asoc Arg Ortop Y Traumatol 1991;56:378–387. 13. van der Donk S, Weernink T, Buma P, et al. Rinsing morselized allografts improves bone and tissue in growth. Clin Orthop Relat Res 2003;(408):302–310. 14. Burwell RG. Studies in the transplantation of bone. V. The capacity of fresh and treated homografts of bone to evoke transplantation immunity. J Bone Joint Surg Br 1963;45-B:386–401. 15. Simonds RJ, Holmberg SD, Hurwitz RL, et al. Transmission of human immunodeficiency virus type 1 from a seronegative organ and tissue donor. N Engl J Med 1992;326(11):726–732. 16. Conrad EU, Gretch DR, Obermeyer KR, et al. Transmission of the hepatitis-C virus by tissue transplantation. J Bone Joint Surg Am 1995;77(2):214–224. 17. Pelker RR, Friedlaender GE, Markham TC. Biomechanical properties of bone allografts. Clin Orthop Relat Res 1983;(174):54–57. 18. Pelker RR, Friedlaender GE, Markham TC, et al. Effects of freezing and freeze-drying on the biomechanical properties of rat bone. J Orthop Res 1984;1(4):405–411. 19. Hassaballa M, Mehendale S, Poniatowski S, et al. Subsidence of the stem after impaction bone grafting for revision hip replacement using irradiated bone. J Bone Joint Surg Br 2009;91(1):37–43. 20. Schreurs BW, Arts JJ, Verdonschot N, et al. Femoral component revision with use of impaction bone-grafting and a cemented polished stem. J Bone Joint Surg Am 2005;87(11):2499–2507. 21. Board TN, Brunskill S, Doree C, et al. Processed versus fresh frozen bone for impaction bone grafting in revision hip arthroplasty. Cochrane Database Syst Rev 2009;(4):CD006351. 22. Toms AD, Barker RL, Jones RS, et al. Impaction bone-grafting in revision joint replacement surgery. J Bone Joint Surg Am 2004;86-A(9):2050– 2060. 23. Ullmark G. Bigger size and defatting of bone chips will increase cup stability. Arch Orthop Trauma Surg 2000;120(7–8):445–447. 24. Arts JJ, Verdonschot N, Buma P, et al. Larger bone graft size and washing of bone grafts prior to impaction enhances the initial stability of cemented cups: experiments using a synthetic acetabular model. Acta Orthop 2006;77(2):227–233. 25. Schreurs BW, Gardeniers JW, Slooff TJ. Acetabular reconstruction with bone impaction grafting: 20 years of experience. Instr Course Lect 2001;50:221–228. 26. Schreurs BW, Slooff TJ, Buma P, et al. Basic science of bone impaction grafting. Instr Course Lect 2001;50:211–220. 27. Bolder SB, Schreurs BW, Verdonschot N, et al. Particle size of bone graft and method of impaction affect initial stability of cemented cups: human cadaveric and synthetic pelvic specimen studies. Acta Orthop Scand 2003;74(6):652–657. 28. Bolder SB, Verdonschot N, Schreurs BW. Technical factors affecting cup stability in bone impaction grafting. Proc Inst Mech Eng H 2007;221(1):81–86.

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29. Blake SM, Gie GA, Howell JR. Impaction Grafting of the Femur. In: Brown TE, Cui Q, Mihalko WM, et al., eds. Arthritis and Arthroplasty: The Hip. Philadelphia, PA: Saunders Elsevier; 2009:337–353. 30. Gie GA, Linder L, Ling RS, et al. Impacted cancellous allografts and cement for revision total hip arthroplasty. J Bone Joint Surg Br 1993;75(1):14–21. 31. Tägil M, Aspenberg P. Impaction of cancellous bone grafts impairs osteoconduction in titanium chambers. Clin Orthop Relat Res 1998;(352): 231–238. 32. Tägil M. The morselized and impacted bone graft. Animal experiments on proteins, impaction and load. Acta Orthop Scand Suppl 2000;290: 1–40. 33. Dunlop DG, Brewster NT, Madabhushi SP, et al. Techniques to improve the shear strength of impacted bone graft: the effect of particle size and washing of the graft. J Bone Joint Surg Am 2003;85-A(4):639–646. 34. Blom AW, Wylde V, Livesey C, et al. Impaction bone grafting of the acetabulum at hip revision using a mix of bone chips and a biphasic porous ceramic bone graft substitute. Acta Orthop 2009;80(2):150–154. 35. Aquarius R, Walschot L, Buma P, et al. In vitro testing of femoral impaction grafting with porous titanium particles: a pilot study. Clin Orthop Relat Res 2009;467(6):1538–45. Epub 2009 Jan 13. 36. Tilley S, Bolland BJ, Partridge K, et al. Taking tissue-engineering principles into theater: augmentation of impacted allograft with human bone marrow stromal cells. Regen Med 2006;1(5):685–692. 37. Jeppsson C, Astrand J, Tägil M, et al. A combination of bisphosphonate and BMP additives in impacted bone allografts. Acta Orthop Scand 2003;74(4):483–489. 38. Tägil M, Jeppsson C, Wang JS, et al. No augmentation of morselized and impacted bone graft by OP-1 in a weight-bearing model. Acta Orthop Scand 2003;74(6):742–748. 39. Jakobsen T, Baas J, Bechtold JE, et al. Soaking morselized allograft in bisphosphonate can impair implant fixation. Clin Orthop Relat Res 2007;463:195–201. 40. Hannink G, Schreurs BW, Buma P. No positive effects of OP-1 device on the incorporation of impacted graft materials after 8 weeks: a bone chamber study in goats. Acta Orthop 2007;78(4):551–558. 41. Linder L. Cancellous impaction grafting in the human femur: histological and radiographic observations in 6 autopsy femurs and 8 biopsies. Acta Orthop Scand 2000;71(6):543–552. 42. van der Donk S, Buma P, Slooff TJ, et al. Incorporation of morselized bone grafts: a study of 24 acetabular biopsy specimens. Clin Orthop Relat Res 2002;(396):131–141. 43. Sörensen J, Ullmark G, Långström B, et al. Rapid bone and blood flow formation in impacted morselized allografts: positron emission tomography (PET) studies on allografts in 5 femoral component revisions of total hip arthroplasty. Acta Orthop Scand 2003;74(6):633–643. 44. Schimmel JW, Buma P, Versleyen D, et al. Acetabular reconstruction with impacted morselized cancellous allografts in cemented hip arthroplasty: a histological and biomechanical study on the goat. J Arthroplasty 1998;13(4):438–448. 45. Ullmark G, Obrant KJ. Histology of impacted bone-graft incorporation. J Arthroplasty 2002;17(2):150–157. 46. Buma P, Lamerigts N, Schreurs BW, et al. Impacted graft incorporation after cemented acetabular revision. Histological evaluation in 8 patients. Acta Orthop Scand 1996;67:536–540. 47. Ullmark G, Sörensen J, Långström B, et al. Bone regeneration 6 years after impaction bone grafting: a PET analysis. Acta Orthop 2007;78(2): 201–205. 48. Wang JS, Tägil M, Aspenberg P. Load-bearing increases new bone formation in impacted and morselized allografts. Clin Orthop Relat Res 2000;(378):274–281. 49. Schreurs BW, Buma P, Huiskes R, et al. Morsellized allografts for fixation of the hip prosthesis femoral component. A mechanical and histological study in the goat. Acta Orthop Scand 1994;65(3):267–275. 50. van der Donk S, Buma P, Verdonschot N, et al. Effect of load on the early incorporation of impacted morsellized allografts. Biomaterials 2002;23(1):297–303.

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51. Slooff TJ, Buma P, Schreurs BW, et al. Acetabular and femoral reconstruction with impacted graft and cement. Clin Orthop Relat Res. 1996;(324):108–115. 52. Halliday BR, English HW, Timperley AJ, et al. Femoral impaction grafting with cement in revision total hip replacement. Evolution of the technique and results. J Bone Joint Surg Br 2003;85(6):809–817. 53. Cabanela ME, Trousdale RT, Berry DJ. Impacted cancellous graft plus cement in hip revision. Clin Orthop Relat Res 2003;417:175–182. 54. Mikhail WE, Wretenberg PF, Weidenhielm LR, et al. Complex cemented revision using polished stem and morselized allograft. Minimum 5-years’ follow-up. Arch Orthop Trauma Surg 1999;119:288–291. 55. Ullmark G, Hallin G, Nilsson O. Impacted corticocancellous allografts and cement for revision of the femur component in total hip arthroplasty. J Arthroplasty 2002;17:140–149. 56. Sierra RJ, Charity J, Tsiridis E, et al. The use of long cemented stems for femoral impaction grafting in revision total hip arthroplasty. J Bone Joint Surg Am 2008;90(6):1330–1336. 57. Mahoney CR, Fehringer EV, Kopjar B, et al. Femoral revision with impaction grafting and a collarless, polished, tapered stem. Clin Orthop Relat Res 2005;(432):181–187. 58. Leopold SS, Berger RA, Rosenberg AG, et al. Impaction allografting with cement for revision of the femoral component. A minimum four-year follow-up study with use of a precoated femoral stem. J Bone Joint Surg Am 1999;81(8):1080–1092. 59. Wraighte PJ, Howard PW. Femoral impaction bone allografting with an Exeter cemented collarless, polished, tapered stem in revision hip replacement: a mean follow-up of 10.5 years. J Bone Joint Surg Br 2008;90(8):1000–1004. 60. Ornstein E, Linder L, Ranstam J, et al. Femoral impaction bone grafting with the Exeter stem—the Swedish experience: survivorship analysis of

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61.

62.

63. 64.

65.

66.

67.

68.

1305 revisions performed between 1989 and 2002. J Bone Joint Surg Br 2009;91(4):441–446. Ornstein E, Atroshi I, Franzén H, et al. Early complications after one hundred and forty-four consecutive hip revisions with impacted morselized allograft bone and cement. J Bone Joint Surg Am 2002;84A(8):1323–1328. Kligman M, Con V, Roffman M. Cortical and cancellous morselized allograft in revision total hip replacement. Clin Orthop Relat Res 2002;(401):139–148. Eldridge JD, Smith EJ, Hubble MJ, et al. Massive early subsidence following femoral impaction grafting. J Arthroplasty 1997;12:535–540. van Biezen FC, ten Have BL, Verhaar JA. Impaction bone-grafting of severely defective femora in revision total hip surgery: 21 hips followed for 41–85 months. Acta Orthop Scand 2000;71:135–142. Masterson EL, Masri BA, Duncan CP. The cement mantle in the Exeter impaction allografting technique: a cause for concern. J Arthroplasty 1997;12:759–764. Walker PS, Mai SF, Cobb AG, et al. Prediction of clinical outcome of THR from migration measurements on standard radiographs: a study of cemented Charnley and Stanmore femoral stems. J Bone Joint Surg [Br] 1995;77-B:705–714. Ornstein E, Franzén H, Johnsson R, et al. Hip revision using the Exeter stem, impacted morselized allograft bone and cement: a consecutive 5-year radiostereometric and radiographic study in 15 hips. Acta Orthop Scand 2004;75:533–543. Heekin RD, Engh CA, Vinh T. Morselized allograft in acetabular reconstruction. A postmortem retrieval analysis. Clin Orthop Relat Res 1995;(319):184–190.

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CHAPTER

28

Daniel J. Berry

Allograft Prosthetic Composite

INTRODUCTION METHODS INTUSSUSCEPTION TECHNIQUE RESULTS COMPLICATIONS

INTRODUCTION Allograft prosthetic composites have been used for several decades to reconstruct the severely deficient proximal femur in revision total hip arthroplasty.1–6 This reconstruction method is predicated on the concept that a prosthesis can be cemented to a large bone allograft and the allograft can be mechanically joined to the host femur to allow bone-to-bone healing between the host bone and the allograft. Allograft prosthetic composites provide an effective method of gaining limb length when reconstructing the markedly deficient proximal femur. The main competing technology in these cases is an all-metal tumor prosthesis that replaces the proximal femur. Allografts provide some benefits over tumor prostheses: allografts provide the potential for soft tissue attachment and the potential for healing of remaining proximal femoral bone—including the greater trochanter—to the allograft. When satisfactory trochanteric bone is present, the technique has the potential advantage of providing better abductor function, through trochanteric healing, than would be present after most tumor prosthesis reconstructions. Allograft prosthetic composites also may be more durable than cemented tumor prostheses. Allograft prosthetic composites, however, should not be understood to provide more bone stock “restoration” than tumor prostheses. Massive allografts heal to host bone but then function essentially as an inert structural element and do not restore a substantial amount of living bone.7 Allografts also are subject to resorption with time.

Indications Allograft prosthetic composites are indicated for reconstruction of selected patients with massive proximal

femoral bone deficiency. Allografts have advantages over tumor prostheses for younger patients—because allografts may provide a more durable reconstruction—and for patients with good abductors and a greater trochanter (which can be reattached to the allograft, thereby providing better abductor function than would be present with a tumor prosthesis). An allograft-prosthetic composite reconstruction is more difficult technically than reconstruction with a tumor prosthesis, because of the carpentry required to get a good fit between allograft and host bone. Allografts also require bone-to-bone healing to occur for a successful reconstruction, which is not the case for a tumor prosthesis. Therefore, for older, sicker patients, for whom more rapid rehabilitation is desirable, or for whom the medical risks of a more involved reconstruction are prohibitive, a tumor prosthesis may be preferred over an allograft prosthetic composite. For patients with modest proximal bone loss, which can be handled successfully with a conventional femoral reconstruction using an uncemented implant (with or without calcar buildup), a cemented implant with calcar buildup, or impaction grafting, an allograft prosthetic composite typically is not necessary. The indications for allograft prosthetic composites have diminished with time as more versatile uncemented implants have become available, as impaction grafting has become more sophisticated, and as tumor prostheses have improved. Nevertheless, allograft prosthetic composites play an important role in selected reconstructions of patients with severe proximal femoral bone deficiency (Figs. 28-1 and 28-2) and in very selected patients with Vancouver type B3 periprosthetic femur fractures. Allograft prosthetic composites may be used successfully in two-stage reconstructions of previously infected hips although judgment about risk of reinfection is required. Many different methods of joining an allograft to the proximal femur have been described. Each has its own advantages and disadvantages: some require more carpentry than others; some provide more immediate stability between allograft and host bone than others; and some are best suited to circumstances in which the allograft and host bone diameter are well matched, while others are best for cases of markedly discrepant allograft–host bone diameters.

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FIGURE 28-1. A: Radiograph of patient with markedly deficient proximal femur and failed femoral component. B,C: Radiograph after reconstruction with proximal femoral allograft.

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FIGURE 28-2. A: Radiograph of patient with markedly deficient proximal femur and failed femoral component. B,C: Radiographs after reconstruction with proximal femoral allograft.

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METHODS End-to-End Allograft to Host Bone Junction Several different methods of end-to-end allograft to host bone junction joinery have been described including a simple tranverse butt joint, a step-cut joint (Fig. 28-3), and an oblique joint.8–12 Most surgeons now prefer a step-cut because it provides the most rotational stability and also provides a greater surface area for bone healing (Figs. 28-4 and 28-5). The drawback of this method of reconstruction is the need for complex carpentry to gain a perfect fit of the allograft to host bone.

Technique Careful preoperative planning is essential for a successful allograft prosthetic composite reconstruction. Preoperative radiographs (with markers to calibrate magnification) of the whole host femur are obtained to assess femoral bone loss, femoral geometry, and femoral size. Radiographs of potential bone allografts also are obtained. In most cases, a proximal femoral allograft is appropriate; however, occasionally, a whole femoral allograft is necessary. A donor tibial allograft may be used instead of a femoral allograft in selected cases. The outside diameter of the allograft should be similar to the outside diameter of the host bone. Femoral allografts often come from younger donors with smaller diameter

FIGURE 28-3. A: Transverse butt joint between allograft and host bone. B: Step-cut joint between allograft and host bone. C: Oblique joint between allograft and host bone.

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femurs; thus, careful scrutiny of the diameter of potential allografts is necessary. It is important to choose an allograft of sufficient diameter to allow placement (after preparation) of a satisfactorily sized implant to provide stability across the allograft-host junction site. The hip may be exposed through an anterolateral approach or a trochanteric slide. Alternatively, if the proximal bone and trochanter are absent, the abductors and vastus lateralis may be split in line with their fibers in the midcoronal plane to provide a direct lateral approach to the hip. A posterior approach also may be used, but it disrupts the posterior soft tissue sleeve and may increase the already high risk of dislocation. The failed prosthesis is removed, and all cement and membrane are removed from the femoral canal. The distal femoral canal is prepared according to the planned distal diameter of the prosthesis. If the prosthesis will be press-fitted into the host bone, then the femur is reamed to the appropriate diameter. Based on the type of planned reconstruction, the proximal femoral allograft is provisionally prepared. If the implant will be cemented into the allograft—as is almost always the case— then the proximal femoral allograft is prepared with broaches and, if desired, reamers. The host bone then is contoured to the shape planned for the junction between the allograft and the host bone, which mostly commonly will be a step-cut. The portion of bone removed to form the step-cut and the length of the step-cut removed depends on the geometry of the bone defect. The step-cut may be oriented with the long host bone side medially or laterally depending on the bone defects present. Next the allograft is provisionally marked for the step-cut (or for the proposed geometry of the graft host bone joint). It is important to mark the allograft carefully if a step-cut is being used, to demonstrate which side of the stepcut will be retained and which side will be removed. Also, the allograft should be marked to provide for greater than the expected required length and circumference of the allograft; more always can be trimmed later after provisional trialing. Once the provisional cut has been made, a trial prosthesis is placed inside the allograft and host femur, and hip reduction is attempted. The length of the allograft is adjusted sequentially to provide the proper length/tension relationship. The allograft is further trimmed to optimize apposition of the allograft– host bone junction, a process that typically requires several iterations. The real prosthesis is cemented into the allograft in appropriate anteversion based on the position of the stepcut. The optimal anteversion should be marked carefully on the allograft before the implant is cemented in place. If a fully porous-coated or similar prosthesis will be press-fit into the host femur, a plastic “Steri-Drape” may be wrapped around the distal prosthesis before it is inserted through the cement to the allograft. The nonsticky portion of the Steri-Drape is wrapped around the prosthesis followed by the sticky portion of the Steri-Drape, providing a sheath for the prosthesis and preventing cement from bonding to the distal stem during the cementation process. Any extra cement is carefully removed as the cement cures.

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FIGURE 28-4. A: Radiograph of patient with deficient proximal bone due to osteolysis. B: Radiographs after reconstruction with a proximal femoral allograft using step-cut joint between allograft and host bone.

FIGURE 28-5. Intraoperative picture of allograft prosthetic composite with step-cut graft–host bone junction. Note the excellent bone apposition.

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After the cement has cured, the allograft prosthetic composite is prepared for insertion into the host bone. If a Steri-Drape has been used to protect the distal prosthesis, it is removed at this time. A prophylactic cerclage cable or wire typically is placed around the femur just distal to the allograft prosthetic composite junction if an implant will be press-fitted into the host femur. The distal aspect of the implant then is inserted into the host bone and impacted until the allograft– host bone junction is well-opposed. If the implant is being cemented into the host bone, a cement restrictor is placed in the femur at an appropriate depth. In this case, cement is inserted into the host femur with a cement gun and pressurized, and then the implant is inserted into the cement. It is important to remove all cement possible from the allograft– host bone junction. After the prosthesis has been inserted and is stable, the allograft–host bone junction is further secured with cables (usually two) (Fig. 28-5). If autogenous host bone is available, it is packed along the allograft–host bone junction. Strut allografts also can be used to enhance the stability of this junction, but primary stability without strut grafts is preferable, because strut graft healing to allograft is unpredictable. If proximal host bone femur fragments are present and have been kept vascular, they may be wrapped around the allograft–host bone junction. If host greater trochanter is present, the medial surface of the host trochanteric fragment is freshened. The outer cortex of the allograft greater trochanter is removed with a saw,

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and the trochanter is fixed with wires or suture. Cables are less desirable in these cases because the healing rate at this junction is only about 75%, and if healing does not occur, cable fretting debris may be problematic. Abductors usually are not sewn to the allograft as this may induce revascularization and resorption of the allograft. If possible, the abductor–vastus lateralis sleeve is reapproximated to itself from anterior to posterior over the allograft. Deep drains are placed and the fascia is closed carefully to protect the allograft. Postoperatively touch weight bearing is recommended until radiographic evidence of allograft–host bone junction healing is visible radiographically, a process that typically takes 3 to 5 months, but can take longer. If union is markedly delayed, autogenous bone grafting may be considered. In most cases a prophylactic hip guide brace for 2 to 3 months postoperatively is used to reduce the risk of early dislocation.

INTUSSUSCEPTION TECHNIQUE The allograft intussusception technique may be used in special circumstances when the proximal host femur is absent and the remaining femoral canal is wide and patulous (Fig. 28-6). Alternative treatment methods in these circumstances

include cementing a tumor prosthesis into the femur—which may have a high loosening rate if the femur is multiply revised and the canal is sclerotic—or reconstruction with a very-large– diameter uncemented extensively porous-coated or fluted tapered stem. This allograft intussusception technique is predicated on the idea that a femoral allograft can be milled until it fits inside a large-diameter host femur. The allograft then is impacted into the femur to achieve a pressfit similar to that obtained by an uncemented implant. The large surface area of the allograft against host bone facilitates healing. The new femoral canal provided by the allograft provides a good interface for cemented prosthesis fixation. This technique is most valuable in patients with severe segmental proximal femoral bone loss in association with a markedly widened femoral canal.

Technique Preoperatively, the surgeon chooses an optimal femoral allograft based on preoperative templating (using radiographs of the allograft) compared to radiographs of the failed hip replacement. Differing magnifications of the two films are taken into account. The surgeon must decide whether the allograft will be inserted with the proximal end of the allograft femur nearest to the hip joint or the distal end of the allograft femur nearest to the hip joint (i.e., with the allograft “right side up” or “upside down”). The narrowest diameter of the allograft femur is

FIGURE 28-6. A: Radiograph of patient’s hip with markedly deficient proximal femoral bone, wide femoral canal, and loose femoral component. B: Radiographs after reconstruction with intussusception allograft prosthetic composite.

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proximal to the midpoint of the femur; hence, a longer allograft can be obtained (when needed) by inverting the allograft. The hip joint is exposed by splitting the iliotibial band and then the gluteus medius in the coronal plane in the direction of their respective fibers. If a greater trochanteric fragment remains, it may be reflected anteriorly as a trochanteric slide or split in half longitudinally in the coronal plane. Exposure of the remaining femur is gained by splitting the vastus lateralis longitudinally. The failed femoral component and remaining cement within the femoral canal are removed. The canal is reamed with either flexible reamers or straight-tapered reamers until the host bone has been freshened. Sometimes the canal is too large to accommodate any reamers, in which case the canal is freshened with back-biting instruments from the cement removal set. The femoral allograft (usually a whole femur) is brought onto the field. The surgeon should strive to engage a substantial length of the allograft inside the host femur. The femoral allograft is osteotomized at an appropriate level, usually near the narrowest diameter of the graft. Next the external dimensions of the allograft are shaped with a high-speed cutting burr. A barrel-shaped burr works particularly well for this purpose, and the femur is shaped in a manner similar to peeling a carrot, sequentially trimming the allograft to fit the internal shape and dimensions of the femur. The allograft femur is milled to a gently tapered shape, and care is taken not to overprepare the

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allograft, because a firm pressfit into the host femur is necessary for success. The allograft is shaped and tested in the host bone in an iterative manner until the graft is properly sized. An excellent friction fit between the host bone and the allograft typically is achieved, provided sizing is correct. Next the femoral allograft is prepared provisionally for a long-stem cemented femoral component of the surgeon’s choice using reamers and broaches. A prophylactic cable is placed around the host femur and tightened provisionally. The allograft is oriented appropriately rotationally, and then it is gently and gradually impacted into the femur. To match the bow of the femur, often it is necessary to start impacting the graft in extra “anteversion,” and to derotate the graft gradually into proper anteversion as it is impacted deeper into the femur. As the graft is impacted, the prophylactic cable is tightened. An excellent press-fit of the allograft must be achieved, and the allograft must be both axially and rotationally stable at the completion of this process (Fig. 28-7). An important aspect of sizing the allograft is judging where the allograft will seat in the femur to provide appropriate length restoration of the limb. Impacting the allograft into the femur before cementing the implant into the allograft allows the surgeon to adjust soft tissue tension and leg length by modifying the proximal allograft (by trimming) or prosthesis length (by using a calcar buildup) after an optimal pressfit is obtained and the final allograft seating level is determined. Once the allograft is fully seated in the femur, a trial cemented

FIGURE 28-7. A: Radiograph of patient’s hip with markedly deficient proximal femoral bone, wide femoral canal, and loose femoral component. B: Radiographs after reconstruction with allograft prosthetic composite.

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Fixed hip femoral component

Femoral greater trochanter Acetabular component

FIGURE 28-8.

Pouch anterior superior to cup being elevated to accomodate the femoral head

Diagram of the intussusception allograft technique.

implant is placed in the allograft, and the final allograft neck osteotomy is performed at the optimal level. The author prefers to use a femoral component length that protects most of the allograft but that does not extend into the host femur beyond the allograft (unless necessary for stability of the construct). A cement restrictor is placed in the femoral canal. Using standard techniques, cement is introduced into the allograft with a cement gun and pressurized, and a cemented stem is inserted in proper anteversion (Fig. 28-8). If desired, remaining trochanteric remnants can be reapproximated to the allograft. Other remaining large host bone fragments with muscular attachments are reapproximated to the allograft with cerclage. Available host or allograft cancellous bone is packed around the allograft–host bone junction site to promote healing. Closure is performed in the standard manner, making an effort to close in layers to protect the allograft. Postoperatively, the patient usually receives a hip guide brace to reduce early dislocation risk. Weight bearing is limited to touch weight bearing for approximately 12 weeks, to give the graft time to heal to host bone. Subsequently, the patient may commence partial weight bearing and may progress weight bearing gradually over the following 2 months, so that by 4 to 5 months the patient is allowed full weight bearing. Healing of the allograft to host bone typically can be identified radiographically by 3 to 6 months after operation.

RESULTS Short- and midterm results of allograft prosthetic composite reconstruction of failed total hip arthroplasty with marked bone loss have been reported by a number of authors.13–15 These reports consistently document this is an efficacious

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technique to reconstruct massive proximal femoral bone loss. As expected, clinical results and hip scores typically are less good than those reported for simpler revisions because these patients often have had several revision arthroplasties before and also have deficient abductors or abductor attachments. Complication rates (see below) also tend to be higher due to the complex nature of the procedures. Longer term results of this reconstruction method have been reported by several authors in large numbers of patients. Blackley et al.16 reported the Toronto experience of 63 revisions with allograft prosthetic composites at 9 to 15 years (mean 11 years) after operation. Five hips failed due to infection, and three due to aseptic loosening. Two hips required reoperation for hip instability and three for problems with allograft– host bone junction site healing. The mean Harris Hip Score increased from 30 points preoperatively to 71 points postoperatively. Defining success as a Harris Hip Score increase of at least 20 points, a stable implant, and no additional surgery related to the allograft, the authors reported success in 78% of hips reconstructed in this manner. Haddad et al.17 reported the Vancouver experience with 55 proximal femoral allograft prosthetic composites followed a mean of 8.8 years (range, 3 to 12.5 years). They found six failures directly related to the allograft prosthetic composite: three graft-host nonunions, two infections, and one allograft fracture. The mean Harris Hip Score increased from 39 to 79 points. Allograft resorption was seen radiographically in seven patients, but had not led to clinical failure in any case. Finally, Wang and Wang18 reported a more cautionary experience in 15 patients followed a mean of 7.6 years after allograft prosthetic composite reconstruction for a total hip arthroplasty revision: ten patients (67%) had an intact construct at last follow-up. Allograft prosthetic composites have been reported to provide satisfactory results when used for specific indications. Alexeeff et al.19 reported good results in 11 patients revised with a twostage procedure for infection. No patients failed due to recurrent infection. Other authors have reported success in using allograft prosthetic composites in the reconstruction of comminuted periprosthetic femur fractures around total hip arthroplasty.

COMPLICATIONS Allograft prosthetic composites are at elevated risk for several specific complications.20 Hip dislocation is more common with allograft prosthetic composites than routine hip reconstructions because abductor attachments often are deficient. Reported dislocation rates range from 11% to 16% in larger series (Table 28.1). When severe abductor deficiency is present, a constrained liner or nonconstrained tripolar construct may be used at the time of allograft reconstruction. At a minimum, a large-diameter femoral head should be used—when possible—to enhance stability. Allograft prosthetic composite patients are at increased risk for infection because of the involved nature of the reconstruction, long operating time, and the use of avascular bone. The infection rate is reported from 4% to 20% in different series (Table 28.1). Consequently,

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CHAPTER 28 | ALLOGRAFT PROSTHETIC COMPOSITE

TABLE 28.1

Complications of Allograft Prosthetic Composite Reconstruction

Authors al.16

329

Blackley et Chandler et al.21 Graham et al.22 Haddad et al.17 Head et al.4 Wang and Wang18

Year

Number

Follow-up

Nonunion of Allograft–Host Bone Junction

Infection

Dislocation

2001 1994 2004 2000 1999 2004

63 30 25 55 98 15

11 y 22 mo 53 mo 8.8 y N/A 7.6 y

3/63 2/30 5/25 5/55 8% 2/15

5/63 1/30 1/25 2/55 3% 3/15

4/63 5/30 N/A 6/55 10% N/A

N/A, not available.

antibiotic impregnated cement is reasonable to use for the cemented portion of these reconstructions, and perioperative intravenous perioperative prophylactic antibiotics are essential in these patients, as in other revision patients. Nonunion of the allograft–host bone junction has been reported in 6% to 20% of patients (Table 28.1). The risk of nonunion probably is in part technique dependent, which emphasizes the importance of gaining both a strong, mechanically stable construct and excellent graft–host bone contact. If the greater trochanter is attached to the allograft, the rate of healing has been reported to be modest (16 of 25 in Graham’s series22 and 33 of 55 in the Vancouver series17). Even

if radiographic union does not occur, fibrous union with fair abductor function may result. Allograft fracture may occur due to fatigue failure of the allograft. The key to preventing allograft fracture is protection of the entire allograft with a long-stemmed implant that extends well into the host bone, when possible (Fig. 28-9). Allograft resorption occurs in a modest number of patients. The phenomenon is incompletely understood and probably is partly related to immunologic factors. Direct attachment of soft tissues to the bony allograft and excessive holes in the allograft may promote this problem and when possible should be avoided.

FIGURE 28-9. A: Radiograph after hip reconstruction with allograft prosthetic composite. Note that the allograft is not entirely protected by an intramedullary stem and a fixation plate ends just distal to the femoral component, creating a stress riser. B: The allograft fractured in the highstress area 3 years postoperatively, requiring revision total hip arthroplasty.

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REFERENCES 1. Gross AE, Blackley HR, Wong P, et al. The role of allografts in revision arthroplasty of the hip. Instr Course Lect 2002;51:103–113. 2. Gross AE, Hutchison CR. Proximal femoral allografts for reconstruction of bone stock in revision arthroplasty of the hip. Orthop Clin North Am 1998;29:313–317. 3. Haddad FS. Circumferential allograft replacement of the proximal femur: a critical analysis. Clin Orthop Relat Res 2000;371:98–107. 4. Head W, Emerson RJ, Malinin T. Structural bone grafting for femoral reconstruction. Clin Orthop Relat Res 1999;369:223–229. 5. Head W, Malinin T, Berklacich F. Freeze-dried proximal femur allografts in revision total hip arthroplasty: a preliminary report. Clin Orthop Relat Res 1987;215:109–121. 6. Head WC, Hillyard JM, Emerson RJ, et al. Proximal femoral allografts in revision total hip arthroplasty. Semin Arthroplasty 1993;4:92–98. 7. Hamadouche M, Blanchat C, Meunier A, et al. Histological findings in a proximal femoral structural allograft ten years following revision total hip arthroplasty: a case report. J Bone Joint Surg Am 2002;84A:269–273. 8. Hakala BE, Moskal JT. Proximal femoral allografting in revision total hip arthroplasty: stabilization of the host-graft junction with tension band fixation. J South Orthop Assoc 2002;11:66–69. 9. Hamadouche M, Oakes DA, Berry DJ. Bone graft for total joint arthroplasty. In: Lieberman JR, Friedlaender GE, eds. Bone Regeneration and Repair: Biology and Clinical Applications. Totowa, NJ: Humana Press Inc; 2005:263–289. 10. Head W, Berklacich F, Malinin T, et al. Proximal femoral allografts in revision total hip arthroplasty. Clin Orthop Relat Res 1987;225:22–36. 11. McGovern BM, Davis AM, Gross AE, et al. Evaluation of the allograftprosthesis composite technique for proximal femoral reconstruction after resection of a primary bone tumor. Can J Surg 1999;42:37–45.

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12. Rodrigo JJ, Martin RB, Reynolds HB, et al. Interlocking femoral components for revision arthroplasty with allografts. J Arthroplasty 1990;5(Suppl):S35–41. 13. Allan DG, Lavoie GJ, McDonald S, et al. Proximal femoral allografts in revision hip arthroplasty. J Bone Joint Surg Br 1991;73B:235–240. 14. Barrack RL, Wolfe NW, Michas P, et al. Distal femoral allograft for massive proximal femoral deficiency. Acta Orthop Scand 2000;71:90–94. 15. Gross AE, Hutchison C, Alexeeff M, et al. Proximal femoral allografts for reconstruction of bone stock in revision arthroplasty of the hip. Clin Orthop Relat Res 1995;319:151–158. 16. Blackley HR, Davis AM, Hutchison CR, et al. Proximal femoral allografts for reconstruction of bone stock in revision arthroplasty of the hip: a nine to fifteen-year follow-up. J Bone Joint Surg Am 2001;83A:346–354. 17. Haddad FS, Garbuz DS, Masri BA, et al. Structural proximal femoral allografts for failed total hip replacements: a minimum review of five years. J Bone Joint Surg Br 2000;82B:830–836. 18. Wang JW, Wang CJ. Proximal femoral allografts for bone deficiencies in revision hip arthroplasty: a medium-term follow-up study. J Arthroplasty 2004;19:845–852. 19. Alexeeff M, Mahomed N, Morsi E, et al. Structural allograft in twostage revisions for failed septic hip arthroplasty. J Bone Joint Surg Br 1996;78B:213–216. 20. Martin W, Sutherland C. Complications of proximal femoral allografts in revision total hip arthroplasty. Clin Orthop Relat Res 1993;295: 161–167. 21. Chandler H, Clark J, Murphy S, et al. Reconstruction of major segmental less of the proximal femur in revision total hip arthroplasty. Clin Orthop Relat Res 1994;298:67–74. 22. Graham NM, Stockley I. The use of structural proximal femoral allografts in complex revision hip arthroplasty. J Bone Joint Surg Br 2004;86B: 337–343.

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CHAPTER

29

David J. Jacofsky

Proximal Femoral Replacement with Megaprostheses

INTRODUCTION HISTORY INDICATIONS SURGICAL TECHNIQUE POSTOPERATIVE CARE FUNCTIONAL OUTCOME AND RESULTS CONCLUSION

impaired due to adjuvant chemotherapy and/or irradiation, the use of these megaprostheses in nonneoplastic conditions and their indications continue to evolve. However, for the patient with the multiply revised hip, periprosthetic fracture in the face of marked osteolysis, or rarely even in severe cases of failed internal fixation for proximal femoral fractures, the situation is often analogous to the patient who has had complete resection of the proximal femur for neoplasia. Consequently, many of the same principles can be applied.

HISTORY INTRODUCTION With an increasing number of prosthetic hip replacements being performed in younger and more active patients, and with increasing life expectancies, there has been a steady increase in the number of revision hip arthroplasties being performed. As such, worsening femoral bone loss seen with progressive revisions has created a particularly complex and challenging problem. Osteolysis secondary to particulate debris, stress shielding, osteopenia due to aging, infection, and periprosthetic fracture can all contribute to the loss of bone stock around the femoral component of a total hip arthroplasty. Bone mass is further reduced surgically when multiple previous procedures have been performed.1–4 Various possible reconstructive options, as discussed in previous chapters in this book, are available to treat bone loss on the femoral side. Long cemented or press-fit femoral stems, definitive treatment with resection arthroplasty, impaction grafting, allograft prosthetic replacement, and modular replacement of the proximal femur with “tumor megaprosthesis” are all viable options in their appropriate settings. Allograft prosthetic composites or all metal megaprostheses may be required in patients whose severe bone deficiency or older age may preclude adequate fixation with more conventional implants. Although proximal femoral replacements have most commonly been used in neoplastic conditions when the majority of the proximal bone has been surgically resected, or when the biology of the remaining bone will be markedly

After the initial success of tumor prostheses in patients with neoplastic conditions, the indications for this type of reconstructive procedure begin to expand to include patients with massive proximal femoral bone loss secondary to other etiologies. The first modern reported case using a metallic (vitallium) implant to replace the proximal femur was in 1940 by Moore and Bohlman for treatment of a giant cell tumor.5 This prosthesis was actually secured via press fit, extracortically, on the femur. Chapchal’s book reported on the European pre-1970 experience with customized megaprostheses.6 Monticelli and Santori, in 1975, were the first to report on the concept of a modular segmental design, at the time made of stainless steel.7 In 1949, Scales at the Royal National Orthopaedic Hospital in Stanmore, England began to accrue over 300 patients undergoing salvage with a titanium segmental implant.8 This began to lay the groundwork for the development of modern designs for replacement of the proximal femur. Early North American designs for proximal femoral replacement were monoblock implants cast from a cobaltchrome alloy (Fig. 29-1). In the case of malignant conditions, additional bone was often removed such that the monolithic implant would then be equal to the length of resected portion of proximal femur. This often led to removal of significantly more bone than may have been required during the resection for the condition being treated. Additionally, as muscle is often removed with the resected specimen, and as the functional result of these patients had historically been of less concern

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Reamed Femur

Acetabulum

FIGURE 29-1.

Acetabulum and reamed femur.

than cure from malignancy, reattachment of the abductors initially had taken a secondary role. As the use of these megaprostheses has expanded into the realm of nonneoplastic conditions, refinements in design such as the introduction of modular prostheses that improve intraoperative flexibility and the introduction of provisions to allow for improved abductor soft tissue reattachment have ensued (Fig. 29-2).

INDICATIONS In general, all metal megaprostheses are best reserved for elderly or sedentary patients with massive quantitative or qualitative proximal bone loss. This may be due to failed total hip arthroplasty, previous periprosthetic sepsis, and recalcitrant and multiply failed nonunion of the proximal femur, or prior resection arthroplasty. In physiologically younger patients who have improved capacity to heal and in whom the restoration of bone stock for future revisions is of paramount importance, the allograft prosthetic composite is typically preferred. In either case, unless a total femoral replacement is planned, one absolute requirement is a distal length of bone that is adequate and suitable for fixation of the proximal femoral replacement. Elderly patients with multiple medical comorbidities and the inability to follow postoperative weight bearing restrictions constitute a relative indication to consider megaprosthesis reconstruction megaprosthesis reconstruction. Usually, the surgery is less technically demanding and requires shorter anesthesia time compared with more complex reconstructive procedures for massive bone loss.3,9,10

SURGICAL TECHNIQUE

FIGURE 29-2. As the use of these megaprostheses has expanded into the realm of nonneoplastic conditions, refinements in design such as the introduction of modular prostheses that improve intraoperative flexibility and the introduction of provisions to allow for improved abductor soft tissue reattachment have ensued.

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In most cases, the preferred surgical technique for the placement of a tumor prosthesis is the direct lateral approach (Hardinge). If the greater trochanteric bone is viable and substantial, a greater trochanteric slide can be used to mobilize the abductors and vastus lateralis anteriorly and expose the anterolateral aspect of the femur. If, however, massive lysis of the greater trochanter exists and it provides no biomechanical benefit, then it can be split longitudinally in line with the exposure. Meticulous soft tissue handling is important in maintaining the viability of the proximal musculature in order to optimize healing. Even in patients not suspected of being infected, intraoperative culture and frozen section are obtained in all surgical cases. As in all cases of revision total hip arthroplasty, thorough irrigation and

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CHAPTER 29 | PROXIMAL FEMORAL REPLACEMENT WITH MEGAPROSTHESES

debridement should be performed to minimize future potential third body wear by polyethylene and metal debris that may be present in and around the hip joint. Careful preoperative planning and intraoperative assessment is essential in determining the length of the femoral component to be used and the location of the transverse femoral osteotomy. Preoperative radiographs of the contralateral limb with markers are often helpful, but may be difficult to interpret in patients with prior reconstructive procedures on the contralateral side. My preferred method is to place a Steinmann pin in the iliac crest and measure to a fixed point on the femur prior to dislocation. This distance can then be recreated, plus or minus any increase or decrease in leg length that was desired based upon preoperative limb-length discrepancy. However, because instability is a substantial risk, particularly in light of abnormal abductor muscle attachments, soft tissue tension ultimately determines what length and offset is appropriate in most cases. In some cases, a constrained liner may be necessary when soft tissue tension to gain hip stability cannot be gained while maintaining an acceptable leg length. It is important to recognize that with the abductors detached from the construct, there is little check-rein to stretching of the sciatic nerve, and therefore, care must be taken to avoid over-lengthening. The transverse femoral osteotomy is then made in the host bone at the most proximal area of adequate circumferential quality bone as templated preoperatively and confirmed intraoperatively. Subperiosteal dissection and placement of a curved or malleable retractor is useful to protect the soft tissues and neurovascular structures prior to osteotomy with a saw. The surgeon should strive to maintain the maximum length of native femur possible because some studies have shown that outcome is related to the length of femur remaining postoperatively.9 Component removal should be carried out as described in previous chapters. The femur is prepared in standard fashion for the implant system being utilized. This typically involves reaming of the femoral canal to at least 2 mm greater than the selected stem size. If the acetabulum is not to be revised, trial components are then inserted and the stability of the hip can be examined. If acetabular bone loss and/or loosening is present and requires reconstruction, this should be performed as outlined in Chapters 9 to 18 of this text. If instability is a concern after trialing, a constrained liner may be used. During trial, the hip should generally be able to be flexed to 90 degrees and extended to 15 degrees. If this is difficult, or if the knee does not easily bend to 90 degrees, then the leg may be over-lengthened and this should be carefully examined. After adequate trial and confirmation of stability and femoral anteversion, the femoral component is cemented into place. Third generation cement technique and hypotensive anesthesia, if not contraindicated, should be performed. We often use antibiotic impregnated imprepriated cement in these complex reconstructions. A cement restrictor can be used if feasible, but often the stem tip lies in the capacious distal metaphyseal region of the femur, making the restrictor of little value. If an implant with a porous section or extramedullary bridges is used, ensuring that the porous-coated portion of the stem is in contact with the diaphyseal bone with no interpositioning of cement

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will improve results. This junction can be optimized by the use of a reamer that matches the flair at the proximal aspect of the stem prior to cementation. A Steri-Strip or a piece of wet gel foam wrapped around the porous surface of the body on the stem can help protect this interface. Once the cement begins to cure, this can be peeled away to minimize contamination of the porous surface adjacent to the host bone with extruded cement. Protecting the porous coating over the implant at the host–implant junction will allow for extracortical bone bridging at this site. This theoretically will decrease the load transfer to the bone-cement interface of the femoral component and may improve loosening rates. Finite element analysis has confirmed that this bony bridging can decrease the stresses at the bone-cement interface of the femoral component.11 This bridging bone may also protect the bone-cement interface from exposure to polyethylene debris by isolating it from the effective joint space. Many routinely bone graft this junction. After the cement has cured, the soft tissues and remaining proximal host bone can be closed around the implant. Perhaps the most technically demanding part of this procedure is the reattachment of the abductor musculature. Most modern prostheses have holes about the proximal aspect of the implant, which allow for multiple, heavy nonresorbable sutures or nonabsorbable dacron tape to be used for reattachment of the abductors (Fig. 29-3). Some implants have provision for the use of a “thumb tack” or spiked washer and screw that can be placed through the greater trochanteric bone stock and reattached into the implant proximally. In the revision setting, however, this bone, if present at all, is generally weak. In most cases, I use no. 5 nonabsorbable suture in a modified Gerber fashion in the posterior sleeve, pass the suture through a hole in the implant at the appropriate location, perform a modified Gerber suture on the anterior sleeve, and pass the suture through the adjacent hole in the implant, and then back through the posterior sleeve. It is then tagged and will ultimately be tied over a heavy and wide soft tissue bridge of tendon. Usually three sutures of this type are passed and then are all tightly tied. It is important to make sure that the abductors are tensioned and not functionally lengthened. One way to help ensure this is to pass the sutures through a hole in the Abductors Reattached

FIGURE 29-3.

Abductors reattached.

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implant that is slightly more distal than the location of the sutures in the soft tissue sleeves and to perform this repair with leg abducted. Once these sutures have been tied, the anterior and posterior sleeves should come together deep (medially) about the implant, and the lateral edges of these sleeves can then be closed in an interrupted fashion with 0 vicryl suture over the superolateral shoulder of the implant. The soft tissue sleeves below the vastus lateralis ridge can be closed with absorbable suture. This should be performed with the leg in an abducted position, pulling the vastus proximally and attaching it to the abductors anteriorly and laterally. If the soft tissues around the trochanter are markedly deficient, dissection of the gluteus maximus posteriorly to its origin on the sacrum can be useful to mobilize the muscle and allow it to cover the lateral implant, closing it to the musculature anteriorly. The implant should be completely covered with soft tissue if the closure is performed correctly. Drains typically are placed prior to closure, and the wound is then closed in a standard fashion.

POSTOPERATIVE CARE I continue intravenous prophylactic antibiotics for 12 to 24 hours after removal of the deep drains when megaprostheses are used in the revision setting. We attempt to remove drains as early as possible to prevent colonization of the surgical bed. In most revision cases, drain output 5 cm in length, especially with a deficient trochanter, precludes the use of most conventional stems, and more involved reconstructive solutions must be utilized. Typically, these include the megaprosthesis or an allograft prosthetic composite. The megaprosthesis is typically more suitable for the elderly and sedentary patient who will benefit from immediate weight bearing, a shorter surgical time, and obviation of the need for the biologic healing of an allograft-host interface. The clinical results in virtually all series of megaprostheses measure dramatic improvement from preoperative hip scores with respect to pain and functional ability. Since the first generation megaprosthesis, implant design modifications, improved surgical techniques, and improved cementation protocols have been implemented and likely will continue to improve clinical results. The use of modular segmental components as compared to the previous monolithic

FIGURE 29-4.

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variety allows for closer approximation of soft tissue tension, restoration of appropriate leg length, and ability to preserve the maximum amount of viable bone. In addition, the use of porous coating over the implant allows for extracortical bone bridging which will likely improve long-term durability. Furthermore, this increased stress transfer to the femur through this extracortical bone may decrease stress shielding and resorption at the proximal end of the remaining femur. The role of completing uncemented fixation of megaprosthesis is now being explored, and has the potential to provide more durable fixation. Dislocation remains problematic. More modern series are beginning to show decreased dislocation rates with the use of standard liners, and the use of constrained liners to minimize this complication has become more prevalent in lower demand patients. Restoration of the soft tissue tension about the hip and the use of a postoperative abduction orthoses help to reduce the frequency of this complication. I now use these braces in virtually all patients for 6 to 8 weeks and believe this practice can reduce the rates of dislocation, which in previous series ranged from 22% to 36%.9,16,19 Modern surgical techniques and the use of contemporary, segmental implants allow the arthroplasty surgeon to manage complex and difficult revision cases with acceptable results. As we further refine surgical technique and optimize implant design, these procedures will likely continue to show improving outcomes. The realization that the management of the soft tissues is of paramount importance also will lead to improved results (Fig. 29-4).

Failure of a PFR.

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REFERENCES 1. Berry DL, Chandler HP, Rielly DT. The use of bone allografts in two stage reconstruction of failed hip replacement due to infection. J Bone Joint Surg 1991;73A:1460–1468. 2. Callaghan JJ, Salvati EA, Pellicci PM, et al. Results of revision for mechanical failure after cemented total hip replacement, 1979–1982. J Bone Joint Surg 1985;67A:1074–1085. 3. Gross AE, Hutchinson CR. Proximal femoral allografts for reconstruction of bone stock in revision arthroplasty of the hip. Orthop Clin North Am 1998;29:313–317. 4. Rubash HE, Sinha RK, Shanbhag AS, et al. Pathogenesis of bone loss after total hip arthroplasty. Orthop Clin North Am 1998;29:173–186. 5. Moore AT, Bohlman HR. Metal hip joint: a case report. J Bone Joint Surg Am 1943;25:688. 6. Chapchal G, ed. Operative treatment of bone tumors. Stuttgart, Germany: George Thieme Verlag; 1970. 7. Monticelli G, Santor F. Indicazioni all impiego di protesi nel trattamento delle fratture patologiche da tumori maligni primitivi e metastatici dello scheletro. In: Relazione al LX Congresso S.I.O.T, Roma, 1975:20–23. 8. Scales JT. Massive bone and joint replacement involving the upper femur, acetabulum, and iliac bone. Hip 1975;3:245. 9. Malkani A, Settecerri J, Sim FH, et al. Long term results of proximal femoral replacement for non-neoplastic disorders. J Bone Joint Surg 1995;77B:351–356. 10. Chandler HP, Clark J, Murphy S, et al. Reconstruction of major segmental loss of the proximal femur in revision total hip arthroplasty. Clin Orthop 1994;298:67–74.

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11. Chao EYS, Sim FH. Composite fixation of salvage prostheses for the hip and knee. Clin Orthop 1992;276:91. 12. Anderson ME, Hyodo A, Zehr RJ, et al. Abductor reattachment with a custom proximal femoral replacement prosthesis. Orthopedics 2002;25: 722–726. 13. Enneking WF, Dunham W, Gebhardt MC, et al. A system for the functional evaluation of reconstructive procedures after surgical treatment of tumors in the musculoskeletal system. Clin Orthop 1993;286:241–246. 14. Ogilvie C, Wunder J, Ferguson P. Functional outcome of endoprosthetic proximal femoral replacement. Clin Orthop 2004;426:44–48. 15. Ward WG, Johnston KS, Dorey FJ, et al. Loosening of massive proximal femoral cemented endoprostheses: radiographic evidence of loosening mechanism. J Arthroplasty 1997;12:741–750. 16. Haentjens P, DeBoeck H, Opdecam P. Proximal femoral replacement prosthesis for salvage of failed hip arthroplasty: complications in 2–11 year follow-up study in 19 elderly patients. Acta Orthop Scand 1996;67:37–42. 17. Zehr RJ, Enneking WF, Scarborough MT. Allograft-prostheses composite versus megaprosthesis in proximal femoral reconstruction. Clin Orthop 1996;322:207–223. 18. Kawai A, Backus SI, Otis J, et al. Gait characteristics of patients after proximal femoral replacement for malignant bone tumour. J Bone Joint Surg 2000;82B:666–669. 19. Ross AC, Tuite JD, Kemp H, et al. Massive prosthetic replacement for non-neoplastic disorders. J Bone Joint Surg 1995;77B:351–356.

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SECTION

5 Revision/ Reoperation for Specific Diagnoses

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CHAPTER

30

Brian J. Keyes R. Michael Meneghini Arlen D. Hanssen

Surgical Management of the Infected Total Hip Arthroplasty

INTRODUCTION TREATMENT METHODS WITH COMPONENT RETENTION TREATMENT METHODS WITH COMPONENT REMOVAL SALVAGE SUMMARY

INTRODUCTION Periprosthetic joint infection (PJI) remains one of the major complications that can ensue following total joint arthroplasty, with an incidence of 1% to 2% at 2 years postoperatively for both total hip and knee arthroplasty1,2 and up to 7% after revision surgery.3 Deep PJI in total hip arthroplasty (THA) is a devastating complication, while the complexity and duration of treatment impart significant physical, emotional, and financial costs to both the patient and treating physicians.4,5 An accurate and expedient diagnosis in the face of subtle clinical signs is mandatory for the treating physician. Decisions regarding treatment are multifactorial and patient specific. Multiple treatment options have been described for the management of an infected THA, including long-term antibiotic suppression, surgical debridement with component retention, one-stage or two-stage exchange, excision arthroplasty, arthrodesis, and hip disarticulation. This chapter focuses on the surgical management of periprosthetic infection in THA, while the etiology and diagnosis of periprosthetic sepsis are covered in detail in Chapter 53.

TREATMENT METHODS WITH COMPONENT RETENTION Antibiotic Suppression with Component Retention The concept of component retention with antibiotic suppression has been investigated in numerous reports. Although

the indications are limited for chronic suppression and component retention for deep periprosthetic THA infections, there still may be a small subset of patients that may be appropriate for or desire this treatment modality. Antibiotic suppression and prosthesis retention can succeed in some patients and may be considered in elderly debilitated patients with an early infection caused by bacteria responsive to oral antibiotic therapy. Suppressive therapy may also be considered for an otherwise compliant patient who refuses removal of an infected prosthesis. The organism must be sensitive to oral antibiotics, and the patient must be tolerant of the antibiotics.6 Antibiotic treatment alone will not eliminate deep periprosthetic infection but can be used as suppressive treatment when the following criteria are met: (i) prosthesis removal is not feasible due to the patient’s medical condition or other reason, (ii) the microorganism has low virulence, (iii) the microorganism is susceptible to an oral antibiotic, (iv) the antibiotic can be tolerated without serious toxicity, and (v) the prosthesis is not loose.7 The presence of other joint arthroplasties or a cardiac valvular prosthesis is a relatively strong contraindication to chronic antibiotic suppression as a treatment choice. One of the largest series in the literature was that of Goulet et al.,6 where they examined the effectiveness of antibiotic suppression in 19 deep periprosthetic hip infections. Indications included patients’ refusal of removal or medical contraindications to surgery. Requirements included well-fixed components, highly sensitive organisms, and no systemic sepsis. The follow-up period averaged 4.1 years after treatment and nine hips showed no deterioration, while seven prostheses failed, five of which demonstrated progressive hip sepsis. The authors concluded that in a very select patient population and known low-virulence organisms, this treatment displayed some utility in their small series. Antibiotic suppression with component retention may also be considered for medically infirm patients or elderly with massive bone loss that would preclude adequate reconstruction options. However, it should be emphasized that this treatment option should be used with caution, and the indications are limited as antibiotic suppression can lead to development of bacterial resistance and component retention can further complicate future infection eradication efforts.

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Surgical Debridement with Component Retention Surgical irrigation and debridement with component retention and supplemental antibiotic therapy are often accompanied by exchange of the polyethylene insert and associated femoral head exchange. This treatment option initially appears attractive to the patient and surgeon alike for several reasons that include low morbidity compared to a two-stage resection arthroplasty requiring multiple procedures, the desire by the patient to retain the prosthesis in many cases, a potentially falsely optimistic attitude about the effectiveness of current antimicrobial agents, and the impression that a failed attempt causes little harm.8 Because of this initial attractiveness, surgical debridement and component retention are an established treatment in practice and have been studied and reported extensively. However, the reported success rates for prosthesis retention in the literature are highly variable due to a lack of consistency in the definition of what is considered acute infection, studies containing multiple surgeons, and studies with nonconsecutive series of patients. Furthermore, the literature is skewed as to component retention effectiveness when depth of infection is included as a diagnostic variable, as studies have suggested improved results with acute superficial infections in contrast to deep infections.9,10 Periprosthetic infections are classified as positive intraoperative culture, early postoperative, acute hematogenous, or late chronic infection according to their duration of involvement and proximity to the preceding joint arthroplasty11 (Table 30.1). While many authors define acute postoperative infections as occurring within 4 weeks from surgery, others have considered this time period to be as short as 2 weeks and as long as 3 months.9,12,13 To our knowledge, the report by Azzam et al.14 is the largest series in the literature that examined open irrigation and debridement for the management of PJI. One hundred four patients (44 males and 60 females) were identified with an average follow-up of 5.7 years. Treatment failure was defined as the need for resection arthroplasty or recurrent microbiologically proven infection. According to these criteria, irrigation and debridement were successful in only 46 patients (44%). Patients with staphylococcal infection, elevated American Society of Anesthesiologists score, and purulence around the prosthesis were more likely to fail.14 Another study examined the medical records of 18 patients with acute periprosthetic

TABLE 30.1

Classification of Deep Periprosthetic Infection on the Basis of Clinical Presentation

I. Positive intraoperative culture II. Early postoperative infection A. Superficial B. Deep III. Acute hematogenous IV. Late chronic

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infections occurring within 28 days after thirteen THAs and five TKAs.10 The mean time to reoperation was 19 days after arthroplasty. At the last follow-up, retention of the hip or knee prosthesis was successfully achieved in four of five patients with superficial (extrafascial) infections compared to eight of thirteen patients with deep prosthetic infections.10 Similarly, Crockarell et al.8 cited 42 hips managed with open debridement, retention of the prosthetic components, and antibiotic therapy. After a mean duration of follow-up of 6.3 years, only six patients (14%), four of nineteen with an early postoperative infection and two of four with an acute hematogenous infection, had been managed successfully. This study and others have revealed a time-dependent success rate in achieving infection eradication when debridement and component retention are employed. Brandt et al.15 found a cure rate of 56% following debridement within 2 days of symptom onset, compared with only 13% when carried out >2 days after the onset of symptoms. Yet another series examined the effectiveness of arthroscopic lavage and debridement in the management of eight (8) acute THA infections.16 Infection eradication was successful in all patients at an average of 6 years’ follow-up. The authors attributed their success to strict selection criteria. Patients were promptly diagnosed and treated, grew low-virulence organisms, and were compliant in taking long-term oral antibiotic therapy. The organism responsible for infection also has been shown to be predictive of treatment outcome. The window of opportunity for a successful debridement is even less when the offending organism is Staphylococcus aureus. Brandt et al.17 found prostheses debrided more than 2 days after onset of symptoms were associated with a higher probability of treatment failure than were those debrided within 2 days of onset. Ideally, treatment of the infected THA with surgical debridement and component retention has the greatest efficacy if confined to PJIs that are either acute or acute hematogenous, that are detected within 2 days of symptom onset, and whose offending organism is of low virulence. This treatment modality in the face of chronic infection is most likely doomed to failure in the majority of cases.

TREATMENT METHODS WITH COMPONENT REMOVAL One-Stage Exchange In Europe and limited parts of the United States, single-stage (direct-exchange) revision arthroplasty is a viable option to treat patients with an infection at the site of a THA. The reinfection rates after directexchange arthroplasty have been noted to be higher than those utilizing the two-stage treatment protocol.18 The single-stage or direct-exchange protocol has not been embraced by most American orthopaedic surgeons, largely due to the lack of randomized trials comparing the two treatment techniques. While the major disadvantage is potentially higher reinfection rates, purported advantages include decreased morbidity, decreased recumbency between procedures found with the two-stage

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approach, and a technically easier treatment strategy to that of two-stage protocols. The economic impact imparted by the two-stage approach has led to continued research of direct exchange, especially in countries that have national socialized medical systems. Reports exist that have displayed some encouraging results in eradication of PJI after THA with single-stage or directexchange arthroplasty. Callaghan et al.19 reported on 24 onestage revision surgeries for septic failure of a THA in 24 patients. Infection reoccurred around two hips (8.3%). They concluded that direct exchange was reasonable and cost-effective as long as the method and select criteria were upheld. Their method and criteria included (i) patients without draining sinuses, (ii) patients without immunocompromise, (iii) patients with adequate bone quality after meticulous debridement, (iv) the use of antibiotic-impregnated cement, and (v) the use of 3 to 6 months of postoperative oral antibiotic therapy. Similarly, Ure et al.20 performed 20 one-stage revision surgeries for THA PJI. Three patients had a draining sinus tract at the time of the procedure. The methodology included meticulous debridement, administration of appropriate antibiotic therapy, and the use of antibiotic-impregnated cement. At an average of 9.9 years postoperatively, no patient had recurrence of infection. Two patients had revision for aseptic loosening. The authors commented on their relatively small study cohort but stated that this treatment modality in carefully selected patients resulted in successful outcomes. Nagai et al.21 performed the largest series consisting of 162 cases with a mean follow-up of 12.3 years. In this series, eradication of infection occurred in 85.2% of the patients, with 12.3% requiring further revision for recurrent infection.21 One study comparing single-stage versus two-stage exchange favored the two-stage procedure. Elson22 had a 12.4% rate of failure with the single-stage method, compared to 3.5% with the two-stage procedure. The use of antibiotic cement for the reimplantation of components in direct-exchange arthroplasty has been proven in the literature to provide better infection eradication. Direct exchange using plain bone cement without antibiotics has been successful in 40 (60%) of 67 infected THAs, whereas success was achieved in 1,352 (83%) of 1,630 hips treated with the use of antibiotic-impregnated cement.3 Increased interest in condensing the operative treatment into a single procedure and one hospitalization will lead to continued investigation of this treatment option. Level I randomized, prospective comparative studies with large study group numbers are needed to further ascertain if this treatment method can replace the current gold standard of twostage revision surgical protocols. With the ever-increasing development of resistant microorganisms and infected THAs with significant bone loss, direct-exchange arthroplasty should be used with extreme caution.

Antibiotic Cement Spacers For two-stage protocols, in the interval between septic THA resection and the eventual reimplantation of another prosthesis, local antibiotic is delivered via static or articulating spacers composed of

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PMMA (polymethylmethacrylate) cement. The primary role of antibiotic-laden PMMA cement is the delivery of local antimicrobial agents and to decrease soft tissue contracture via the space-occupying and soft tissue tensioning spacer. Antibiotic elution is highly dependent on the bone cement porosity, and mixing high doses of powdered antibiotics creates considerable cement porosity, facilitating increased antibiotic elution for at least 4 weeks.23 Combining two antibiotics in bone cement will improve elution of both agents, and the two most commonly used antibiotics in clinical practice are vancomycin and tobramycin.3 The use of at least 3.6 g of tobramycin and 1 g of vancomycin per package of bone cement is recommended to obtain effective elution levels.24,25 The local levels of antibiotic elution typically far exceed the levels observed in the serum during parenteral antibiotic administration.23 Furthermore, it appears that the systemic levels of antibiotic achieved with cement spacers are well tolerated by patients. Springer et al.26 examined 36 knees with insertion of a high-dose antibiotic spacer for infected knee arthroplasties. All spacers placed contained an average of 3.4 batches of cement, with an average total dose of 10.5 g of vancomycin and 12.5 g of gentamicin. All patients were followed up postoperatively until reimplantation for evidence of renal failure. At the time of reimplantation, no patients showed any clinical evidence of acute renal insufficiency, failure, or other systemic side effects of the antibiotics. Antibiotic-laden cement can be used in the form of beads or spacers in the interval between the first and second stages. A study comparing the efficacy of beads to spacer prostheses revealed infection-free rates to be nearly equivalent. However, the use of a spacer prosthesis was associated with a higher hip score, a shorter hospital stay, decreased operative times, less blood loss, lower transfusion requirements, fewer dislocations, and better walking capacity in the interim period.27 Therefore, we recommend spacers, either articulating or static, over beads if possible for the reasons outlined above. Articulated spacers provide proper soft tissue, limb length, and patient comfort due to the simulated hip joint articulation that is maintained between stages (Fig. 30-1A). These have several advantages, including improved function, preservation of bone stock, prevention of soft tissue contracture, and as a source of local delivery of antibiotics.28 To our knowledge, the series with the longest follow-up is that of Biring et al.,29 with a 10- to 15-year follow-up of the PROSTALAC (prosthesis of antibiotic-laden acrylic cement) articulated hip spacer system. A total of 11 of the 99 patients had a further infection, of which seven responded to repeat surgery with no further sequelae. The long-term success rate was 89% and with additional surgery this rose to 96%.30

Two-stage Exchange Delayed reimplantation after resection and administration of intravenous antibiotics during the resection interval appears to offer better overall success rates than direct-exchange techniques and is the most commonly accepted approach in North America for treatment of the septic THA (Fig. 30-1A,B). The first stage involves removal of

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FIGURE 30-1. A: AP radiograph of a resection for hip arthroplasty PJI after insertion of a PROSTALAC articulating cement spacer. Note the fill of the superior acetabular defect with antibiotic cement and placement of the “snap-fit” polyethylene liner of the PROSTALAC system. B: Postoperative radiograph demonstrating successful reimplantation THA with well-fixed femoral and acetabular components and acetabular augmentation.

the infected components, meticulous debridement, and insertion of an antibiotic-containing cement spacer. As described previously, the antibiotic cement spacer allows therapeutic elution of the antibiotics to act locally at the surgical bed, while the host patient also receives parenteral antibiotics, typically for 6 weeks’ duration. The ideal duration of antibiotics between stages has not been established. Lieberman et al.31,28 had a recurrence rate of 9% (3/32 hips) with 6 weeks of interval parenteral antibiotics. In one series, the rate of reinfection was 22% among those reimplanted after 22 weeks, compared to 15% in those operated on within 4 weeks.32,28 Cementless reimplantation after objective evidence of infection eradication has been supported by several studies (Fig. 30-1B). The use of cement at the second stage allows local antibiotic delivery, but the intermediate- and long-term results of cemented component longevity in the revision hip arthroplasty setting have been suboptimal.33–38 While historically, there had been concern cementless reimplantation would lead to higher reinfection rates, this has not been demonstrated in the literature. Kraay et al.39 reported the

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results of 33 two-staged revision THAs done for deep infection using cementless femoral components. The overall infection rate of 7% using this approach was comparable to previous reports of two-staged revision THAs done with cemented components fixed with antibiotic-containing bone cement. In addition, cementless femoral component fixation seemed to be more reliable and durable in comparison to previous reports of revision THA with cemented stems.39 Another study involving 29 patients reported a 10.3% infection recurrence rate with implantation of cementless components at the second stage and an interval PROSTALAC spacer.40 These results compare favorably with the 5% to 15% reinfection rates reported for two-stage exchange with cemented components.19,31 The Mayo Clinic reported a series of 168 patients (169 hips) with infected arthroplasty, all of which had two-stage reimplantation for the treatment of an infected THA between 1988 and 1998.41 The purpose of the study was to evaluate the mid- and long-term results with respect not only to the risk of reinfection but also to the mechanical durability of two-stage reimplantation for the treatment of an infected

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THA using an uncemented acetabular component and a cemented or uncemented femoral component. In the second stage, the femoral component was fixed with antibiotic-loaded bone cement in 121 hips; the remaining femoral components and all acetabular components were uncemented. At a mean of 7 years’ follow-up, 12 hips (7.1%) were reoperated on for reinfection, and 13 hips (7.7%) were revised for aseptic loosening or osteolysis. Aseptic loosening occurred on one or both sides of the joint in 24 hips (14.2%). The 10-year survivals free of reinfection and mechanical failure were 87.5% and 75.2%, respectively. The authors concluded that the method of femoral component fixation, either with or without cement, did not correlate with risk of infection, loosening, or mechanical failure.41 The virulence of the offending microorganism is another factor that must be considered when employing any treatment option. A series from Vancouver retrospectively reviewed 50 patients who had a two-stage revision THA for methicillin-resistant S. aureus or methicillin-resistant Staphylococcus epidermidis infection.42 They reported a treatment failure rate of 21% and lower functional scores to comparative studies in the literature. These results are humbling given the increasing prevalence of methicillin-resistant infections encountered in the modern arthroplasty era.42 Management of bone loss in revision and second-stage reimplantation settings is a common concern and often is encountered. Surgical management of the bone loss may be addressed as in the aseptic revision THA setting, with metal or allograft augmentation. Metal augmentation offers the advantages of ease of implantation, minimization of potential disease transmission, and elimination of the risk of nonunion or resorption of allograft (Fig. 30-2A,B). If trochanteric bone loss or abductor muscle deficiency is encountered, the surgeon should consider the use of a constrained liner to prevent recurrent instability, particularly in elderly or low-demand patients (Fig. 30-2C). One study performed in primary THA where allograft was employed for the reconstruction reported a significant increase in infection rate when compared to revisions without allograft.43 This trend has not been found when allograft was used in two-stage revisions for infection. More recent studies examining the use of allograft at revision for infection have reported rates of recurrence of up to 7.5%, which are comparable to those without the use of allograft.44–47 Results of infection following two-stage reimplantation have resulted in poor outcomes. In 34 patients treated for an infected THA with removal of the prosthesis and implantation of another prosthesis, infection recurred an average of 2.2 years after reimplantation. The authors concluded that patients in whom the same single microorganism can be identified from the failed primary THA and from the failed first reimplantation may be reasonable candidates for another attempt at a two-stage reimplantation of a third prosthesis.30,48 These patients are very difficult to treat and are often left with salvage procedures as their final treatment options.

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SALVAGE Resection Arthroplasty Resection arthroplasty of the hip is a highly effective method of eradicating infection (Fig. 30-3). However, this procedure is usually limited to salvage situations or reserved for infirm patients who would not tolerate a more complicated reconstruction procedure or treatment regimen. Although resection arthroplasty often provides pain relief, most patients require use of ambulatory aids, have an antalgic gait, fatigue easily, experience hip instability, and have a large limb-length discrepancy.30,49 One technical consideration for the surgeon to keep in mind is that resection arthroplasty does not preclude reimplantation at a later date. A series of 33 cases of resection arthroplasty noted eradication of infection in 32, although there was a significant deterioration in functional outcome to an unsatisfactory level in each.50 Castellanos et al. reported on 78 patients who underwent Girdlestone arthroplasty with a mean follow-up of 5 years. Their series demonstrated infection eradication in 86% and good pain relief in 83%, yet the authors reported functional results that were unsatisfactory and consistent with other studies in the literature.51 Overall, functional deficits limit resection arthroplasty to a salvage procedure in patients who are not candidates for reimplantation or who have failed multiple attempts at reimplantation. Technique for Two-Stage Protocol Diagnosis of infection and identification of infecting organisms are established, usually by hip aspiration.

First Stage (Under the Direction of the Surgeon) Exposure choice is at the surgeon’s discretion. If the femoral component is well fixed, an extended greater trochanteric osteotomy may be used. Acetabular and femoral components are removed using standard techniques, preserving as much bone as possible. Infected soft tissues are carefully and thoroughly debrided and nonviable infected bone is removed. The wound is irrigated with pulsatile lavage usually using 9 to 12 L of solution. An antibiotic-impregnated cement spacer, either static or articulating, is inserted. A number of different configurations of static and articulating spacers have been used. Antibiotics are mixed with the cement. Broadspectrum antibiotics that are effective against the main or presumed infecting organism are chosen. A common combination of antibiotics at our institution for antibiotic-impregnated cement spacers is 4.8 g of an aminoglycoside and 4 g of vancomycin mixed with a 40-g pack of methylmethacrylate cement. The wound is closed over drains using monofilament absorbable sutures. If an extended greater trochanteric osteotomy was used, it is closed with monofilament wire, not braided cable.

Resection Interval The patient is mobilized and intravenous antibiotic treatment is instituted, usually for 6 weeks. The antibiotic treatment is carried out under the care of an infectious disease specialist in most cases.

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FIGURE 30-2. A: AP radiograph of an elderly patient after resection arthroplasty for metal hypersensitivity reaction and severe bone and soft tissue loss now with a recurrent infection and open wound after debridement and placement of antibiotic beads B: Radiograph after repeat debridement and insertion of articulating PROSTALAC cement spacer. C: Radiograph 1 year after reimplantation THA with a constrained acetabular liner and a cemented proximal femoral replacement to address the severe bone loss and abductor deficiency.

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The postoperative protocol is routine following revision hip arthroplasty, and weight-bearing status is determined by the specifics of the hip reconstruction. Antibiotics are typically given until the final culture results from the reimplantation surgery are available.

SUMMARY The overall scope of prevention, diagnosis, and treatment for the infected THA is complex and variable. Prevention of prosthetic joint infection relies upon augmentation of the host response, optimization of the wound environment, and reduction of bacterial contamination in the preoperative, intraoperative, and postoperative time period.15 Definitive diagnosis is often difficult and requires a heightened sense of suspicion. Treatment strategies should focus on establishing a rapid and accurate diagnosis, with clear and effective treatment algorithms to optimize long-term patient outcomes.

REFERENCES

FIGURE 30-3. AP radiograph of resection hip arthroplasty for a recurrent PJI infection in a noncompliant patient with extensive history of intravenous illicit drug abuse considered at excessively high risk for recurrent infection with reimplantation THA.

Erythrocyte sedimentation rate and C-reactive protein are checked at intervals. The implantation usually takes place about 12 weeks after the resection assuming serologic studies and the patient’s clinical course suggest infection resolution. The patient may be chosen for extended chemoprophylaxis following the resection to minimize thromboembolism risk during the period of reduced mobility.

Second Stage The wound usually is opened using the previous operative approach. If an extended greater trochanteric osteotomy was used to remove implants, it may be reopened (usually by judicious reosteotomy along previous osteotomy lines). Previously placed cement spacers are removed. Redebridement of the wound is performed and tissue is sent for pathologic examination. Assuming there is no evidence of ongoing infection clinically or based on the pathologic findings, new femoral and acetabular components are implanted using standard revision implants. Technical factors may include challenges in gaining good exposure and reconstituting leg length if a nonarticular spacer had been used. Careful trial reduction and assessment of hip stability are important because instability risk is elevated after two-stage revision procedures.

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1. Kurtz SM, Ong KL, Lau E, et al. Prosthetic joint infection risk after TKA in the Medicare population. Clin Orthop Relat Res 2010;468(1):52–56. 2. Ong KL, Kurtz SM, Lau E, et al. Prosthetic joint infection risk after total hip arthroplasty in the Medicare population. J Arthroplasty 2009;24 (6 suppl):105–109. 3. Hanssen AD, Rand JA. Evaluation and treatment of infection at the site of a total hip or knee arthroplasty. Instr Course Lect 1999;48:111–122. 4. Hebert CK, Williams RE, Levy RS, et al. Cost of treating an infected total knee replacement. Clin Orthop 1996(331):140–145. 5. Sculco TP. The economic impact of infected joint arthroplasty. Orthopedics 1995;18(9):871–873. 6. Goulet JA, Pellicci PM, Brause BD, et al.. Prolonged suppression of infection in total hip arthroplasty. J Arthroplasty 1988;3:109–116. 7. Tsukayama DT, Wicklund B, Gustilo RB. Suppressive antibiotic therapy in chronic prosthetic joint infections. Orthopedics 1991;14(8):841–844. 8. Crockarell JR, Hanssen AD, Osmon DR, et al. Treatment of infection with debridement and retention of the components following hip arthroplasty. J Bone Joint Surg Am 1998;80:1306–1313. 9. Van Kleunen JP, Knox D, Garino JP, et al. Irrigation and debridement and prosthesis retention for treating acute periprosthetic infections. Clin Orthop Relat Res 2010;468:2024–2028. 10. Van Kleunen JP, Knox D, Garino JP, et al. Irrigation and débridement and prosthesis retention for treating acute periprosthetic infections. Clin Orthop Relat Res 2010;468(8):2024–2028. 11. Tsukayama DT, Goldberg VM, Kyle R. Diagnosis and management of infection after total knee arthroplasty. J Bone Joint Surg Am 2003;85 (suppl 1):S75–S80. 12. Burger RR, Basch T, Hopson CN. Implant salvage in infected total knee arthroplasty. Clin Orthop Relat Res 1991;273:105–112. 13. Galat DD, McGovern SC, Larson DR, et al. Surgical treatment of early wound complications following primary total knee arthroplasty. J Bone Joint Surg Am 2009;91:48–54. 14. Azzam KA, Seeley M, Ghanem E, et al. Irrigation and debridement in the management of prosthetic joint infection: traditional indications revisited. J Arthroplasty 2010;25(7):1022–1027. 15. Brandt CM, Sistrunk WW, Duffy MC, et al. Staphylococcus aureus prosthetic joint infection treated with debridement and prosthesis retention. Clin Infect Dis 1997;24:914–919. 16. Hyman JL, Salvati EA, Laurencin CT, et al. The arthroscopic drainage, irrigation, and debridement of late, acute total hip arthroplasty infections: average 6-year follow-up. J Arthroplasty 1999;14:903–910.

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17. Brandt CM, Sistrunk WW, Duffy MC, et al. Staphylococcus aureus prosthetic joint infection treated with debridement and prosthesis retention. Clin Infect Dis 1997;24:914–919. 18. Wolf CF, Gu NY, Doctor JN, et al. Comparison of one and two-stage revision of total hip arthroplasty complicated by infection: a Markov expected-utility decision analysis. J Bone Joint Surg Am 2011;93:631–639. 19. Callaghan JJ, Katz RP, Johnston RC. One-stage revision surgery of the infected hip. A minimum 10-year follow-up study. Clin Orthop Relat Res 1999;369:139–143. 20. Ure KJ, Amstutz HC, Nasser S, et al. Direct-exchange arthroplasty for the treatment of infection after total hip replacement. An average ten-year follow-up. J Bone Joint Surg Am 1998;80:961–968. 21. Nagai HWM, Gambbir AK, Kay PR, et al. One stage revision total hip replacement for deep infection: 5-to 27- year follow-up study. Procs 70th Annual Meeting. American Academy of Orthopaedic Surgeons, 2003. 22. Elson RA. Exchange arthroplasty for infection: perspectives from the United Kingdom. Orthop Clin North Am 1993;24:761–767. 23. Hanssen AD, Spangehl MJ. Practical applications of antibiotic-loaded bone cement for treatment of infected joint replacements. Clin Orthop 2004(427):79–85. 24. Penner MJ, Masri BA, Duncan CP. Elution characteristics of vancomycin and tobramycin combined in acrylic bone-cement. J Arthroplasty. 1996;11(8):939–944. 25. Masri BA, Duncan CP, Beauchamp CP. Long-term elution of antibiotics from bone-cement: an in vivo study using the prosthesis of antibiotic-loaded acrylic cement (PROSTALAC) system. J Arthroplasty 1998;13(3):331–338. 26. Springer BD, Lee GC, Osmon D, et al. Systemic safety of high-dose antibiotic-loaded cement spacers after resection of an infected total knee arthroplasty. Clin Orthop Relat Res 2004;427:47–51. 27. Hsieh PH, Shih CH, Chang YH, et al. Two-stage revision hip arthroplasty for infection: comparison between the interim use of antibioticloaded cement beads and a spacer prosthesis. J Bone Joint Surg Am 2004; 86-A:1989–1997. 28. Toms AD, Davidson D, Masri BA, et al. The management of periprosthetic infection in total joint arthroplasty. J Bone Joint Surg Br 2006; 88-B:149–155. 29. Biring GS, Kostamo T, Garbuz DS, et al. Two-stage revision arthroplasty of the hip for infection using an interim articulated PROSTALAC hip spacer: a 10- to 15-year follow-up study. J Bone Joint Surg Br 2009;91(11):1431–1437. 30. Hanssen AD, Spangehl MJ. Treatment of the infected hip replacement. Clin Orthop Relat Res 2004;420:63–71. 31. Lieberman JR, Callaway GH, Salvati EA, et al. Treatment of the infected total hip arthroplasty with a two-stage reimplantation protocol. Clin Orthop 1994;301:205–212. 32. Colyer RA, Capello WN. Surgical treatment of the infected hip implant: two-stage reimplantation with a one-month interval. Clin Orthop 1994;298:75–79. 33. Iorio R, Eftekhar NS, Kobayashi S, et al. Cemented revision of failed total hip arthroplasty. Clin Orthop Relat Res 1995;316:121.

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34. Retpen JB, Varmarken JE, Rock ND, et al. Unsatisfactory results after repeated revision of hip arthroplasty. 61 cases followed for 5 (1–10) years. Acta Orthop Scand 1992;63:120. 35. Stromberg CN, Herberts P, Palmertz B. Cemented revision hip arthroplasty. A multicenter 5–9-year study of 204 first revisions for loosening. Acta Orthop Scand 1992;63:111. 36. Kavanagh BF, Ilstrup DM, Fitzgerald Jr RH. Revision total hip arthroplasty. J Bone Joint Surg Am 1985;67A:517. 37. Hunter GA, Welsh RP, Cameron HU, et al. The results of revision of total hip arthroplasty. J Bone Joint Surg Br 1979;61B:419. 38. Pellicci PM, Wilson PD Jr, Sledge CB, et al. Long- term results of revision total hip replacement. J Bone Joint Surg Am 1985;67A:513. 39. Kraay MJ, Goldberg VM, Fitzgerald SJ, et al. Cementless two-staged total hip arthroplasty for deep periprosthetic infection. Clin Orthop Relat Res 2005;441:243–249. 40. Masri BA, Panagiotopoulos KP, Greidanus NV, et al. Cementless twostage exchange arthroplasty for infection after total hip arthroplasty. et al. 2007;22:72–78. 41. Sanchez-Sotelo J, Berry DJ, Hanssen AD, et al. Midterm to long-term follow-up of staged reimplantation for infected hip arthroplasty. Clin Orthop Relat Res 2009;467(1):219–224. 42. Leung F, Richards CJ, Garbuz DS, et al. Two-stage total hip arthroplasty how often does it control methicillin-resistant infection? Clin Orthop Relat Res 2011;469:1009–1015. 43. Schutzer SF, Harris WH. Deep-wound infection after total hip replacement under contemporary aseptic conditions. J Bone Joint Surg Am 1988;70-A:724–727. 44. English H, Timperley AJ, Dunlop D, et al. Impaction grafting of the femur in two- stage revision for infected total hip replacement. J Bone Joint Surg Br 2002;84-B:700–705. 45. Alexeeff M, Mahomed N, Morsi E, et al. Structural allograft in two-stage revisions for failed septic hip arthroplasty. J Bone Joint Surg Br 1996;78B:213–216. 46. Berry DJ, Chandler HP, Reilly DT. The use of bone allografts in two-stage reconstruction after failure of hip replacements due to infection. J Bone Joint Surg 1991;73A:1460–1468. 47. Haddad FS, Muirhead-Allwood SK, Manktelow AR, et al. Two-stage un- cemented revision hip arthroplasty for infection. J Bone Joint Surg Br 2000;82:689–694. 48. Pagnano MW, Trousdale RT, Hanssen AD. Outcome after reinfection following reimplantation hip arthroplasty. Clin Orthop 1997;338: 192–204. 49. Grauer JD, Amstutz HC, O’Carroll PF, et al. Resection arthroplasty of the hip. J Bone Joint Surg 1989;71A:669–679. 50. Bourne RB, Hunter GA, Rorabeck CH, et al. A six-year follow-up of infected total hip replacements managed by Girdlestone’s arthroplasty. J Bone Joint Surg Br 1984;66-B:340–343. 51. Castellanos J, Flores X, Llusa M, et al. The Girdlestone pseudarthrosis in the treatment of infected hip replacements. Int Orthop 1998;22: 178–181.

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31

Matthew P. Abdel Daniel J. Berry

Revision for Hip Instability After Total Hip Arthroplasty

INTRODUCTION EPIDEMIOLOGY TREATMENT OPTIONS RESULTS TECHNIQUES POSTOPERATIVE MANAGEMENT

implants, or constrained implants) can improve the likelihood of success (Fig. 31-1). Each of these strategies is associated with its unique strengths and weaknesses, and the surgeon must constantly weigh the tradeoffs involved when choosing between different technologies and solutions. While choices and compromises are an essential feature of all revision surgery, nowhere is this more true than in revision for hip instability.

EPIDEMIOLOGY INTRODUCTION Larger diameter femoral heads and improved operative approaches and soft tissue repair/closure have somewhat reduced the incidence of recurrent dislocation after hip arthroplasty. Nevertheless, hip instability remains one of the most common reasons for reoperation after total hip arthroplasty (THA) and accounts for roughly a quarter of hip revisions in the United States in Medicare patients.25 These facts imply that the surgeon performing revision THA must know the differential diagnosis of hip instability, the available treatment options to solve hip instability, and the pros, cons, and indications for each. Historically, the rate of failure of reoperation for hip instability has been discouragingly high—between 20% and 40%—in most series. Fortunately, a better understanding of hip instability, and new technologies to solve the problem, make the success rate of the operation considerably greater at the present time. Surgeons have come to understand that hip instability can be caused by implant malposition, impingement, and inadequate soft tissue tension or integrity. Effective treatment targets the specific problem. However, in many cases, the problem is multifactorial, and several problems may need to be dealt with at once. Additionally, some patients may have cognitive problems, neuromuscular problems, or activity demands that put them at additional risk. For these reasons, surgeons have learned that trying to solve the specific identified problem and at the same time employing additional measures as needed (including large diameter femoral heads, tripolar constructs, dual mobility

Frequency of Hip Instability The prevalence of dislocation after THA varies widely, from 0.3% to 15%.1–7 In large series, the rate appears to be 2% to 3%.6,8–14 At the Mayo Clinic, Woo and Morrey15 noted 331 dislocations out of 10,500 primary and revision THAs, for a rate of 3.2%. However, the reported dislocation rate was 2.4% for primary THA and 4.8% for revision THA.15 After multiple procedures, the prevalence of dislocation after revision THA is much greater, with some series reporting rates from 10% to 28%.16,17 In an excellent review by Morrey, which combined the data in several large series, the dislocation rate was found to be 2% of 4,753 primary THAs and 6% of 1,290 revision THAs.3 Several presumed factors lead to an elevated risk for dislocation after revision surgery, including (i) poorer soft tissues, (ii) altered abductor muscle attachments, (iii) use of extensile surgical exposures at revision, and (iv) nonanatomic component positioning necessitated by bone loss. Regardless, the true prevalence of this problem is not known and varies due to heterogeneity of patient cohorts, different surgical techniques, and variable clinical follow-up.7,18,19 In addition, the prevalence of hip instability differs with time. Dislocations can be categorized as early (within 6 months), intermediate (6 months to 5 years), or late (>5 years).20 In most series, 60% to 70% of initial dislocations occur with the first 6 weeks after the index surgical procedure.7,8,11,14,21,22 The reduced risk over time is likely due to healing of soft tissues, improved muscle tone, and formation of a pseudocapsule around the joint.3,23 Berry et al.24 found that the cumulative rate of dislocation increased over time for Charnley 347

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FIGURE 31-1 A: Hip radiograph of an elderly patient with malpositioned acetabular component and recurrent instability. B: Hip radiographs after revision. Note the acetabular component was revised to an optimal position, and a constrained liner was added for additional security in this elderly patient with scoliosis and abnormal body mechanics.

THA, from 1% at 1 month to 1.9% at 1 year and then a constant additional rate of 1% every 5 years to a 7% rate at 25 years.

chronology of the dislocation (i.e., early, intermediate, or late), and (iii) patient-specific factors.

Hip Instability as Reason for Revision In a recent epidemiologic study by Bozic et al.,25 one of the most common causes of revision THA in the United States was instability, accounting for 22.5% of revisions. In another study by Jafari et al.,26 instability was the second most common indication for revision THA, accounting for 15% of the cases. Interestingly, instability was the second most common cause of failure for the revision procedures as well at 25.1%. The prevalence of recurrent dislocation necessitating operative treatment has been reported to range from 13% to 42%.2,7,27 Morrey noted that 22% of 142 hips that had recurrent dislocations required operative treatment.3

Closed Treatment The majority of dislocations that occur early (within 3 months of the procedure) and are the first or second dislocation(s) can be treated effectively with closed reduction.9 Certainly, there are exceptions, including those with failed implants, significant component malposition, and dislocations that cannot be reduced or closed. After reduction, the hip is immobilized for 6 to 12 weeks with either a hip abduction brace or hip spica cast. The brace limits hip abduction and flexion, whereas the cast provides even more constraint for those with very unstable hips. Patients treated nonoperatively have a >60% chance of avoiding future recurrence.8,12,15,21 At the Mayo Clinic, limiting flexion and internal rotation with a hip abduction brace for 6 weeks is the preferred means of treating first-time posterior dislocations.

TREATMENT OPTIONS The choice between surgical or nonsurgical treatment of hip dislocation is dependent on three factors: (i) whether the dislocation is recurrent (greater than two episodes), (ii) the

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Operative Treatment As previously noted, surgical treatment of hip instability is one of the most common causes of revision THA. Furthermore, the redislocation rate after

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reoperation for hip instability has been reported to be as high as 40%.6,9,28 As such, surgeons must understand the (i) direction of the dislocation (anterior, posterior, or directly lateral), (ii) etiology of the dislocation, and (iii) techniques and technologies that may aid in rectifying the problem. The etiologies contributing to instability can be placed in one or more of the following categories: component malposition, impingement, unsatisfactory soft tissue tension, and/or abductor deficiency/ trochanteric nonunion.

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Diagnoses COMPONENT MALPOSITION Component malposition is one of the most common causes of recurrent hip instability (Fig. 31-2). Furthermore, it is one of the factors often avoidable by the surgeon. Malposition can occur with either the acetabular or femoral component, although acetabular malposition is more common. Lewinnek et al.13 found that the safe zone for placement of the acetabular component was in

FIGURE 31-2. A,B: Hip radiographs of a 57-year-old woman with recurrent anterior dislocation after primary THA. The acetabular component position is excessively vertical and excessively anteverted. C,D: Hip radiographs after acetabular revision to optimize cup position.

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40 ± 10 degrees of abduction and 15 ± 10 degrees of anteversion.13 Excessive anteversion will predispose to anterior dislocations, whereas retroversion will predispose to posterior dislocations. An overly abducted socket (too vertical) may increase the risk of lateral dislocation when the leg is adduced. Fackler and Poss10 showed that 44% of 34 patients with dislocations had malposition of one or both components, compared with 6% in a control population with stable hips. Ali Khan et al.8 found that half of 142 patients with hip dislocations had unsatisfactory acetabular component anteversion or abduction. Daly and Morrey9 documented similar findings at Mayo. Currently, there is a paucity of literature surrounding femoral component position due to the fact that accurate measurements of femoral component anteversion are difficult to assess on plain radiographs. Furthermore, femoral component malpositioning is easier to avoid intraoperatively. However, most agree that excessive anteversion increases the risk of anterior dislocation, whereas inadequate anteversion results in increased posterior dislocation. Computed tomography may assist in determining the version, particularly if revision surgery is considered, given that removal of a well-fixed stem may result in significant bone loss. Regardless, Daly and Morrey9 reported that improper femoral component version was rarely an isolated cause of instability. However, in the series by Fackler and Poss10 and a study by Herrlin et al.,29 excessive and inadequate anteversion, respectively, were associated with hip instability. It is important to note that anteversion is additive. While excessive anteversion of either component alone may not always cause a problem, the combination of excessive anteversion in both components has a higher change of leading to dislocation.30 Most experts agree that combined acetabular and femoral anteversion should be approximately 45 degrees when a posterior approach is used and a little less when an anterior approach is utilized.6 IMPINGEMENT Impingement is the process by which bony structures, soft tissues structures, or the prosthesis itself can serve as a fulcrum, allowing the prosthetic head to be levered out of the socket.6 Based upon the position of the hip, various forms of impingement may occur. With the hip flexed and internally rotated, the greater trochanter or anterior proximal femur can impinge on the pelvis. Furthermore, any form of soft tissue can serve as a fulcrum in this position. In extension, adduction, and external rotation, impingement can occur between the femur and ischium, leading to anterior dislocations. Prosthetic impingement may occur secondary to implant malposition, poor head-toneck ratio, and elevated rims. Low head-to-neck ratios and elevated rims result in decreased range of motion prior to impingement. Amstutz et al.31 showed that femoral components with an increased head-to-neck ratio had greater range of motion prior to impingement, thus limiting dislocations. Moreover, Krushell et al.32 noted decreased impingement with a modular

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neck design in which the neck geometry was flattened. In essence, longer modular heads with a skirt result in early impingement since the femoral neck diameter is increased. Inadequate soft tissue tension is truly a spectrum, with the most severe example being abductor insufficiency/trochanteric nonunion (discussed next). While not proven, poor soft tissue tension almost certainly contributes to hip instability.33 There are five main causes of unsatisfactory soft tissue tension: capsulectomy, reduction of femoral offset, limb shortening, extensive soft tissue dissection, and trochanteric nonunion. Historically, the incised capsule was allowed to form a “pseudocapsule.” However, reconstruction of the posterior capsule and short external rotators after a posterior approach was shown to reduce dislocation from 4.1% to 0% at 1-year follow-up in 395 patients.34 Likewise, Goldstein et al and White et al reported reductions in dislocation after this capsulorrhaphy technique.35,36 As such, it appears that capsulectomy reduces soft tissue tension and/or restraint to motion and is thus a risk factor for dislocation. In regard to femoral offset, Fackler and Poss10 showed that patients who dislocate frequently have a notable loss of femoral offset (average of 5.2 mm) compared to patients with stable hips (average of 0.02 mm) (Fig. 31-3). On the other hand, the data surrounding limb lengths and stability are ambiguous. Fackler and Poss10 found no statistical correlation between postoperative limb lengths and the incidence of dislocation. Furthermore, Coventry33 found that the operated limb was shorter than the opposite limb in only 25% of patients with late dislocations. Woo and Morrey15 noted that patients with unstable hips had limb lengths that were 1.6 mm longer than the contralateral limb. UNSATISFACTORY SOFT TISSUE TENSION

Abductor insufficiency is one the most difficult causes of hip instability to solve. The abductors may be deficient or dysfunctional secondary to trauma, failure of abductor or greater trochanteric healing after previous operations, or superior gluteal nerve dysfunction.6 The adverse effects of trochanteric nonunion, especially if associated with proximal migration, have been observed by many investigators.15,37,38 Woo and Morrey reported a 17.6% dislocation rate when trochanteric nonunion occurred with 1-cm proximal trochanteric migration.15 However, the incidence of dislocation was drastically lower at 2.8% in THAs in which an osseous or a stable fibrous union of the greater trochanter was obtained. Nevertheless, the cumulative risk of dislocation is statistically significantly lower with transtrochanteric approaches suggesting that when trochanteric healing occurs, the good soft tissue restoration and opportunity to advance the trochanter can provide excellent hip stability.39

ABDUCTOR INSUFFICIENCY/TROCHANTERIC NONUNION

Treatment Algorithm IMPLANT MALPOSITION Implant malpositioning can be considered minor or major. Such a distinction is essential in determining treatment options. Minor adjustment to acetabular

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FIGURE 31-3. A,B: Hip radiograph of a patient with recurrent hip instability after primary THA. Note the acetabular component position is not optimal, and also note the femoral component does not provide nearly as much offset as the patient’s “native” hip. C,D: Hip radiographs after acetabular and femoral component revision. Implant position and femoral offset were optimized, and a larger diameter femoral head was added to further optimize hip stability.

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position can be accomplished with the use of elevated-rim liners for modular sockets or socket wall additions for nonmodular sockets (Fig. 31-4).40–44 The elevated-rim or facechanging liner can be placed posteriorly to produce more effective cup anteversion, anteriorly to decrease relative anteversion, and directly lateral to reduce the relative cup abduction. In a laboratory simulator, Krushell et al.45 were able to show that elevated rims improved stability when used to compensate for a malpositioned acetabular shell. Likewise, in the initial Charnley design, an acetabular component with an elevated posterior wall decreased the dislocation rate.2 The above advantages must be balanced with the increased risk of polyethylene wear and component loosening. Markedly malpositioned implants require component reorientation. The acetabular component is typically revised given that malposition of this component is more frequent, combined with the fact that measurement of the femoral component position on plain radiographs is more difficult.7 As

previously stated, the safe zone for the acetabular component is in 40 ± 10 degrees of abduction and 15 ± 10 degrees of anteversion.13 In addition, the surgeon must be aware that patients roll forward during a posterior approach with the patient in a lateral position, leading to an exaggerated sense of acetabular anteversion. This is enhanced during the posterior approach given the fact that the internal rotation of the femur rolls the pelvis forward. As such, bony acetabular landmarks including the ischium posteriorly, the bottom of the fovea inferiorly, the anterior wall, and the lateral acetabulum are essential guides to implant position intraoperatively. Furthermore, an intraoperative radiograph can be very valuable. Medialization of the hip center leads to an increased risk for bony impingement between the femur and pelvis and thus increased risk for instability. As such, medial bone deficiencies should be addressed with extra large cups, extra depth cups, eccentric socket liners, and/or medial bone grafts to avoid medialization and the resultant potential problems of bone-to-bone impingement.

FIGURE 31-4. A,B: Hip radiographs of a woman with recurrent anterior hip instability. C: Hip radiographs after femoral head and liner exchange. A larger diameter head was used to minimize impingement, and a face-changing acetabular liner was placed to reduce effective acetabular anteversion.

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If impingement is contributing to hip instability, then the impingement source must be relieved. Impingement between the greater trochanter and pelvis with hip flexion and internal rotation may be treated either by excising a portion of the anterior greater trochanter or by removing hypertrophic soft tissues in the region of the anterior capsule and reflected head of the rectus femoris.6 Likewise, impingement between the femur and ischium with the leg in extension, adduction, and external rotation can be treated by removing prominent bone of the ischium or removing hypertropic posterior inferior capsule or scar tissue. When prosthetic impingement is the offending source, it can be relieved by improving the implant position, optimizing the head-to-neck ratio, or removing an elevated acetabular rim liner.6 In revision surgery, medial bone loss may result in placing the cup in a medialized position, increasing the risk of femoral bone–acetabular bone impingement and instability. In this case, a lateralized liner or deep profile acetabular component can help reconstitute the hip center of rotation. The surgeon, however, should be aware that lateralized liners do increase the torque on the acetabular component during weight bearing. Furthermore, the surgeon must be aware that removal of impingement alone is the least successful treatment for instability.3 IMPINGEMENT

UNSATISFACTORY SOFT TISSUE TENSION Similar to implant malposition, unsatisfactory soft tissue tension can be considered minor or major. Minor inadequacies in soft tissue tension sometimes can be treated with modular head and liner exchanges.46 The main method is to use a longer modular femoral head. Sometimes it is also possible to increase the femoral head-to-neck ratio and/or use an elevated liner to subtly improve effective component position. Such a treatment can only be successful if the patient has reasonably well-positioned and well-fixed acetabular and femoral components.20 Furthermore, the acetabular component in place must be sufficiently large to allow an adequately thick polyethylene to be used with the larger femoral head.20 Major deficiencies in soft tissue tension often require complete revision or trochanteric advancement. Because sources of hip instability are additive, if a patient is suffering from inadequate soft tissue tension and component malpositioning, the components must be reoriented. In addition, trochanteric advancement or some other means of gaining soft tissue tension, such as adding a longer modular neck, may be required. Ekelund47 reported success with trochanteric advancement in 19 of 21 patients. In addition, Kaplan et al.48 reported success with this technique in 17 of 21 patients. The risk, of course, is that of trochanteric nonunion, which can worsen the instability. Occasionally, trochanteric advancement may not be possible when the trochanteric fragment is dysvascular, small, or markedly deficient. In such scenarios, an attempt can be made to advance the greater trochanter to healthy host bone by “pie crusting” tight scar and tendons of the abductor mechanism from the proximal lateral ileum and advancing it distally on the superior gluteal neurovascular pedicle.6 Finally, some

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severe cases of poor soft tissue tension may be solved only with advanced technologies such as constrained implants (Fig. 31-5). INSUFFICIENCY/TROCHANTERIC NONUNION When complete abductor insufficiency or trochanteric nonunion is present, more advanced surgical solutions are required. Oftentimes, a combination of techniques is utilized to achieve stability. At the current time, surgical options include larger heads/ bipolars, unconstrained tripolars/dual-mobility systems, and constrained liners (Fig. 31-6). Large femoral heads increase the head-to-neck ratio, thereby increasing the range of motion before impingement and increasing the jump distance required of the head to dislocate.49 Furthermore, they provide greater direct soft tissue restrain to head displacement. Larger femoral head diameters also come in longer neck lengths without the need for skirts, thereby further optimizing head-toneck ratio. The disadvantage is the necessity to simultaneously inset a thinner polyethylene liner. ABDUCTOR

Advanced Technologies Recent advances in highly cross-linked polyethylene, which have improved wear characteristics, are allowing surgeons to use head sizes of 36 mm or more in many revision hip reconstructions. This is important as Berry et al.50 showed that larger femoral head diameters were associated with a lower long-term cumulative risk of dislocation. In particular, femoral head diameter had the greatest effect when in association with the posterolateral approach. Furthermore, in a recent study by Lombardi et al, large heads using alternative bearing surfaces were found to have a dislocation rate of 0.05%.51 Of note, investigators have recognized a relationship between cup diameter and dislocation risk in patients undergoing THA.52,53 This is likely related to the additional dead space around the acetabular component into which the femoral head can dislocate. Bipolar arthroplasty is a salvage option based upon a similar principle in which the overall range of motion is increased with articulation at two different bearing surfaces.54–57 The bipolar device itself is composed of a small femoral head housed inside a polyethylene shell that is covered by a large femoral head.20 As such, a safer arc of motion prior to dislocation occurs and the head-to-neck ratio is improved while providing a larger jump distance. Bipolars are seldom used now to solve hip instability in revision situations due to the risk of acetabular erosion and pain. However, bipolar implants, in combination with a fixed acetabular component, are used as a means of increasing effective head diameter. This approach can be particularly valuable when a well-fixed stem that does not accommodate a large diameter head is in place. Unconstrained tripolar hip arthroplasty (or dual-mobility systems) uses a bipolar head or a mobile partially constrained polyethylene head to articulate with an acetabular metal shell and liner. As such, the head-to-neck ratio and jump distance are increased. First introduced in the mid-1980s, such designs raise concern for particulate-induced osteolysis because there are two surfaces available as debris generators.55,58–61

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FIGURE 31-5. A: An elderly patient status post many hip operations with recurrent hip instability 14 years after complex hip revision. Components are well positioned, but soft tissue tension is suboptimal due to previous femoral nonunion that required some limb shortening to gain bone apposition for bone healing. B: Hip radiograph after revision to constrained tripolar acetabular liner.

Constrained implants provide immediate stability and may be the only viable solution when the entire abductor mechanism is deficient. These implants provide an excellent option for patients with recurrent dislocations of unknown etiology, elderly patients in whom the components are well fixed, and patients with neurologic impairment.20,57,62–65 However, there are serious drawbacks, including risk of disassembly, reduced range of motion to impingement, and increased stresses on bone-implant attachment interfaces (Fig. 31-7). This is due to the fact that constrained implants transfer high loads, which would otherwise lead to hip dislocation.6 In general, the more tenuous the implant fixation, the less desirable a constrained implant becomes. Furthermore, use of such an implant should be limited in the younger and more active patient. Concerns with constrained liners include premature wear, increased radiolucency, and dislodgment.20,66 Cooke et al.67 described three types of early failure of a constrained acetabular implant. Type-I failures occurred at the bone-prosthesis interface (three patients), Type-II failures included dysfunction

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in the liner locking mechanism (two patients), and Type-III failures occurred at the femoral head locking mechanism (one patient). Such failures can be minimized with supplemental screw fixation, seating the liner fully with scoring of the polyethylene (when the liner is cemented), and avoiding impingement, respectively. When dislocations of a constrained design occur, they can be difficult to manage and usually require surgical intervention. There are three main types of constrained implants, including snap-fit sockets, sockets with constraint provided by a metal locking ring around the periphery of a polyethylene, and constrained tripolar devices.6

RESULTS Closed Treatment Dorr and Wan68 found that 10 of 12 hips treated in a brace became stable. Likewise, Clayton and Thirupathi69 reported success in seven of nine patients

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FIGURE 31-6. A: Hip radiograph of a patient with recurrent hip instability after multiple hip operations including a proximal femoral allograft. The patient has notably deficient abductor muscles. B: Hip radiograph after revision to constrained acetabular component liner.

treated with longer term bracing. Ritter5 documented success in three of five hips treated in a hip spica cast. As noted above, bracing is useful for those patients who are experiencing their first-time dislocation. Stewart70 noted that only three of eight recurrent dislocations were treated successfully.

Component Repositioning Lewinnek et al.13 found that dislocation decreased from 6% to 1.5% when implants were placed within the safe zone. Moreover, Daly and Morrey9 reported 81% success rate (22 of 28 hips) when an unstable hip with insufficient acetabular anteversion was revised by socket repositioning. Elevated Liners Cobb et al.71 reviewed more than 5,000 THAs and compared neutral liners with 10 degree elevatedrim liners. He did note a reduction in dislocations from 3.85% to 2.19% (p = 0.001). In addition, McConway et al.72 reported a 1.6% dislocation rate in 307 patients treated with revision THA with a posterior lip augmentation device. Of note, a

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prerequisite for placement of an elevated liner in the above studies included well-positioned and well-fixed acetabular and femoral components. Alberton et al.73 found that elevatedrim liners significantly reduced the risk of dislocation compared with standard liners (2.6% vs. 8.0%, respectively) only when both components were revised. However, the design of elevated liners may lead to increased impingement in extension and external rotation, which may lead to increased linear wear, osteolysis, and loosening.

Modular Head and Liner Exchanges Mixed results have been reported with isolated modular liner and head exchange. Toomey et al.46 described 92% success in a series of 13 patients treated with exchange of the femoral head and/or acetabular liner. Of note, these revisions also included removal of soft tissue and bone resulting in impingement. In another study by Parvizi et al.,74 82% success was reported for treatment of late instability associated with polyethylene wear. On the other hand, several complications can occur with isolated

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head/liner exchanges. Barrack et al.75 described 15 complications that were related to failure at the modular interface, including detachment of the femoral head from the trunnion and dislodgment of the polyethylene liner from the shell. More recently, Carter et al.17 reported a high failure rate (34%) with isolated liner exchange. Lachiewicz et al.76 reported 18% and 50% dislocation rates after revision for instability in patients with primary and revision THA, respectively. Similar to elevated liners, the acetabular and femoral components must be well positioned and well fixed. Fehring et al.77 reported a 55% (16 of 29 patients) failure rate when patients with component malposition were treated with isolated modular head and liner exchanges.

Large Heads/Bipolar Similar to modular head and liner exchanges, the results of large femoral heads to treat hip instability are varied. Beaulé et al.78 reported >90% success at average follow-up for 6.5 years for patients treated with large

femoral heads (36 mm and larger) for hip instability. Amstutz et al.79 also reported optimistic results in 29 patients treated with jumbo heads for recurrent dislocations. On the other hand, Skeels et al.80 described a 17% rate of recurrent dislocation in patients who had undergone revision surgery with the use of a femoral head that was 36 mm or larger. In patients with developmental dysplasia of the hip, Wang et al.81 recently showed that femoral head size was the only significant difference between the dislocated and stable groups. In regard to cup size and larger heads, Peter et al.53 noted that dislocations were twice as likely with a cup size of 56 mm or higher (4.3% vs. 1.3%, respectively). The results of bipolar femoral prostheses are more promising, but at a cost.54,55,82 Zelicof and Scott reported that all 11 hips revised for instability were stabilized by conversion to a bipolar. Furthermore, Parvizi and Morrey reported a 93% success rate (25 of 27 hips) in restoring stability at a mean surveillance of 5 years. Attarian56 achieved 100%

FIGURE 31-7. Hip radiographs of a patient with previous history of recurrent instability. The patient has failed two previous constrained implants. One was a modern constrained device designed to minimize impingement (A) and one was a constrained tripolar device (B,C). (Figure continued on next page)

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FIGURE 31-7. (Continued) D,E: Hip radiographs after acetabular revision to an optimal position and to a nonconstrained, dual-mobility construct.

success using bipolar arthroplasty for instability. Nadaud et al.83 reported similar results with a successful outcome in 23 of 23 procedures. However, the bipolar femoral head articulates directly with acetabular bone and can cause pain and bone erosion.

Unconstrained Tripolar/Dual Mobility In general, the results of unconstrained tripolars (i.e., dual-mobility systems) have been favorable. Grigoris et al.84 reported that all eight hips treated for instability with a tripolar arrangement became stable. Beaulé et al.85 successfully treated instability in 95% of cases without compromising acetabular fixation using an unconstrained tripolar implant. Likewise, Levine et al.59 noted a 93% success rate in a series of 31 patients who had unstable THAs treated with an unconstrained tripolar construct. Guyen et al successfully treated 98.1% of 54 patients who were recurrently dislocating with a dual-mobility construct. Leiber-Wackenheim et al.86 from France recently reported 98.3% success in treating 59 recurrent total hip dislocations using a cementless dual-mobility cup.

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Constrained Implants Anderson et al.62 were the first to describe the use of constrained liners in patients with recurrent dislocation. They reported a success rate of 72% in a study of 18 patients followed for a mean of 31 months. Four of the six failures occurred with disassembly and disengagement of one specific design. Williams et al.87 reviewed 1,199 cases of hip instability treated with constrained liners from 8 different series. With a mean follow-up of 51 months, the authors found a 10% rate of dislocation and 4% rate of reoperation for other reasons. Callaghan et al. documented the clinical and radiographic outcomes of 31 revision THAs treated with a constrained liner that was cemented into a well-fixed cementless acetabular shell. At an average of 3.9 years postoperatively, 94% (29) of the constrained liners remained securely fixed.88 Similarly, Bremner et al.89 reported a 6% failure rate secondary to recurrent dislocation or liner failure at 10.2 years. Berend et al.90 reported a 99% success in terms of preventing recurrent dislocation in a group of 81 THA revisions done with a novel constrained device. Optimistic results regarding stability are tempered by other complications of constrained liners. While Shrader et al.66

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found that 98% of hip instability was successfully treated with a constrained liner, radiographic analysis revealed radiolucent lines around the cup in 15 hips (14%). At an average of 10.2 years after the use of 56 constrained tripolar devices, Goetz et al.91,92 reported a 7% failure rate secondary to recurrent dislocation, osteolysis, or aseptic loosening. Guyen et al. reported 43 failures of tripolar constrained devices, with four types of failure. They include failures at the bone-implant interface, the mechanism holding the constrained acetabular liner to the metal shell, the locking mechanism of the bipolar component, and dislocation of the head at the inner bearing.93

TECHNIQUES The specific techniques employed depend on the specific method and implant chosen. However, a number of general principles may be followed that are valuable in most cases. Before surgery, it is essential that the surgeon know exactly what implants are in place, because in most cases some parts of the old implants will be retained. This implies that compatible implants from the specific manufacturer, such as femoral heads or polyethylene liners, will need to be available. The surgeon also should have available implants that provide different solutions to instability problems, such as constrained, tripolar, or dual-mobility devices, in case they are needed. Finally as in all revisions, appropriate instruments to remove or disassemble existing implants should be available. Operative exposure is chosen to provide access to the arthroplasty as needed, avoid destabilization of the arthroplasty, and preserve muscle strength. Aspects of the tradeoffs involved in operative approach choice are described in Chapters 7 and 8. If greater trochanteric advancement may be required, it is important to avoid an anterolateral approach that detaches the abductor muscles. If implants must be removed from the bone, the methods described in Chapter 10 of this book are used. Priority is given to preserving bone stock to allow secure implant fixation of the next implant. When a liner needs to be cemented into a wellfixed existing metal shell, the methods described in Chapter 11 are used. Specific techniques for reconstruction of deficient soft tissues including the posterior capsule and abductors have been described, and the reader is referred to original source material by authors who developed and are expert in these techniques.94,95 Key principles of the procedure include (i) careful intraoperative assessment of the failed implants to understand the direction of instability and the likely causative factor(s); (ii) meticulous trialing of implants to make sure the proposed solution provides satisfactory restoration of stability and solves the existing instability problem; (iii) assessment during trialing to make sure a proposed solution does not lead to a new problem such as intraprosthetic impingement due to an elevated liner or overcompensation of implant position that leads to

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hip instability in the opposite direction from that which led to the operation; (iv) restoration of soft tissue tension as allowed by soft tissue integrity and leg length considerations; and (v) avoidance of extra-articular impingement (extra-articular impingement provides a very effective fulcrum to facilitate hip dislocation, and when soft tissue or bone that impinges is identified, it should, when possible, be removed).

POSTOPERATIVE MANAGEMENT In the majority of cases, patients are treated in a hip abduction brace for 6 to 12 weeks from the time of surgery. The patient is then instructed to avoid the mechanism suspected to place their hip at risk. Patients who experienced a posterior dislocation are instructed to avoid flexion, adduction, and internal rotation. Patients who experienced an anterior dislocation are instructed to avoid extension and external rotation.

REFERENCES 1. Eftekhar NS. Dislocation and instability complicating low friction arthroplasty of the hip joint. Clin Orthop Relat Res 1976;121:120–125. 2. Etienne A, Cupic Z, Charnley J. Postoperative dislocation after Charnley low-friction arthroplasty. Clin Orthop Relat Res 1978;132:19–23. 3. Morrey BF. Instability after total hip arthroplasty. Orthop Clin North Am 1992;23(2):237–248. 4. Rao JP, Bronstein R. Dislocations following arthroplasties of the hip. Incidence, prevention, and treatment. Orthop Rev 1991;20(3):261–264. 5. Ritter MA. Dislocation and subluxation of the total hip replacement. Clin Orthop Relat Res 1976;121:92–94. 6. Berry DJ. Unstable total hip arthroplasty: detailed overview. Instr Course Lect 2001;50:265–274. 7. Sanchez-Sotelo J, Berry DJ. Epidemiology of instability after total hip replacement. Orthop Clin North Am 2001;32(4):543–552, vii. 8. Ali Khan MA, Brakenbury PH, Reynolds IS. Dislocation following total hip replacement. J Bone Joint Surg Br 1981;63-B(2):214–218. 9. Daly PJ, Morrey BF. Operative correction of an unstable total hip arthroplasty. J Bone Joint Surg Am 1992;74(9):1334–1343. 10. Fackler CD, Poss R. Dislocation in total hip arthroplasties. Clin Orthop Relat Res 1980;151:169–178. 11. Garcia-Cimbrelo E, Munuera L. Dislocation in low-friction arthroplasty. J Arthroplasty 1992;7(2):149–155. 12. Kristiansen B, Jorgensen L, Holmich P. Dislocation following total hip arthroplasty. Archiv Orthop Traum Surg 1985;103(6):375–377. 13. Lewinnek GE, Lewis JL, Tarr R, et al. Dislocations after total hipreplacement arthroplasties. J Bone Joint Surg Am 1978;60(2):217–220. 14. Lindberg HO, Carlsson AS, Gentz CF, et al. Recurrent and nonrecurrent dislocation following total hip arthroplasty. Acta Orthop Scand 1982;53(6):947–952. 15. Woo RY, Morrey BF. Dislocations after total hip arthroplasty. J Bone Joint Surg Am 1982;64(9):1295–1306. 16. Kavanagh BF, Fitzgerald RH Jr. Multiple revisions for failed total hip arthroplasty not associated with infection. J Bone Joint Surg Am 1987;69(8):1144–1149. 17. Carter AH, Sheehan EC, Mortazavi SM, et al. Revision for recurrent instability: what are the predictors of failure? J Arthroplasty 2011;26(6 suppl):46–52. 18. Hedlundh U, Ahnfelt L, Fredin H. Incidence of dislocation after hip arthroplasty. Comparison of different registration methods in 408 cases. Acta Orthop Scand 1992;63(4):403–406.

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19. Woolson ST, Rahimtoola ZO. Risk factors for dislocation during the first 3 months after primary total hip replacement. J Arthroplasty 1999;14(6):662–668. 20. Parvizi J, Picinic E, Sharkey PF. Revision total hip arthroplasty for instability: surgical techniques and principles. J Bone Joint Surg Am 2008;90(5):1134–1142. 21. Williams JF, Gottesman MJ, Mallory TH. Dislocation after total hip arthroplasty. Treatment with an above-knee hip spica cast. Clin Orthop Relat Res 1982;171:53–58. 22. Joshi A, Lee CM, Markovic L, et al. Prognosis of dislocation after total hip arthroplasty. J Arthroplasty 1998;13(1):17–21. 23. Hedlundh U, Fredin H. Patient characteristics in dislocations after primary total hip arthroplasty. 60 patients compared with a control group. Acta Orthop Scand 1995;66(3):225–228. 24. Berry DJ, von Knoch M, Schleck CD, et al. The cumulative long-term risk of dislocation after primary Charnley total hip arthroplasty. J Bone Joint Surg Am 2004;86-A(1):9–14. 25. Bozic KJ, Kurtz SM, Lau E, et al. The epidemiology of revision total hip arthroplasty in the United States. J Bone Joint Surg Am 2009;91(1): 128–133. 26. Jafari SM, Coyle C, Mortazavi SM, et al. Revision hip arthroplasty: infection is the most common cause of failure. Clin Orthop Relat Res 2010;468(8):2046–2051. 27. Dorr LD, Wolf AW, Chandler R, et al. Classification and treatment of dislocations of total hip arthroplasty. Clin Orthop Relat Res 1983;173: 151–158. 28. Fraser GA, Wroblewski BM. Revision of the Charnley low-friction arthroplasty for recurrent or irreducible dislocation. J Bone Joint Surg Br 1981;63B-4:552–555. 29. Herrlin K, Selvik G, Pettersson H, et al. Position, orientation and component interaction in dislocation of the total hip prosthesis. Acta Radiol 1988;29(4):441–444. 30. Soong M, Rubash HE, Macaulay W. Dislocation after total hip arthroplasty. J Am Acad Orthop Surg 2004;12(5):314–321. 31. Amstutz HC, Lodwig RM, Schurman DJ, et al. Range of motion studies for total hip replacements. A comparative study with a new experimental apparatus. Clin Orthop Relat Res 1975;111:124–130. 32. Krushell RJ, Burke DW, Harris WH. Range of motion in contemporary total hip arthroplasty. The impact of modular head-neck components. J Arthroplasty 1991;6(2):97–101. 33. Coventry MB. Late dislocations in patients with Charnley total hip arthroplasty. J Bone Joint Surg Am 1985;67(6):832–841. 34. Pellicci PM, Bostrom M, Poss R. Posterior approach to total hip replacement using enhanced posterior soft tissue repair. Clin Orthop Relat Res 1998;355:224–228. 35. Goldstein WM, Gleason TF, Kopplin M, et al. Prevalence of dislocation after total hip arthroplasty through a posterolateral approach with partial capsulotomy and capsulorrhaphy. J Bone Joint Surg Am 2001;83-A(suppl 2 pt 1):2–7. 36. White RE Jr, Forness TJ, Allman JK, et al. Effect of posterior capsular repair on early dislocation in primary total hip replacement. Clin Orthop Relat Res 2001;393:163–167. 37. Turner RS. Postoperative total hip prosthetic femoral head dislocations. Incidence, etiologic factors, and management. Clin Orthop Relat Res 1994;301:196–204. 38. Vicar AJ, Coleman CR. A comparison of the anterolateral, transtrochanteric, and posterior surgical approaches in primary total hip arthroplasty. Clin Orthop Relat Res 1984;188:152–159. 39. Berry DJ, Harmsen WS. The cumulative risk of dislocation after revision total hip arthroplasty: time course, long-term risk, and risk factors. American Academy of Orthopaedic Surgeons. Dallas, TX, 2002. 40. McCollum DE, Gray WJ. Dislocation after total hip arthroplasty. Causes and prevention. Clin Orthop Relat Res 1990;261:159–170. 41. Bradbury N, Milligan GF. Acetabular augmentation for dislocation of the prosthetic hip. A 3 (1–6)-year follow-up of 16 patients. Acta Orthop Scand 1994;65(4):424–426.

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42. Mogensen B, Arnason H, Jonsson GT. Socket wall addition for dislocating total hip. Report of two cases. Acta Orthop Scand 1986;57(4): 373–374. 43. Olerud S, Karlstrom G. Recurrent dislocation after total hip replacement. Treatment by fixing an additional sector to the acetabular component. J Bone Joint Surg Br 1985;67(3):402–405. 44. Watson P, Nixon JR, Mollan RA. A prosthesis augmentation device for the prevention of recurrent hip dislocation. A preliminary report. Clin Orthop Relat Res 1991;267:79–84. 45. Krushell RJ, Burke DW, Harris WH. Elevated-rim acetabular components. Effect on range of motion and stability in total hip arthroplasty. J Arthroplasty 1991;(6 suppl):S53–S58. 46. Toomey SD, Hopper RH Jr, McAuley JP, et al. Modular component exchange for treatment of recurrent dislocation of a total hip replacement in selected patients. J Bone Joint Surg Am 2001;83-A(10):1529–1533. 47. Ekelund A. Trochanteric osteotomy for recurrent dislocation of total hip arthroplasty. J Arthroplasty 1993;8(6):629–632. 48. Kaplan SJ, Thomas WH, Poss R. Trochanteric advancement for recurrent dislocation after total hip arthroplasty. J Arthroplasty 1987;2(2):119–124. 49. Sariali E, Lazennec JY, Khiami F, et al. Mathematical evaluation of jumping distance in total hip arthroplasty: influence of abduction angle, femoral head offset, and head diameter. Acta Orthop 2009;80(3):277–282. 50. Berry DJ, von Knoch M, Schleck CD, et al. Effect of femoral head diameter and operative approach on risk of dislocation after primary total hip arthroplasty. J Bone Joint Surg Am 2005;87(11):2456–2463. 51. Lombardi AV Jr, Skeels MD, Berend KR, et al. Do large heads enhance stability and restore native anatomy in primary total hip arthroplasty? Clin Orthop Relat Res 2011;469(6):1547–1553. 52. Kelley SS, Lachiewicz PF, Hickman JM, et al. Relationship of femoral head and acetabular size to the prevalence of dislocation. Clin Orthop Relat Res 1998;355:163–170. 53. Peter R, Lubbeke A, Stern R, et al. Cup size and risk of dislocation after primary total hip arthroplasty. J Arthroplasty 2011;26(8):1305–1309. 54. Parvizi J, Morrey BF. Bipolar hip arthroplasty as a salvage treatment for instability of the hip. J Bone Joint Surg Am 2000;82-A(8):1132–1139. 55. Ries MD, Wiedel JD. Bipolar hip arthroplasty for recurrent dislocation after total hip arthroplasty. A report of three cases. Clin Orthop Relat Res 1992;278:121–127. 56. Attarian DE. Bipolar arthroplasty for recurrent total hip instability. J South Orthop Assoc 1999;8(4):249–253. 57. Berend KR, Sporer SM, Sierra RJ, et al. Achieving stability and lowerlimb length in total hip arthroplasty. J Bone Joint Surg Am 2010;92(16): 2737–2752. 58. Kim KJ, Rubash HE. Large amounts of polyethylene debris in the interface tissue surrounding bipolar endoprostheses. Comparison to total hip prostheses. J Arthroplasty 1997;12(1):32–39. 59. Levine BR, Della Valle CJ, Deirmengian CA, et al. The use of a tripolar articulation in revision total hip arthroplasty: a minimum of 24 months’ follow-up. J Arthroplasty 2008;23(8):1182–1188. 60. McClelland SJ, Godfrey JD, Benton PC, et al. Revision of failed hip surface replacement arthroplasties with a bipolar prosthesis. Three case reports with two- to three-year follow-up observations. Clin Orthop Relat Res 1986;208:243–248. 61. Scheerlinck T, Casteleyn PP. “Tripolar” hip arthroplasty for failed hip resurfacing: nineteen years follow-up. Acta Orthop Belg 2001;67(4): 407–411. 62. Anderson MJ, Murray WR, Skinner HB. Constrained acetabular components. J Arthroplasty 1994;9(1):17–23. 63. Lombardi AV Jr, Mallory TH, Kraus TJ, et al. Preliminary report on the S-ROM constraining acetabular insert: a retrospective clinical experience. Orthopedics 1991;14(3):297–303. 64. Padgett DE, Warashina H. The unstable total hip replacement. Clin Orthop Relat Res 2004;420:72–79. 65. Sanchez-Sotelo J, Haidukewych GJ, Boberg CJ. Hospital cost of dislocation after primary total hip arthroplasty. J Bone Joint Surg Am 2006;88(2):290–294.

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66. Shrader MW, Parvizi J, Lewallen DG. The use of a constrained acetabular component to treat instability after total hip arthroplasty. J Bone Joint Surg Am 2003;85-A(11):2179–2183. 67. Cooke CC, Hozack W, Lavernia C, et al. Early failure mechanisms of constrained tripolar acetabular sockets used in revision total hip arthroplasty. J Arthroplasty 2003;18(7):827–833. 68. Dorr LD, Wan Z. Causes of and treatment protocol for instability of total hip replacement. Clin Orthop Relat Res 1998;355:144–151. 69. Clayton ML, Thirupathi RG. Dislocation following total hip arthroplasty. Management by special brace in selected patients. Clin Orthop Relat Res 1983;177:154–159. 70. Stewart HD. The hip cast-brace for hip prosthesis instability. Ann R Coll Surg Engl 1983;65(6):404–406. 71. Cobb TK, Morrey BF, Ilstrup DM. The elevated-rim acetabular liner in total hip arthroplasty: relationship to postoperative dislocation. J Bone Joint Surg Am 1996;78(1):80–86. 72. McConway J, O’Brien S, Doran E, et al. The use of a posterior lip augmentation device for a revision of recurrent dislocation after primary cemented Charnley/Charnley Elite total hip replacement: results at a mean follow-up of six years and nine months. J Bone Joint Surg Br 2007;89(12):1581–1585. 73. Alberton GM, High WA, Morrey BF. Dislocation after revision total hip arthroplasty: an analysis of risk factors and treatment options. J Bone Joint Surg Am 2002;84-A(10):1788–1792. 74. Parvizi J, Wade FA, Rapuri V, et al. Revision hip arthroplasty for late instability secondary to polyethylene wear. Clin Orthop Relat Res 2006;447:66–69. 75. Barrack RL, Burke DW, Cook SD, et al. Complications related to modularity of total hip components. J Bone Joint Surg Br 1993;75(5): 688–692. 76. Lachiewicz PF, Soileau E, Ellis J. Modular revision for recurrent dislocation of primary or revision total hip arthroplasty. J Arthroplasty 2004;19(4):424–429. 77. Fehring TK, Griffin WL, Mason JB, et al. Failure of bloodless revision of the unstable total hip. American Academy of Orthopaedic Surgeons. Rosemont, IL; 2000:151. 78. Beaulé PE, Schmalzried TP, Udomkiat P, et al. Jumbo femoral head for the treatment of recurrent dislocation following total hip replacement. J Bone Joint Surg Am 2002;84-A(2):256–263. 79. Amstutz HC, Le Duff MJ, Beaule PE. Prevention and treatment of dislocation after total hip replacement using large diameter balls. Clin Orthop Relat Res 2004;429:108–116. 80. Skeels MD, Berend KR, Lombardi AV Jr. The dislocator, early and late: the role of large heads. Orthopedics 2009;32–39.

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81. Wang L, Trousdale RT, Ai S, et al. Dislocation after total hip arthroplasty among patients with developmental dysplasia of the hip. J Arthroplasty 2011. 82. Zelicof SB, Scott RD. Conversion to bipolar arthroplasty for the treatment of recurrent total hip dislocations: a two- to seven-year follow-up study. American Academy of Orthopaedic Surgeons. Rosemont, IL; 1992. 83. Nadaud MC, Fehring TK, Odum S, et al. Bipolar reconstruction for recurrent instability of the hip. Orthopedics 2004;27(7):746–751. 84. Grigoris P, Grecula MJ, Amstutz HC. Tripolar hip replacement for recurrent prosthetic dislocation. Clin Orthop Relat Res 1994;304:148–155. 85. Beaule PE, Roussignol X, Schmalzried TP, et al. Tripolar arthroplasty for recurrent total hip prosthesis dislocation. Revue de chirurgie orthopedique et reparatrice de l’appareil moteur 2003;89(3):242–249. 86. Leiber-Wackenheim F, Brunschweiler B, Ehlinger M, et al. Treatment of recurrent THR dislocation using of a cementless dual-mobility cup: a 59 cases series with a mean 8 years’ follow-up. Orthop Traumatol Surg Res 2011;97(1):8–13. 87. Williams JT Jr, Ragland PS, Clarke S. Constrained components for the unstable hip following total hip arthroplasty: a literature review. Int Orthop 2007;31(3):273–277. 88. Callaghan JJ, Parvizi J, Novak CC, et al. A constrained liner cemented into a secure cementless acetabular shell. J Bone Joint Surg Am 2004;86A(10):2206–2211. 89. Bremner BR, Goetz DD, Callaghan JJ, et al. Use of constrained acetabular components for hip instability: an average 10-year follow-up study. J Arthroplasty 2003;18(7 suppl 1):131–137. 90. Berend KR, Lombardi AV Jr, Welch M, Adams JB. A constrained device with increased range of motion prevents early dislocation. Clin Orthop Relat Res 2006;447:70–75. 91. Goetz DD, Capello WN, Callaghan JJ, et al. Salvage of total hip instability with a constrained acetabular component. Clin Orthop Relat Res 1998;355:171–181. 92. Goetz DD, Capello WN, Callaghan JJ, et al. Salvage of a recurrently dislocating total hip prosthesis with use of a constrained acetabular component. A retrospective analysis of fifty-six cases. J Bone Joint Surg Am 1998;80(4):502–509. 93. Guyen O, Lewallen DG, Cabanela ME. Modes of failure of Osteonics constrained tripolar implants: a retrospective analysis of forty-three failed implants. J Bone Joint Surg Am 2008;90(7):1553–1560. 94. McGann WA, Welch RB. Treatment of the unstable t otal hip arthroplasty using modularity, soft tissue, and allograft reconstruction. J Arthroplasty 2001;16(8 suppl 1):19–23. 95. Fehm MN, Huddleston JI, Burke DW, et al. Repair of a deficient abductor mechanism with Achilles tendon allograft after total hip replacement. J Bone Joint Surg Am 2010;92:2305–2311.

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32

Daniel J. Berry

Postoperative Periprosthetic Femur Fracture Around Total Hip Arthroplasty

INTRODUCTION TREATMENT AND RESULTS

INTRODUCTION Postoperative periprosthetic femur fractures can occur early or late after total hip arthroplasty (THA). Prosthetic retention is indicated for a selected group of postoperative periprosthetic fractures associated with a well-fixed, well-functioning implant. However, the majority of fractures occur in association with loosening of the implant, and prosthesis revision is indicated. This chapter focuses on revision for postoperative periprosthetic femur fractures, but also discusses the indications for and methods of internal fixation of periprosthetic femur fractures with associated prosthesis retention. The chapter does not discuss management of intraoperative periprosthetic fractures, a subject that is discussed in the chapter entitled “Management of Complications.” A section at the end of the chapter addresses the complex issue of management of periprosthetic fracture nonunion. Treatment of postoperative periprosthetic femur fractures has benefited greatly from two major advances: (1) the development of an excellent classification system, from which follows a general treatment algorithm that is well accepted by the orthopedic community; and (2) from markedly improved revision techniques and implants for these difficult problems. Nevertheless, simultaneously treating a femur fracture and a failed implant, which in combination require both effective fracture stabilization and femoral reconstruction with stable implants, remains a major technical challenge, and the potential for morbidity and mortality should not be discounted.1–6

Epidemiology Postoperative periprosthetic femur fractures occurred with an overall prevalence of 1.1% after 23,890 primary THA and 4% after 6,349 revision THA in a report for the Mayo Clinic.7 Lindahl et al.8 reported on 1,049 periprosthetic femur fractures from the Swedish National Hip

Register: patients with an underlying diagnosis of previous hip fracture or rheumatoid arthritis, both of which are associated with osteopenia, were at higher risk for postoperative fracture. The time from operation to periprosthetic fracture is highly variable, and fractures can occur as early as the first few days after surgery or as late as several decades after the operation. Early fractures are most commonly associated with either an undiagnosed intraoperative fracture or a proximally porouscoated uncemented implant that sustains a high load early after surgery—before implant osteointegration—leading to early fracture. Late fractures often are associated with implant loosening, osteoporosis, osteolysis, or trauma.

Classification Many classification methods have been proposed for periprosthetic femur fractures.9 The most widely used classification system is the so-called Vancouver Classification developed by Duncan and Masri (Fig. 32-1).10– 12 This classification system is particularly useful because it categorizes fractures based on anatomic location, implant fixation status, and bone quality13 These factors correlate with current treatment algorithms for periprosthetic fracture management.14–22 The Vancouver classification designates fractures in the peritrochanteric area as type A fractures, and divides this group into type A(G) fractures (fractures involving the greater trochanter) and type A(L) fractures (fractures involving the lesser trochanter). Type B fractures occur around the prosthesis stem or at its tip. These fractures are subclassified as type B1 fractures if associated with well-fixed implants, type B2 fractures if associated with a loose implant, and type B3 fractures if associated with a loose implant with severe proximal bone deficiency or comminution. Type C fractures are those that occur considerably distal to the tip of a THA component.

Treatment Algorithm Type A(G) fractures may occur in the presence of a well-fixed implant due to trauma. If the fracture is minimally displaced, nonoperative measures are appropriate, and healing can be anticipated in approximately 12 weeks. More commonly, these fractures occur in the setting of marked osteolysis of the greater trochanter, either with or without an episode of minor trauma. When the fracture is not markedly displaced, a period of time for healing (with 361

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Type B

Type A

L

Type B 2

1

around or just below stem-

at lesser trochanter

Type C

around or just below stem-

stem well fixed

stem loose

Type A

Type B 3

G

at greater trochanter

well below stem

at or just below stempoor bone stock in proximal femur

FIGURE 32-1. The Vancouver classification of periprosthetic femur fractures is the most widely used classification system. (Adapted from Duncan CP, Masri BA. Fractures of the femur after hip replacement. Instr Course Lect 1995;44:293–304, with permission.)

bony or fibrous tissue) usually is allowed before revision to manage the underlying particle-generating process that led to periprosthetic osteolysis. Markedly displaced acute greater trochanteric fractures are considered for early reoperation and fixation because nonoperative treatment is likely to lead to nonunion, an abductor limp, and possibly hip instability.23 However, gaining union of these fractures, even with operation, is difficult, and there is a risk of operative complications. Consequently the risk versus benefits of acute operative fixation of a greater trochanter should be considered carefully before a decision is made for operative intervention. Type A(L) fractures associated with a stable implant are rare and may be treated nonoperatively. Some A(L) fractures occur in the presence of local osteolysis, which eventually will require treatment for its own sake. Type A(L) fractures associated with a loose implant usually require femoral component revision. Vancouver type B1 fractures most commonly are treated with internal fixation and prosthesis retention.24 When internal fixation is chosen as a treatment method, it is important to ascertain with certainty that the prosthesis is well fixed.25

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A high rate of union with prosthesis retention now has been achieved using two different techniques. Vancouver type B2 fractures typically are treated with revision arthroplasty to simultaneously treat the fracture and the loose implant. Nonoperative treatment26 rarely is appropriate because of a high rate of nonunion and malunion and the prolonged immobility required. With modern implants and techniques, a single-stage procedure that includes fracture fixation and implant revision almost always is possible.27 Vancouver type B3 fractures may be treated with tumor prostheses, allograft prosthetic composites,28 or newer revision techniques using uncemented implants that gain axial and rotational stability distal to the implant. Vancouver type C fractures usually are treated with internal fixation using a retrograde intramedullary device or a plate. To avoid a high stress region that is subject to fracture between the stem tip and the new fixation device, overlapping of the fixation devices with the femoral component may be considered.

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TREATMENT AND RESULTS Vancouver Type A(G) Fractures Fixation of greater trochanteric fractures may be accomplished with wires, cables, suture, a cable grip claw, or cable plate.23 Preliminary experience with hook plates appears to be favorable for these difficult problems, and this technique may become the method of choice. These fractures often are transverse, and often involve a small piece of poor quality trochanteric bone; consequently, healing can be problematic. If healing fails, problems with pain, abductor insufficiency, and limp and hip instability are frequent. When operative treatment is selected for minimally displaced fractures associated with osteolysis, surgery frequently is delayed to allow the fracture to gain bony or fibrous union.29 By waiting 12 weeks or more, many of these fractures become sufficiently stable to allow reconstitution of a continuous sleeve of abductor, greater trochanter, and vastus lateralis before revision

363

surgery is undertaken to treat underlying wear and osteolysis problems (Fig. 32-2). If surgery is pursued acutely, the fracture typically is unstable and may become displaced, and fixation of the very thin osteolytic bone can be very difficult or impossible. Hsieh et al.30 reported on 21 greater trochanteric fractures associated with osteolysis that occurred a mean of 11 years after THA. Seventeen fractures were minimally displaced and 15 of the 17 treated nonoperatively with crutches, and activity restriction healed clinically and radiographically. Four of four fractures treated with internal fixation and bone grafting healed.

Vancouver Type A(L) Fractures A few A(L) fractures occur in the presence of a stable implant with associated periprosthetic osteolysis, and in such cases, elective surgery may be needed to manage the wear and osteolysis problems leading to fracture. Recently an A(L) fracture pattern associated with early failure of uncemented tapered collarless implants has been

FIGURE 32-2. A: Radiograph of hip with periprosthetic fracture of greater trochanter associated with osteolysis. B: The fracture was allowed to heal with fibrous tissue, and then revision to treat the polyethylene wear and osteolysis was performed. Note the sleeve of abductors—greater trochanter—vastus lateralis has remained in continuity.

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identified.31,32 These fractures may occur “spontaneously” with sudden hip loading or be associated with unidentified intraoperative fractures that subsequently displace under load. The typical fracture involves a single posterior-medial bone fragment that includes the lesser trochanter and is associated with a loose implant that has subsided and rotated into a retroverted position (Fig. 32-3). In most cases, early reoperation is indicated. The implant is extracted, the fracture is reduced, and a new implant is placed. A new short or medium-length uncemented stem (extensively porous coated or fluted tapered modular) that does not rely exclusively on the fractured proximal bone for support is indicated. Preliminary results of fixation of these fractures with cerclage and insertion of a new stem have been favorable. Taunton et al.32 reported that 25 of 28 such fractures healed and had a stable implant at followup. However, three patients required further operation, two for infection, and one for hip instability.

Vancouver Type B1 Fractures Vancouver type B1 fractures most commonly are treated with internal fixation, although on rare occasions internal fixation with prosthesis revision is indicated. The two keys to obtaining satisfactory results when treating these fractures are (1) a mechanically strong construct, and (2) respecting the vascularity of the bone. Historic experience has shown that cerclage fixation alone or plate fixation with unicortical proximal screws alone, both provide insufficient fixation. Better surgical techniques and internal fixation devices33,34 have improved results of fixation of these fractures.35,36

Technique. Plates designed for combinations of cerclage cable and screw fixation provide fixation proximal and distal to the implant tip (and the fracture).37 Two main methods currently are favored to treat these fractures. The first involves fixation with an allograft strut or struts,38–42 usually in combination with a plate (Fig. 32-4). Typically, a plate is placed laterally through a vastus lateralis splitting incision, and a cortical strut graft is contoured and placed anteriorly (Fig. 32-4). The most frequent mode of failure of these constructs is failure of proximal fixation (Fig. 32-5). For this reason, the author prefers to fix the plate with both cables and screws proximal to the fracture. Proximal screws can be placed either in a unicortical mode or a bicortical mode (posterior to the prosthesis). Proximal screws (in addition to cables) add substantial strength to the construct and improve both rotational strength and resistance to bending failure. The strut graft is held in place with at least two cables distally and usually at least two cables proximally. The plate— which is usually a locking screw plate43—is fixed to bone with screws distally (Fig. 32-6). Care is taken not to devascularize the fracture site and surrounding bone. Host bone graft, if available, may be placed carefully around the fracture medially, avoiding muscle stripping. A second technique, which recently has been reported to provide good results, is the so-called bridge plating technique. A plate is inserted with minimally invasive methods,

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extraperiosteally, through small incisions proximal and distal to the fracture site. The fracture is reduced using indirect reduction methods, and then the plate is secured to the bone with screws (usually locking screws). The key to this technique is minimal disruption of the blood supply to the fracture and maintenance of the fracture hematoma, which has growth factors that promote healing. High rates of union have been reported in several series with this technique.

Results. Treatment of Vancouver B1 fractures with internal fixation was reported by Lindahl et al.44 to have a high rate of failure in the Swedish National Hip Arthroplasty Register. These poor results in part are explained because some fractures were misclassified as type B1 type fractures when in fact they were associated with loose implants. However, the results also emphasize that older methods of internal fixation, especially a single (nonlocking) plate have a high failure rate, and are unsatisfactory for these difficult problems.45,46 Modern treatment with a plate and cortical strut graft or two strut grafts in combination have had a much higher success rate. Haddad et al.,1 in a multicenter study, reported fracture healing in 39 of 40 hips treated with one of these two methods. The combination of a plate and strut graft has been shown to provide more fixation than two struts in bench testing,47,48 but strut grafts alone for fixation have produced good clinical results in several series. Ricci et al.49 described use of a single lateral plate (usually a locking plate) in combination with indirect fracture reduction, extraperiosteal plate placement, and minimal soft tissue dissection. Fifty of 50 periprosthetic fractures healed in satisfactory alignment using this method.

Vancouver Type B2 Fractures The majority of periprosthetic fractures occur in the setting of implant loosening. Lindahl et al.,50 reporting on periprosthetic fractures in the Swedish National Hip Arthroplasty Register found 66% of fractures after primary THA and 50% of fractures after revision THA occurred in association with a loose stem. Vancouver type B2 fractures are treated with implant revision with concomitant fracture stabilization. Modern reconstruction methods take advantage of the fracture to provide access to the failed implant, using the fracture as a window to facilitate implant removal. Most commonly, the fracture is stabilized satisfactorily with a long-stem femoral implant and cerclage fixation, but when necessary, plates or cortical strut grafts may be added for additional fracture fixation. Improved femoral implants have greatly increased the success of one-stage revision of Vancouver B2 femur fractures.51 Almost all fractures now can be treated with a one-stage procedure at the time of the acute fracture. One-stage operation precludes the need for prolonged traction, or immobilization. Two-stage treatment, sometimes used historically, has the drawbacks of a high risk of malunion and nonunion, and ultimately producing more rather than less difficult reconstructions. Furthermore, two-stage treatment subjected patients to

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FIGURE 32-3. A: Radiograph of hip after primary THA with uncemented tapered collarless stem. B: Hip radiograph after the patient fell, sustaining a Vancouver A(L) fracture of the proximal femur. The stem has subsided and is loose. C: Hip radiograph after revision of the femoral component with standard length, extensively porous coated stem.

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FIGURE 32-4. Diagram of Vancouver type B1 periprosthetic femur fracture treated with a lateral plate and anterior cortical strut allograft. Note that the plate is fixed proximally with both screws and cables. (Modified Haddad FS, Duncan CP, Berry DJ, et al. Periprosthetic femoral fractures around well fixed implants: use of cortical onlay allografts with or without a plate. J Bone Joint Surg 2002;84A:945–950, with permission.)

long periods of immobilization that are poorly tolerated and led to a high risk of morbidity. A number of different modern femoral components may be used to reconstruct Vancouver type B2 fractures. Most North American surgeons now prefer to use uncemented implants in most cases because of their demonstrated high rate of success in revision THA (Figs. 32-7; 32-10; 32-13), and also because they avoid the problems of cement extrusion through the fracture site associated with cemented stems. Long cemented stems may be used in selected older or lower demand patients who have simple fracture patterns that can be anatomically reduced prior to cementation (to avoid cement extrusion) (Fig. 32-12).52 The most popular uncemented implants provide distal implant and bone fixation.51,53,54 Extensively porouscoated stems, fluted tapered modular stems, and stems with distal interlocking screws all have been used. Proximally

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FIGURE 32-5. Hip radiograph demonstrating failed internal fixation of a periprosthetic femur fracture. A single, lateral plate with only cable fixation proximally provided less fixation than more modern methods.

porous-coated modular implants with distal splines also may be used successfully in selected cases.

Technique. The hip is exposed according to the operative approach favored by the surgeon. The fracture is exposed directly by splitting the vastus lateralis. Stripping of muscle from bone is minimized to keep the fracture as vascular as possible. Loose stems (and cement) are removed using the fracture to access the implant directly, and an effort is made to avoid further comminuting the fracture during implant extraction. After implant removal, the surgeon must decide whether to first definitively reduce and stabilize the fracture or whether to prepare the femur for the new implant with the fracture still unreduced. Both methods are appropriate in different individual circumstances. If reduction and fixation before bone preparation is chosen, cerclage fixation typically provides satisfactory fixation. The femur then is prepared and an implant is inserted. A prophylactic cerclage cable or wire is placed just distal to the fracture to minimize risk of fracture propagation

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FIGURE 32-6. A: Hip radiograph demonstrating Vancouver Type B1 femur fracture in elderly woman with poor bone. B: Hip radiograph after internal fixation with lateral locking plate and anterior cortical strut bone graft. C: The fracture healed uneventfully. D: Although the acetabular component demonstrated wear, it was retained because of the patient’s age and very low activity.

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FIGURE 32-7. A: Hip radiograph demonstrating Vancouver type B2 femur fracture. B and C: Hip radiographs 2 years after revision THA with long uncemented extensively porous-coated femoral component. The fracture has healed, and the implant is bone ingrown.

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FIGURE 32-8. A: Hip radiograph demonstrating Vancouver type B2 femur fracture. B and C: Hip radiographs 5 years after revision THA with long fluted tapered modular uncemented femoral component. The fracture has healed, and stem is stable.

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FIGURE 32-9. A: Hip radiograph demonstrating Vancouver type B2 femur fracture. B: Hip radiograph 5 years after revision THA with long uncemented extensively porous-coated femoral component. The fracture has healed and the femoral component is bone ingrown.

when an uncemented distally fitting stem is impacted. If the implant is placed before final fracture reduction, the bone then is reassembled around the implant proximally after the implant is firmly anchored distally. In most cases, bone grafting is not needed if good blood supply to the bone has been maintained and if satisfactory fracture reduction with good bone apposition is achieved. However, allograft cortical struts may be used to treat notable segmental bone defects, or to help stabilize the fracture, when appropriate. Patient mobilization is immediate, but the patient typically is maintained at touchdown weight bearing for about 12 weeks until fracture consolidation and healing are evident.

Results. Historic results of treating periprosthetic fractures associated with implant loosening showed high failure rates due to implant loosening and other complications.55 In a series of 118 Vancouver type B2 and B3 fractures treated at the Mayo Clinic, Springer et al.56 reported that

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the Kaplan-Meier survivorship free of revision or removal of the femoral component for any reason was 90% at 5 years, 79% at 10 years, and 58% at 15 years. In one series, cemented stems had a 31% nonunion rate and a 15% refracture rate. Marked improvements in femoral revision implants, and in sophistication of revision hip arthroplasty techniques, have led to major improvements in the outcome of revision THA for fracture. In the Mayo Clinic series reported by Springer et al., uncemented extensively porous-coated stems had the best results, cemented stem intermediate results, and uncemented proximally porous-coated stems the poorest results. Of the 30 hips treated with uncemented extensively porous-coated stems, only one stem was revised for loosening and all fractures healed, a marked improvement from previous methods. Similar favorable results of extensively coated uncemented stems in revision have been reported by other authors.51,53,54 Fluted tapered uncemented stems

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FIGURE 32-10. A: Hip radiograph demonstrating Vancouver type B2 femur fracture. B: Hip radiograph 2 years after revision THA with long uncemented extensively porous-coated femoral component. The fracture has healed, and the implant is bone ingrown.

also have been used successfully in revision for Vancouver B2 periprosthetic femur fractures: Ko et al.57 reported success (healed fracture and stable implant) in 12 of 12 hips treated with a Wagner stem. Mulay et al.58 reported on 24 hips treated for Vancouver B2 and B3 fractures with a fluted tapered stem: 91% of fractures united and one hip became infected, but none loosened. Finally, impaction bone grafting to treat Vancouver type B2 and B2 periprosthetic femur fractures was reported in 106 hips by Tsiridis et al.59 The overall nonunion rate was 19.8%, but in patients specifically treated with long stems, the nonunion rate was only 12%.

Vancouver Type B3 Fractures Vancouver type B3 fractures represent the most challenging scenario because the implant is loose and proximal bone quality is too poor to provide reliable implant support. The thin weak proximal bone often is highly comminuted. The traditional method of treating these fractures has been with replacement of the proximal femur using either a proximal femoral allograft or a proximal femur replacing tumor prosthesis. Recently, an alternative approach has been developed using fluted tapered uncemented stems that have the unique advantage of providing rotational and axial stability in the diaphysis of the femur,

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and therefore not relying on the weak damaged proximal bone for either axial or rotational support60 (Fig. 32-13; 32-15). Because the proximal bone is not needed to support the prosthesis directly, limited manipulation, reduction, and fixation of the proximal bone is required, thereby maintaining bone vascularity and healing potential. Excellent proximal bone reconstitution has been reported in some small early series using this method.

Technique. The failed implant is exposed exclusively by splitting muscle and using established fracture lines or osteotomies to separate bone fragments. No muscle stripping from fracture fragments is performed. An attempt is made to retain fracture hematoma. The failed implants and cement are removed by separating the bone fragments. The distal femoral bone is examined to determine if it is satisfactory for uncemented component implantation. If the bone is too poor for an uncemented implant, a cemented tumor prosthesis (Chapter 28) is considered in an older patient. In most cases, a fluted tapered modular uncemented implant (Chapter 26) that provides axial and rotational stability in the diaphysis distal to the fracture is used. A prophylactic cerclage cable is placed just distal to the fracture site, and the femur is prepared to accommodate the uncemented stem. A trial implant is placed, and

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FIGURE 32-11. A: Hip radiograph demonstrating Vancouver type B2 femur fracture. B: Hip radiograph 5 years after revision THA with long fluted tapered modular uncemented femoral component. The fracture has healed, and stem is stable.

length and hip stability are ascertained. A radiograph may be obtained to confirm implant size and alignment. The new femoral component is impacted into the distal femur and tested to ensure that it has excellent axial and rotational stability. The appropriate length proximal modular implant segment and femoral head are assembled, and the hip is reduced. The shattered proximal bone fragments are drawn around the proximal implant—using the minimum amount of fixation needed to hold them in place—with cerclage wires, cables, or sutures. Maintaining vascularity is more important than perfect reduction of the many small bone fragments. The proximal implant is used as a scaffold for the assembled bone. An effort is made to hold the greater trochanter at the appropriate level using wires or sutures— affixing the greater trochanteric fragment either to the implant or to the distal bone (Fig. 32-11). Maintaining excellent blood supply to multiple shards of femoral bone during exposure, implant extraction, bone preparation, and reassembly of the bone around the proximal prosthesis is essential to maintain

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the vigorous biologic response that leads to bone healing and reconstitution (Figs. 32-14–32-16). Postoperatively, the patient is maintained at touchdown weight bearing until fracture healing is visible. Weight bearing usually can be progressed about 12 weeks after operation.

Results. Vancouver type B3 periprosthetic fractures represent some of the most difficult treatment problems, but several treatment strategies have produced encouraging results. Maury et al. 61 reported on 25 Vancouver B3 fractures treated with an allograft prosthetic composite; the re-revision rate was 16%. Twenty-three of twenty-five patients were able to walk at latest follow-up; 18 had a mild abductor lurch, 6 had a severe lurch, and 15 required a walking aid. Twenty-one patients treated for Vancouver type B3 fractures with a proximal femoral replacement tumor prosthesis were reported by Klein et al. 62 Twenty of twenty-one patients regained ambulatory capacity and reported no or minimal pain. Complications

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FIGURE 32-12. A and B: Hip radiographs demonstrating Vancouver type B2 femur fracture. C and D: Hip radiographs after revision THA with cemented stem. The cemented stem was chosen because of the patient’s age and the simple fracture pattern.

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FIGURE 32-13. A and B: Hip radiographs of a Vancouver type B2 femur fracture. There is limited bone available distal to the fracture for fixation. C and D: Hip radiographs after revision with extensively porous-coated femoral component. Note that a cortical strut allograft was placed on the lateral femur to add rotational stability to the construct and to protect the high stress area between prosthesis stem tips from a new fracture.

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FIGURE 32-14. Diagram showing technique of treating Vancouver type B3 femur fracture with a fluted tapered modular stem. (Mayo Foundation, with permission.)

FIGURE 32-15. A: Hip radiograph demonstrating Vancouver Type B3 femur fracture. B: Hip radiograph 1 year after revision with fluted tapered modular stem. Note the judicious use of fracture fixation to retain vascularity. The fracture has healed, and femoral component is stable.

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FIGURE 32-16. A: Hip radiograph demonstrating Vancouver type B3 femur fracture. B: Hip radiograph 3 years after revision THA with fluted tapered modular stem. The proximal bone fragment vascularity was carefully maintained. The plate on the distal femur was for treatment of a separate supracondylar femur fracture. Note excellent bone reconstitution.

included dislocation in two hips, infection in two hips, and refracture in one. A fluted tapered modular stem, with preservation of the proximal bone and its soft tissue attachments for treatment of severe Vancouver B3 fractures was reported from the Mayo Clinic at a minimum of 2 years’ follow-up. All fractures healed and all implants were stable. Notable bone stock reconstitution around the fracture was common. 60

Periprosthetic Femur Fracture Nonunions Periprosthetic femur fracture nonunion always represents a complex problem; typically, several previous hip operations have failed, there are failed implants (hip components, fixation hardware, or both), there is bone loss, and the patient has been disabled for a prolonged period of time.63

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Priorities in the treatment include making sure the hip is not infected, gaining new implant fixation, and effectively managing the nonunited bone. Screening serologic studies for infection are obtained, and in most cases, the hip is aspirated to rule out infection. Vancouver type B1 periprosthetic femur fracture nonunions previously treated with internal fixation are considered for either another internal fixation procedure or revision to a long-stemmed implant that bypasses the nonunion site. Refixation may be considered if initial fixation was clearly insufficient and if the remaining bone is satisfactory for internal fixation (Fig. 32-17). If refixation is attempted, the focus should be on gaining fixation better than that which failed and improving the biologic milieu with autogenous bone grafting and/or a cortical strut graft.

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FIGURE 32-17. A: Hip radiograph of periprosthetic femur fracture nonunion. B: Hip radiograph after repeat internal fixation with more robust proximal fixation demonstrating fracture healing. C: The stable femoral component was retained even though it was in varus alignment. Note use of proximal screws placed posterior to the femoral component to improve plate fixation.

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FIGURE 32-18. A: Hip radiograph demonstrating periprosthetic femur fracture nonunion. B: Hip radiograph after revision THA with fluted tapered modular uncemented stem. The stem is securely fixed in the distal bone, bypassing the nonunion site. The proximal femur was retained to maintain abductor function.

When the nonunion is associated with very poor bone quality (Fig. 32-18), or biologic circumstances adverse to bone healing (Fig. 32-19), plate fixation is unlikely to succeed, and revision is indicated. Implant removal may require an extended osteotomy, which in reality often means bivalving the proximal femur. Vancouver type B2 and B3 periprosthetic femur fracture nonunions usually are treated with another revision operation. The focus of revision is on gaining stable

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implant fixation distal to the fracture nonunion. A secondary goal is to reduce and fix the fracture and stimulate fracture union (Fig. 32-20). However, in some nonunion cases, healing is acknowledged to be unlikely. In these cases, the proximal femur may be left in situ and bypassed (recognizing it will not heal but is preserved by the bone for the sake of soft tissue attachments) or resected and substituted with a tumor prosthesis or allograft prosthetic composite (Figs. 32-21 and 32-22).

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FIGURE 32-19. A: Hip radiograph demonstrating periprosthetic femur fracture nonunion. B: Hip radiograph after revision THA with fluted tapered modular uncemented femoral component. C: A cortical strut graft was added to improve fracture stability and stimulate bone healing.

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FIGURE 32-20. A: Hip radiograph demonstrating periprosthetic femur fracture nonunion. B: Hip radiograph after revision THA with fluted tapered modular stem. The fracture was highly comminuted, marked bone loss was present, and fracture healing was not expected. The stem bypasses the fracture nonunion.

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FIGURE 32-21. A and B: Hip radiograph demonstrating periprosthetic femur fracture nonunion. The patient has had multiple operations and is elderly. C and D: Hip radiograph after revision THA with cemented tumor prosthesis substituting for proximal femur.

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FIGURE 32-22. A and B: Hip radiograph of patient with periprosthetic femur fracture nonunion. The patient has failed multiple previous operations. At operation, the fracture nonunion extended to the supracondylar area of the femur and bone was dysvascular. C and D: Hip radiograph after total femoral replacement. The likelihood of fracture healing was remote, and insufficient femoral bone remained to anchor to prosthesis in the distal femur.

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REFERENCES 1. Haddad FS, Duncan CP, Berry DJ, et al. Periprosthetic femoral fractures around well fixed implants: use of cortical onlay allografts with or without a plate. J Bone Joint Surg 2002;84A:945–950. 2. Jensen JS, Barfod G, Hansen D, et al. Femoral shaft fracture after hip arthroplasty. Acta Orthop Scand 1998;59:9–13. 3. Lindahl H, Oden A, Garellick G, et al. The excess mortality due to periprosthetic femur fracture. A study from the Swedish national hip arthroplasty register. Bone 2007;40:1294–1298. 4. Mont MA, Marr DC. Fractures of the ipsilateral femur after hip arthroplasty: a statistical analysis of outcome based on 487 patients. J Arthroplasty 1994;9:511–519. 5. Schmidt AH, Kyle RF. Periprosthetic fractures of the femur. Orthop Clin North Am 2002;33:143–152. 6. Younger AS, Dunwoody I, Duncan CP. Periprosthetic hip and knee fractures: the scope of the problem. Instr Course Lect 1998;47:251–256. 7. Berry DJ. Epidemiology: hip and knee. Orthop Clin North Am. 1999;30:183– 190. 8. Lindahl H, Malchau H, Herberts P, et al. Periprosthetic femoral fractures: classification and demographics of 1,049 late periprosthetic femoral fractures from the Swedish National Hip Arthroplasty Register. J Arthroplasty. 2005;20:857–865. 9. Johansson JE, McBroom R, Barrington TW, et al. Fracture of the ipsilateral femur in patients with total hip replacement. J Bone Joint Surg 1981;63:1435–1442. 10. Brady OH, Garbuz DS, Masri BA, et al. Classification of the hip. Orthop Clin North Am 1999;30:215–220. 11. Brady OH, Garbuz DS, Masri BA, et al. The reliability and validity of the Vancouver classification of femoral fractures after hip replacement. J Arthroplasty 2000;15:59–62. 12. Duncan CP, Masri BA. Fractures of the femur after hip replacement. Instr Course Lect 1995;44:293–304. 13. Berry DJ. Management of periprosthetic fractures: the hip. J Arthroplasty 2002;17:11–13. 14. Garbuz DS, Masri BA, Duncan CP. Periprosthetic fractures of the femur: principles of prevention and management. Instr Course Lect 1998;47:237– 242. 15. Kelley SS. Periprosthetic femoral fractures. J Am Acad Orthop Surg 1994;2:164– 172. 16. Kyle RF, Crickard GE III. Periprosthetic fractures associated with total hip arthroplasty. Orthopedics 1998;21:982–984. 17. Lee SR, Bostrom MPG. Periprosthetic fractures of the femur after total hip arthroplasty. Instr Course Lect 2004;53:111–118. 18. Lewallen DG, Berry DJ. Periprosthetic fracture of the femur after total hip arthroplasty: treatment and results to date. Instr Course Lect 1998;47:243–249. 19. Mitchell PA, Masri BA, Duncan CP. Periprosthetic fractures: classification and management. Tech Orthop 2001;16:291–309. 20. Ries MD. Periprosthetic fractures: early and late. Orthopedics 1997;20:798– 800. 21. Rorabeck CH. Periprosthetic fractures: a problem on the rise. Orthopedics 2000;23:989–990. 22. Sledge JB, Abiri A. An algorithm for the treatment of Vancouver type B2 periprosthetic proximal femoral fractures. J Arthroplasty 2002;17:887– 892. 23. Whiteside LA. Trochanteric repair and reconstruction in revision total hip arthroplasty. J Arthroplasty 2006;21(suppl 4):105–116. 24. Radcliffe SN, Smith DN. The Mennen plate in periprosthetic hip fractures. Injury 1996;27:27–30. 25. Lindahl H, Malchau H, Oden A, et al. Risk factors for failure after treatment of a periprosthetic fracture of the femur. J Bone Joint Surg 2006;88B:26–30. 26. Somers JF, Sui R, Stuyck J, et al. Conservative treatment of femoral shaft fractures in patients with total hip arthroplasty. J Arthroplasty 1998;13:162–171.

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27. Incavo SJ, Beard DM, Pupparo F, et al. One-stage revision of periprosthetic fractures around loose cemented total hip arthroplasty. Am J Orthop 1998;27:35–41. 28. Wong P, Gross AE. The use of structural allografts for treating periprosthetic fractures about the hip and knee. Orthop Clin North Am 1999;30:259–264. 29. Berry DJ. Periprosthetic fractures associated with osteolysis: a problem on the rise. J Arthroplasty 2003;18:107–111. 30. Hsieh PH, Chang YH, Lee PC, et al. Periprosthetic fractures of the greater trochanter through osteolytic cysts with uncemented Micro-Structured Omnifit prosthesis: retrospective analyses of 23 fractures in 887 hips after 5–14 years. Acta Orthop 2005;76:538–543. 31. Sarvilinna R, Huhtala HSA, Pajamaki KJK. Young age and wedge stem design are risk factors for periprosthetic fracture after arthroplasty due to hip fracture: a case-control study. Acta Orthop 2005;76:56–60. 32. Taunton MJ, Dorr LD, Long WT, et al. Early femur fracture after THA: increased prevalence associated with modern North American practice American Academy of Orthopaedic Surgeons Annual Meeting, 2008. 33. Serocki JH, Chandler RW, Dorr LD. Treatment of fractures about the hip prostheses with compression plating. J Arthroplasty 1992;7:129–135. 34. Tsiridis E, Narvani AA, Timperley JA, et al. Dynamic compressive plates for Vancouver type B periprosthetic femoral fractures. Acta Orthop 2005;76:531–537. 35. Agarwal S, Andrews CM, Bakeer GM. Outcome following stabilization of type B1 periprosthetic femoral fractures. J Arthroplasty 2005;20:118– 121. 36. Venu KM, Koka R, Garikipati R, et al. Dall-Miles cable and plate fixation for the treatment of peri-prosthetic femoral fractures-analysis of results in 13 cases. Injury 2001;32:395–400. 37. Haddad FS, Marston RA, Muirhead-Allwood SK. The Dall-Miles cable and plate system for periprosthetic femoral fractures. J Injury 1997;28:445–447. 38. Barden B, von Knoch M, Fitzek JG, et al. Periprosthetic fractures with extensive bone loss treated with onlay strut allografts. Int Orthop (SICOT) 2003;27:164–167. 39. Brady OH, Garbuz DS, Masri BA, et al. The treatment of periprosthetic fractures of the femur using cortical onlay allograft struts. Orthop Clin North Am 1999;30:249–257. 40. Chandler HP, King D, Limbird R, et al. The use of cortical allograft struts for fixation of fractures associated with well fixed total joint prostheses. Semin Arthroplasty 1993;4:99–107. 41. Chandler HP, Tigges RG. The role of allografts in the treatment of periprosthetic femoral fractures. Instr Course Lect 1998;47:257–264. 42. Wang JW, Wang CJ. Periprosthetic fracture of femur after hip arthroplasty the clinical outcome using cortical strut allografts. J Orthop Surg 2000;8:27–31. 43. Fulkerson E, Koval K, Preston CF, et al. Fixation of periprosthetic femoral shaft fractures associated with cemented femoral stems: a biomechanical comparison of locked plating and conventional cable plates. J Orthop Trauma 2006;20:89–93. 44. Lindahl H, Malchau H, Oden A, et al. Risk factors for failure after treatment of a periprosthetic fracture of the femur. J Bone Joint Surg 2005;88B:26–30. 45. Ahuja S, Chatterji S. The Mennen femoral plate for fixation of periprosthetic femoral fractures following hip arthroplasty. Injury 2002;33: 47–50. 46. Dave DJ, Koka SR, James SE. Mennen plate fixation for fracture of the femoral shaft with ipsilateral total hip and knee arthroplasties. J Arthroplasty 1995;10:113–115. 47. Dennis MG, Simon JA, Kummer FJ, et al. Fixation of periprosthetic femoral shaft fractures: a biomechanical comparison of two techniques. J Orthop Trauma 2001;15:177–180. 48. Dennis MG, Simon JA, Kummer FJ, et al. Fixation of periprosthetic femoral shaft fractures occurring at the tip of the stem: a biomechanical study of five techniques. J Arthroplasty 2000;15:523–528.

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49. Ricci WM, Bolhofner BR, Loftus T, et al. Indirect reduction and plate fixation, without grafting, for periprosthetic femoral shaft fractures about a stable intramedullary implant. J Bone Joint Surg 2005;87A:2240–2245. 50. Lindahl H, Regner H, Herberts P, et al. Three hundred and twentyone periprosthetic femoral fractures. J Bone Joint Surg 2006;88A: 1215–1222. 51. Macdonald SJ, Paprosky WG, Jablonsky WS, et al. Periprosthetic femoral fractures treated with a long-stem cementless component. J Arthroplasty 2001;16:379–383. 52. Larson JE, Chao EY, Fitzgerald RH. Bypassing femoral cortical defects with cemented intramedullary stems. J Orthop Res 1991;9:414–421. 53. Moran MC. Treatment of periprosthetic fractures around total hip arthroplasty with an extensively coated femoral component. J Arthroplasty 1996;11:981–988. 54. O’Shea K, Quinlan JF, Kutty S, et al. The use of uncemented extensively porous-coated femoral components in the management of Vancouver B2 and B3 periprosthetic femoral fractures. J Bone Joint Surg 2005;87B:1617–1621. 55. Beals RK, Tower SS. Periprosthetic fractures of the femur. An analysis of ninety-three fractures. Clin Orthop 1996;327:238–246. 56. Springer BD, Berry DJ, Lewallen DG. Treatment of periprosthetic femoral fractures following total hip arthroplasty with femoral component revision. J Bone Joint Surg 2003;85A:2156–2162.

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57. Ko PS, Lam JJ, Tio MK, et al. Distal fixation with Wagner revision stem in treating Vancouver type B2 periprosthetic femur fractures in geriatric patients. J Arthroplasty 2003;18:446–452. 58. Mulay S, Hassan T, Birtwistle S, et al. Management of types B2 and B3 femoral periprosthetic fractures by a tapered, fluted, and distally fixed stem. J Arthroplasty 2005;20:751–756. 59. Tsiridis E, Narvani AA, Haddad FS, et al. Impaction femoral allografting and cemented revision for periprosthetic femoral fractures. J Bone Joint Surg 2004;86B:1124–1132. 60. Berry DJ. Treatment of Vancouver B3 periprosthetic femur fractures with a fluted tapered stem. Clin Orthop 2003;417:224–231. 61. Maury AC, Pressman A, Cayen B, et al. Proximal femoral allograft treatment of Vancouver type-B3 periprosthetic femoral fractures after total hip arthroplasty. J Bone Joint Surg 2006;88A:953–958. 62. Klein GR, Parvizi J, Rapuri V, et al. Proximal femoral replacement for the treatment of periprosthetic fractures. J Bone Joint Surg 2005;87A: 1777–1781. 63. Crockarell JR, Berry DJ, Lewallen DG. Nonunion after periprosthetic femoral fracture associated with total hip arthroplasty. J Bone Joint Surg 1999;81A:1073–1079.

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CHAPTER

33

William Maloney

Periprosthetic Osteolysis INTRODUCTION Since the introduction of low-friction total hip arthroplasty by Sir John Charnley over four decades ago, millions of arthritis patients have experienced substantial pain relief and enhanced quality of life. Although advances in surgical technique, implant design, implant fixation, and antibiotic prophylaxis have contributed to short- and long-term success for the majority of patients, the challenge of achieving long-term durability for many others can be limited by their own biological response to particulate debris. Osteolysis refers to the process of bone resorption around either stable or unstable joint replacement prostheses.1,2 Charnley3 recognized this source of radiographic and clinical failure but felt that the process was related to culture-negative infection. Subsequent observers attributed the process as a reaction to polymethylmethacrylate (PMMA) cement,4,5 leading to the development of cementless implant technology. However, in spite of the elimination of PMMA with cementless reconstruction, the problems of aseptic loosening and focal osteolysis were not resolved.6–11 Over the past 20 years, the culmination of clinical and laboratory research has implicated particulate debris as the inciting cause and macrophage-mediated activation of osteoclastic bone resorption as the mechanism of both linear (aseptic loosening) and focal osteolysis. Although these two osteolytic variants bear different radiographic appearance, the underlying pathophysiology is currently understood to result from the same process.12 The recognition of the central role of particulate debris in the osteolytic process has directed interest into both alternative bearing surfaces and into enhancing the wear resistance of polyethylene in an effort to limit the generation of submicrometer-sized particles. Although preliminary results are encouraging, the effectiveness of these alternative bearing surfaces will not be fully delineated for several years. Within the context of revision total hip arthroplasty, understanding the process of osteolysis is important for planning appropriate surgical approaches for both linear osteolysis and clinically significant focal osteolysis around either wellfixed or loose implants. Preoperative and intraoperative assessment of implant fixation and periprosthetic bone support combine with surgical judgment in selecting the most appropriate reconstructive approach for each individual patient. The aim of this chapter is to outline the pathophysiological processes that result in osteolysis, to describe the clinical

and radiographic presentation of both linear and focal osteolysis, and to delineate surgical approaches that will most predictably address the underlying osseous deficiencies.

PATHOPHYSIOLOGY Generation of Particulate Debris Particulate debris can be generated by either mechanical wear or corrosion. General processes of mechanical wear include adhesion, abrasion, and fatigue.13 These mechanisms can occur at the articular bearing surface, the fixation interfaces, or from additional devices incorporated to enhance fixation (e.g., screws, wires, claws). Corrosion can occur between dissimilar materials,14 at modular component interfaces (e.g., Morse taper),14,15 or between implants and additional fixation devices.16 The types of particles that have been identified within periprosthetic membranes obtained at revision surgery reflect the materials used during the initial reconstruction: polyethylene, PMMA, titanium, cobalt-chromium, silicates, and stainless steel.17–21 McKellop et al.22 described the mechanical conditions underlying the generation of particulate debris as modes of wear. Mode 1 refers to expected wear that occurs at the primary articular bearing surface. Mode 2 wear occurs when the primary bearing contacts a secondary surface in an unintended fashion (e.g., femoral head penetration through a thin polyethylene liner). Mode 3 refers to third-body, abrasive wear. Mode 4 wear occurs between two nonbearing surfaces. Examples of mode 4 wear include backside wear, impingement of the Morse taper against the acetabular shell, and micromotion at modular connections or at the stem-cement interface. In the majority of appropriately aligned total hip replacements, the most significant source of wear should be mode 1, between the articular bearing surfaces.17 McKellop et al.22 estimated that as many as 500,000 submicrometer particles of polyethylene can be generated during each gait cycle. In failed total hip arthroplasties, either mode 1 wear rate may accelerate or additional modes of wear may contribute significantly to the generation of particulate wear particles. Motion at the interface between modular acetabular components,23–27 counterface abrasions,28 and generation of abrasive particulate debris22 have been associated with premature radiographic and clinical failure. Maloney et al.29 identified an average of 1.7 billion particles per gram of tissue within periprosthetic

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granulomas around loose cementless components in contrast to 143 million particles per gram of tissue around a control group of primary total hip replacements. In this study, the average size of particles reported was 0.5 mm for polyethylene and 0.7 mm for metal debris with 90% of all particulate debris