Tips and Tricks in Hip and Knee Arthroplasty [1 ed.] 9789386107497, 9789350256473

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Tips and Tricks in HIP AND KNEE ARTHROPLASTY

Tips and Tricks in HIP AND KNEE ARTHROPLASTY A Practical Approach Authors

Chandra Shekhar Yadav  MBBS MS (Ortho) Professor Department of Orthopedics Knee and Hip Arthroplasty Surgeon All India Institute of Medical Sciences (AIIMS) New Delhi, India Joint Replacement Fellow The Prince Charles Hospital, Brisbane, Australia King George Hospital Sydney, Australia Dartmouth-Hitchcock Medical Center New Hampshire, USA

Ashok Kumar  MBBS MS (Ortho) MRCS

Consultant Orthopedic Surgeon Department of Orthopedics (Joint Replacement, Pediatric Orthopedics, Oncology) Dubai Bone and Joint (DBAJ) Center Mohammed Bin Rashid Al Maktoum Academic Medical Center (BBRM-AMC) Dubai Healthcare City (DHCC) Dubai, UAE Fellow Exeter Hip Center, UK Trauma and Orthopedics Katharinen Hospital, Germany

Co-Author

Sanjay Yadav  MBBS MS (Ortho)

Senior Resident Department of Orthopedics Surgery All India Institute of Medical Sciences New Delhi, India

Foreword

Ross Crawford

JAYPEE BROTHERS MEDICAL PUBLISHERS (P) LTD. New Delhi • London • Philadelphia • Panama

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Website: www.jaypeebrothers.com Website: www.jaypeedigital.com © 2014, Jaypee Brothers Medical Publishers The views and opinions expressed in this book are solely those of the original contributor(s)/author(s) and do not necessarily represent those of editor(s) of the book. All rights reserved. No part of this publication may be reproduced, stored or transmitted in any form or by any means, electronic, mechanical, photo­copying, recording or otherwise, without the prior permission in writing of the publishers. All brand names and product names used in this book are trade names, service marks, trademarks or registered trademarks of their respective owners. The publisher is not associated with any product or vendor mentioned in this book. Medical knowledge and practice change constantly. This book is designed to provide accurate, authoritative information about the subject matter in question. However, readers are advised to check the most current information available on procedures included and check information from the manufacturer of each product to be administered, to verify the recommended dose, formula, method and duration of administration, adverse effects and contra­indications. It is the responsibility of the practitioner to take all appropriate safety precautions. Neither the publisher nor the author(s)/editor(s) assume any liability for any injury and/or damage to persons or property arising from or related to use of material in this book. This book is sold on the understanding that the publisher is not engaged in providing professional medical services. If such advice or services are required, the services of a competent medical professional should be sought. Every effort has been made where necessary to contact holders of copyright to obtain permission to reproduce copyright material. If any have been inadvertently overlooked, the publisher will be pleased to make the necessary arrangements at the first opportunity.

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Tips and Tricks in Hip and Knee Arthroplasty: A Practical Approach First Edition: 2014 ISBN: 978-93-5025-647-3 Printed at

Dedicated to My patients, well-wishers and family —Chandra Shekhar Yadav

My parents, loving wife (Sharda) sons (Anikait and Krish) and elder brother (Subhash) —Ashok Kumar My parents, wife (Swati) teachers and patients

—Sanjay Yadav

Foreword As hip and knee arthroplasty expands rapidly in India, it is important that training and junior surgeons develop an understanding of the principles of surgery. This book Tips and Tricks in Hip and Knee Arthroplasty: A Practical Approach offers an excellent introduction to the concepts and techniques of basic hip and knee arthroplasty. The book is well laid out with extensive illustrations, explaining the principles of arthroplasty, including surgical techniques and complications. I think, the book will be a very valuable aid for those developing their skills in hip and knee arthroplasty. I recommend the book to you as an excellent reference source for understanding hip and knee arthroplasty from the fundamental level to dealing with more complex primary joints replacements. Both the beginner and experienced surgeons will find much to enjoy in the book and will gain knowledge in some of the controversies in joint replacement surgery. The book does not choose to judge or present opinions on appropriate implant selections or techniques, but does provide a balanced approach to the pros and cons of different implant selections and surgical techniques.

Ross Crawford D Phil (Oxon) FRACS (Ortho) MBBS (Qld)

Professor (Orthopedic Research) Department of Biomedical Engineering School of Mechanical, Manufacturing and Medical Engineering Queensland University of Technology, Australia Director Department of Orthopedic Surgery Mater Adult Hospital South Brisbane Qld 4101, Australia

Preface It gives us immense pleasure to introduce the first edition of this book titled Tips and Tricks in Hip and Knee Arthroplasty: A Practical Approach. There are so many short books on the arthroplasty in the market, but usually they are focused in detail on one particular aspect of the arthroplasty. There was a need for a book which talks about simple practical approach to hip and knee arthroplasty. A book which gives all information from basic to the recent advances and current controversies in easily understandable language which even an orthopedic surgeon working in remote areas can understand and follow the concepts of the arthroplasty. By keeping these objectives in mind, the book has been written with sincere efforts. The book would be a great help for the postgraduates, residents, consultants and other surgeons who want to understand and learn the art of arthroplasty but may not be having a good mentor or shy to clear their doubts about arthroplasty because of their position, age or other reasons. The book cannot replace the standard textbooks of arthroplasty or orthopedics, but it will be of immense help as a handbook for the operation theater, indoor, outdoor clinical practice among budding arthroplasty surgeons.

Chandra Shekhar Yadav Ashok Kumar Sanjay Yadav

Contents Section 1: Hip Arthroplasty 1. Applied Anatomy

3

• Hip Joint  3

2. History and Biomechanics of Hip Arthroplasty

6

• Biomechanics  9

3. Implants and Bone Cements • • • • • •

Femoral Component  14 Acetabular Component  19 Ceramic on Ceramic Hips  21 Metal-on-metal Total Hip Arthroplasty  22 Hip Resurfacing vs Conventional THR  24 Bone Cements  24

4. Radiographic Evaluation in Total Hip Arthroplasty • • • • • • • • • •

14

28

Preoperative Radiological Evaluation  28 Radiographs  28 Acetabular Conditions, Precautions and Problem Faced  28 Femoral Conditions, Precautions and Problems Faced  31 CT Scan  34 Magnetic Resonance Imaging  35 Bone Scan  35 How to Read Postoperative X-Ray?  35 Follow-up Radiographs  38 Aseptic Loosening of Cup  38

5. Surgical Approaches and Indications of Hip Arthroplasty

41

• Conventional Surgical Approach  41

6. Perioperative Management of Total Hip Arthroplasty

50

• Preoperative Clinical Evaluation  50 • Postoperative Clinical Management  51

7. Primary Total Hip Arthroplasty • Neck Cut  54 • Exposure of Acetabulum  54

54

xii

Tips and Tricks in Hip and Knee Arthroplasty

• • • •

Acetabular Reaming  58 Femur Preparation  58 Impingement  67 Wound Closure  70

8. Complex Primary Total Hip Replacement

71

• Total Hip Replacement in Protrusio Hip  71 • Total Hip Replacement in Ankylosed Hip  73 • Dysplastic Hip  76

9. Complications of Total Hip Arthroplasty • • • • • •

79

Hematoma Formation  79 Mortality  79 Thromboembolism  80 Vascular Injury  81 Limb Length Discrepancy  81 Instability (Dislocation and Subluxation)  81

Section 2: Knee Arthroplasty 10. Applied Anatomy of Knee Joint

85

• Knee Joint  85

11. History and Biomechanics of Knee Arthroplasty

90

• Biomechanics of Normal Joint and a Prosthetic Joint  91

12. Implants and Patient Selection • • • • • • • • • • • • •

Osteoarthritis of Knee Joint  94 Treatment  95 Cruciate Retaining vs Cruciate Substituting  96 High Flex Design  98 Fixed vs Mobile Knee  99 Gender Knees  99 Cemented vs Noncemented  100 All Polyethylene vs Metal Backed Tibia  101 Routine vs Judicious use of Anticoagulant Prophylaxis  102 Patellar Resurfacing  103 Extension Rods  106 Hinged Implants  106 Various Conditions and Implant Selection  106

94

Contents

13. Perioperative Management of Total Knee Arthroplasty

xiii

111

• Preoperative Clinical Evaluation  111 • Postoperative Clinical Management  113

14. Surgical Approaches and Technique of Primary Total Knee Arthroplasty • • • • • •

116

Surgical Approaches  116 Tips of Patellar Eversion  123 Bone Cuts  123 Tibial Cut  123 Common Mistakes and their Causes  140 Criteria for Equalizing Flexion and Extension Gaps and Bone Cuts  145

15. Complex Primary Total Knee Arthroplasty

146

• Varus Knee  146 • Valgus Knee  147 • Fixed Flexion Deformity of Knee  148

16. Complications of Total Knee Arthroplasty

153

• Complications after Total Knee Replacement  153

Index 157.

157

Section

1

Hip Arthroplasty

1

chapter

Applied Anatomy

Hip Joint Type: Multiaxial ball and socket variety of the synovial joint.

Parts of Bones Forming Hip Joint zz

zz

zz

zz

zz

zz

zz

zz

Acetabulum: It lies on the lateral surface of pelvic bone where ilium, pubic and ischium bone fuse with each other. It has (Fig. 1.1) medial wall (floor, F), anterior (A), posterior (P) walls and the dome (D weight-bearing area). Inferiorly it is deficient and is called as the acetabular notch which is traversed by the transverse acetabular ligament (TAL). Acetabulum is 20° anteverted. Femur: Head of femur (Fig. 1.2) articulates with the acetabular cavity of pelvic bone. Neck is anteverted (15°) in relation to coronal plane. Capsule: It extends proximally to the acetabulum and transverse acetabular ligament, surrounds the femoral neck and is attached anteriorly down to the intertrochanteric line and posteriorly about 1cm above the intertrochanteric crest. Acetabular labrum: It is a fibrocartilaginous rim which elevates the peripheral margin of acetabulum and forms the transverse acetabular ligament. Movements: Flexion (0-130°), extension (0-20°), abduction (0-40°), adduction (0-30°), internal rotation (0-35°), external rotation (0-45°), and circumduction. Blood supply: Hip joint is supplied by the branches of the obturator artery, medial and lateral circumflex femoral arteries, superior and inferior gluteal arteries, and first perforating branch of the deep artery of the thigh. Inferior gluteal artery: It leaves behind the piriformis and its branch may be damaged while splitting the gluteus maximus muscle proximally. Blood supply to quadratus femoris: Branches of the lateral circumflex artery may bleed while cutting the quadratus femoris muscle.

4

Section 1  Hip Arthroplasty

Fig. 1.1  Anterior (A), posterior (P) walls, dome (D), floor (F) and transverse acetabular ligament (TAL) of the acetabulum; also the insertion of abductors (AB) at the tip of trochanter (T) and thigh

Fig. 1.2  The head (H, ball), acetabulum (Socket A), neck (N), greater trochanter (GT), lesser trochanter (LT), gluteus maximus (GM), attachment of the vastus lateralis (VL) at the base of greater trochanter and abductors (AB) being retracted at its attachment at the tip of greater trochanter with Hohmann retractor

Chapter 1  Applied Anatomy

Fig. 1.3  Tip of trochanter (TP), piriformis tendon (P), superior gemellus (SG), obturator internus (OI), inferior gemellus (IG), quadratus femoris (QF) and sciatic nerve (SN)

Nerve Supply It is supplied by femoral, obturator, superior gluteal nerves and by nerve to the quadratus femoris. Sciatic nerve: It leaves the pelvis through the greater sciatic notch and runs down the back of the thigh on the short external rotator muscles, encased in fatty tissue. The nerve crosses (Fig. 1.3) the superior gemellus (SG), obturator internus (OI), the inferior gemellus (IG), and the quadratus femoris (QF) before disappearing beneath the femoral attachment of the gluteus maximus.

5

2

chapter

History and Biomechanics of Hip Arthroplasty

History There are four different periods in the evolution of arthroplasty: 1. Early stage of total hip arthroplasty: Emphasis was on how arthroplasty can be performed successfully with different proposed materials (gold, fascia, glass, metal) and methods. • The first attempt to replace the hip joint was made by Gluck from Berlin (Germany, 1880) by using an ivory prosthesis.1 It was not successful. Second attempt was by French surgeon, Jules Pean from Paris (1890) with a platinum prosthesis. This prosthesis also failed. • Sir Robert Jones (1912) performed interpositional (using gold foils) hip arthroplasty. • Smith-Peterson (1921) performed mold arthroplasty (using glass) to restore congruous articular surfaces by inducing metaplasia in fibrin clot formed over exposed bleeding articular cancellous surfaces to fibrocartilage aided by gentle motion. Problem was glass breakage.2 • Modified Smith-Petersen cup arthroplasty (Aufranc) was the standard hip reconstruction method during this stage.2 2. Early modern total hip arthroplasty: Different types of prostheses became available but were associated with high rate of complications because of poor material and design. Bone cement and high density polyethylene were introduced. • Judet used heat-cured acrylic femoral head prosthesis. Problems were fragmentation and wear of acrylic head, tissue reactions and bone destruction.3 • Moore4 and Thompson5 used metallic endoprostheses and these were associated with acetabular erosion and femoral bone loss (Fig. 2.1). • Charnley6 introduced the concept of low frictional arthroplasty and used polyethylene with a cemented stem. Initial prosthesis consisted of a Teflon cup and stainless steel monobloc femoral components. Head size (Fig. 2.2) was 22.2 mm

Chapter 2  History and Biomechanics of Hip Arthroplasty

Fig. 2.1  Thompson and AMP prostheses, stem going into varus

Fig. 2.2  Charnley cemented prosthesis

Fig. 2.3  28 mm head with cementless total hip arthroplasty (AML stem-Diaphyseal/ Distal fit)

7

8

Section 1  Hip Arthroplasty

and prosthesis was fixed with polymethylmethacrylate (PMMA). Problems were ‘poly’ wear and aseptic loosening.6 3. Standard total hip arthroplasty: Metal on ultra-high density polyethylene with cementless (Fig. 2.3) or cemented stem became the standard modern THR implants: • Improved cementing technique • Large diameter heads were introduced (Fig. 2.4) • Press fit or porus coated, hydroxyapatite coated cementless stem were introduced. 4. Current total hip arthroplasty: Emphasis is on improving the bearing surfaces (metal, ceramic, highly crossed linked poly): • Metal-on-metal (cup, liner, head—all are metallic) (Fig. 2.4) • Metal-on-poly (metallic cup with highly crossed linked polyethylene liner on a metallic head) (Fig. 2.5) • Ceramic-on-poly (metallic cup, highly crossed linked polyethylene liner with ceramic head) • Ceramic-on-ceramic (ceramic liner with ceramic head with metallic cup) (Fig. 2.5).

Fig. 2.4  Large head Metal on Metal cementless THR

Chapter 2  History and Biomechanics of Hip Arthroplasty

Fig. 2.5  Ceramic-on-ceramic, metal-on-poly coupling with metaphyseal/proximal fit stem

Biomechanics Load on Hip Body weight acting on the hip in a single leg stance phace should be counterbalanced by the abductors by generating 2.5 times more force to maintain the position of pelvis. zz Normal hip: Ratio of the lever arm of the body weight to that of the abductors: 2.5:1 zz Arthritic hip: May be up to: 4:1 zz Prosthetic joint: Can be reduced up to 1:1 and it offloads hip up to 30% of the total load. Increasing the abductor lever arm reduces stress on joint.

Rotational Stability Rounded cemented femoral stem, broad proximal part, distal flutes, surface impressions and extensive porous coating improve rotational stability.

Center of Head (Hip Center) The anatomic position of center of head is most desirable position due to minimum stress on the joint. Medial or superolateral center of head produces more stress than the anatomic position. Center of rotation of head is determined by following three factors: 1. Vertical offset (Vertical height): Vertical distance from the center of the head to lesser trochanter (Fig. 2.6). Shortening of affected lower limb can be calculated by comparing this distance to opposite normal side in unilateral pathology. 2. Offset (Horizontal offset): Horizontal distance from the center of the femoral head to a line through the axis of the distal part of the stem or canal (Figs 2.7 and 2.8).

9

10

Section 1  Hip Arthroplasty

Fig. 2.6  Vertical offset (distance) from center of femoral head to lesser trochanter

Fig. 2.7  A = Horizontal offset, B = Vertical offset

Fig. 2.8  Horizontal offset (distance) from center of femoral head to tip of greater trochanter at right angle to axis through stem or canal

Chapter 2  History and Biomechanics of Hip Arthroplasty

3. Version of neck (Anterior offset): Position of neck in relation to the coronal plane. Normal anteversion: 10-15° (prosthetic joint should have the normal anteversion). Varus hips have reduced vertical offset and increased horizontal offset while valgus hip has increased vertical offset and reduced horizontal offset.

Head Diameter

Large Diameter Head More range of motion: Around 8-10° more flexion with 32 mm head than 28 mm.7 zz More stable: Has to move more distance before dislocation—‘jump distance’. zz Large head with trapezoidal neck (all current modern implants) produces less impingement than the 28 mm head with thick neck or skirted head (Plus size head) on a thick neck (circular or nonoval or nontrapezoidal neck). Current socket has a depth equal to radius of head and has beveled edges (both are absent in Charnley cup). So with large head, impingement is less and movement is more. zz

Coefficient of Friction It indicates amount of the resistance produced in moving one object over another. The coefficient of friction for normal joints: 0.008 – 0.02; metal-on-metal: 0.8; metal on high-density polyethylene: 0.02; ceramic-on-polyethylene is low; ceramicon-ceramic is nearly equal to normal joint.

Wear It is the loss of material from the moving surfaces of the prosthetic joint. It can be abrasive, adhesive and fatigue (more important in TKR). Three-body (third body) wear8 is an abrasive wear and occurs due to retention of debris particles between the sliding surfaces. Linear wear is measured by serial X-rays and better by digital radiographs and computer-assisted wear measurement. Cobaltchromium alloy head with a UHMWPE acetabular component usually has average wear of 0.10 mm/year.

Polywear Poly having a thickness below 5 mm usually has high risk of premature wear. Bigger head produces more volumetric wear and small head produces more point contact wear. But large head with highly crossed linked poly produces minimal poly wear. Cross-linking of polyethylene molecules by gamma radiation or electron beams is now known to substantially reduce wear of polyethylene bearings, with wear reduction proportional to the amount of cross-linking achieved. Second generation highly cross-linked poly like X3 poly (Stryker) uses sequential annealing to help saturate free radicals and EPoly (Biomet, Warsaw, IN) that uses vitamin E as a free radical scavenger have been introduced in the market. Advantages9 of highly cross-linked polyethylene include improved wear resistance, improved oxidative resistance, potentially lower susceptibility to third body wear, and maintenance of handling properties similar to the existing UHMWPEs. Reported mean wear rate with highly crosslinked poly is 0.022 and with UHMWPEs are 0.085 mm/y.9

11

12

Section 1  Hip Arthroplasty

Metal wear: Metal undergoes oxidative wear due to formation of surface passive oxide film, and with joint motion this film is repeatedly removed and reformed, with gradual roughening of the surface. Linear wear/year rate for metal-on-metal is 0.004 mm and metal-on-poly is 0.1 – 0.4 mm. Ceramic wear: Alumina and zirconia ceramics are harder than metal and exist in an oxide state; therefore, are not susceptible to oxidative wear. Linear wear/year rate for ceramic-on-poly is 0.05 – 0.1 mm and ceramic-on-ceramic is 0.002 mm. Lubrication: A thin film of fluid between metallic head and cup (boundary lubricant) reduces friction between the surfaces. Periprosthetic bone loss (Stress shielding): (Fig. 2.9) It is an adaptive bone remodeling occurring during first two years due to stress shielding (load is taken more by implant than the bone). It produces loosening (Fig. 2.9) and may predispose to fracture of the implant or of femur. It usually occurs around the proximal part of stem, stem with extensive porous coating or along the distal part of long stem. It is best detected by measurement of bone mineral density by DEXA scan. BMD shows a rapid fall around prosthesis during first 3-4 months and reaches a plateau around one year. Then it remains the same for next 5-6 years.10 Alendronate11 has been shown to reduce the periprosthetic bone loss. Preservation of subchondral bone, poly of more than 5 mm thickness and metal backed poly socket reduces acetabular component loosening.

Fig. 2.9  Gruen zones of osteolysis around proximal femoral prosthesis (zone 1 to 7)

Chapter 2  History and Biomechanics of Hip Arthroplasty

References 1. Fischer LP, Planchamp W, Fischer B, Chauvin F. The first total hip prostheses (1890) Hist Sci Med 2000; 34:51-70. 2. Smith-Petersen MN. Evolution of mould arthroplasty of the hip. J Bone Joint Surg 1948; 30:59-70. 3. Judet R, Judet J. Technique and results with acrylic femoral head prosthesis. J Bone Joint Surg Am 1952; 34:173-9. 4. Moore AT. The self-locking metal hip prosthesis. J Bone Joint Surg Am 1957; 39:811-20. 5. Thompson FR. Two and a half years’ experience with a Vitallium intramedullary hip prosthesis. J Bone Joint Surg Am 1954; 36:489-99. 6. Charnley J. Arthroplasty of the hip: a new operation. Lancet 1961; 1:1129-36. 7. Burroughs BR, Hallstrom B, Golladay GJ, et al. Range of motion and stability in total hip arthroplasty with 28, 32, 38 and 44 mm femoral head sizes: an in vitro study. J Arthropl 2005;20:11. 8. Bragdon CR, Jasty M, Muratoglu OK, et al. Third body wear of highly cross-linked polyethylene in a hip simulator. J Arthropl 2003;18:553. 9. Rajadhyaksha AD, Brotea C, Cheung Y, Kuhn C, PA-C, Ramakrishnan R, Zelicof SB. Fiveyear comparative study of highly cross-linked (crossfire) and traditional polyethylene. The Journal of Arthroplasty 2009; 24( 2): 161-7. 10. Venesmaa PK, Kröger HP, Jurvelin JS, et al. Periprosthetic bone loss after cemented total hip arthroplasty: a prospective 5-year dual energy radiographic absorptiometry study of 15 patients. Acta Orthop Scand 2003;74(1):31–6. 11. Tapaninen TS, Venesmaa PK, Jurvelin JS, Miettinen HJA, Kröger HPJ. Alendronate reduces periprosthetic bone loss after uncemented primary total hip arthroplasty – a 5-year follow-up of 16 patients. Scandinavian Journal of Surgery 2010; 99: 32–7.

13

3

chapter

Implants and Bone Cements

Femoral Component Femoral components are broadly divided into cemented and noncemented variety. Noncemented stems may have a porous surface for bone ingrowth or may be of pressfit varieties with surface impressions for macrointegration of bone with the implant. Vertical offset: It is determined by base length of the prosthetic neck plus the length added by the modular head (‘plus head’ increases and ‘minus head’ decreases the length). It is also affected (more in cemented hip) by the level of neck osteotomy and depth of stem inserted in femoral canal. Offset (horizontal offset): It is primarily a function of stem design. Some stems come in 132° (normal) and 127° (high) offsets. Anteversion: It is determined in relation to lesser trochanter and is less likely to change in cementless implant than cemented stem. Anatomical stem have some degree of inbuilt anteversion.

Cemented Stems Most commonly used stems are made up of cobalt-chrome alloy which has a high modulus of elasticity and it reduces stress in the proximal cement mantle. Lateral broad cross section of stem, loads the proximal cement mantle in compression. Collared stems are believed to help in deciding the depth of insertion. Initially stems having rough surface or impressions were believed to help in improving cement and implant bonding, but were later found to produce more debris and loosening. Currently polished collarless stems are the standard cemented femoral implant. Exeter stem is a polished collarless double tapered implant. Exeter stem is gold standard among the cemented stems. Examples of cemented stems are shown in (Fig. 3.1). Stems should occupy approximately 80% of the cross section of the medullary canal with an optimal proximal 4 mm and distal 2 mm of cement mantle (Fig. 3.2). Distal cement restrictor (usually 12-14 mm) or distal medullary plug and centralize

Chapter 3  Implants and Bone Cements

Fig. 3.1  Different cemented stems

Fig. 3.2  A well-fixed cemented exeter stem

15

16

Section 1  Hip Arthroplasty Table 3.1  Reported advantages and disadvantages of cemented and cementless hips Cemented hip

Cementless hip

Advantages

•  Gives immediate stability •  Allows fixation by direct bone-to-implant •  Allow immediate to early mobilization osteointegration •  Cement can fill the minimal femoral or acetabular bone loss/defects •  Revision is easy without need of bone grafting •  Cement related problems are not present •  Less expensive •  Limb length and femoral anteversion can be adjusted at the time of setting of bone cement

Disadvantages

•  Technically demanding (requires expertise in cementing techniques) •  Aseptic loosening (Fig. 3.3B) •  Cement fracture /breakage •  Cement related problem: Fat embolism •  Revision becomes difficult due to removal of cement and bone loss

A

•  More expensive than cemented hip •  3-6 weeks of nonweight bearing mobilization is required for osteointegration •  Sometimes stem removal difficult than cemented stem

B

Figs 3.3A and B  (A) Septic loosening of the cemented hip stem; (B) Aseptic loosening of the acetabular (arrow) and femoral components

Chapter 3  Implants and Bone Cements

the stem in the femoral canal and help in achieving uniform cement mantle. Usual length of currently available stem designs varies from 120 to >200 mm. Long stems are required in revision hip, or to bypass a cortical perforation, fracture or weak bone due to removal of screw or internal fixation devices. Advantages and disadvantages of cemented and cementless hip are given in Table 3.1. Figures 3.3A and B shows septic and aseptic loosening.

Cementless Stem It is indicated in active young adults, middle age and elderly patients with good bone stock. Definitive stability is provided by ingrowth of bone around the stem in the femoral canal. Most of them are proximal fitting stems. Very long stems (Fig. 3.5B) are distal fitting stem (used for revision hip). Two prerequisites for bone ingrowth include immediate implant stability at the time of surgery and intimate contact between the porous surface and viable host bone. Figure 3.4 shows various cementless stems. Uncemented porous coating: Commonly coated surface include titanium alloy with a porous surface of commercially pure titanium fiber-mesh or beads and cobalt-chromium alloy with a sintered beaded surface. Titanium has superior biocompatibility, high fatigue strength, and lower modulus of elasticity. But it is notch sensitive hence the porous coating should be restricted to large proximal part of the stem and should be avoided on

Fig. 3.4  Different cementless stems

17

18

Section 1  Hip Arthroplasty

A

B Figs 3.5A and B  (A) AML stems; (B) Solution stem

lateral tensile border of the stem. Problems include fatigue strength of porous implants, ion release, and adverse femoral remodeling. Extensive coating produces adverse femoral remodeling, stress shielding and thigh-pain (AML and Solution stems). Hence, it should be restricted to proximal portion only specially in primary arthoplasty). But fully coated stems are very useful in revision and osteoporotic bone where proximal or metaphyseal fitting is doubtful (Figs 3.5A and B). Cementless stems come in two following basic shapes: Anatomical femoral stem: It has a posterior metaphyseal bow and a variable anterior diaphyseal bow according to the geometry of the femoral canal. Anteversion must be built into the neck segment of separate right and left stems and slight overreaming is required for good fitting of implant. They are believed to transfer stress to large priority areas of contact mimicking the normal strain transfer patterns of the femur so have the long-term fixation. Straight femoral stem (Fig. 3.4): It has a symmetrical cross section and fit on either side. They may have proximal tapered large canal filling portion or may have parallel-sided, less proximal canal filling to achieve good fit (proximal and distal) and axial/rotational stability by virtue of their shape. They are believed to have better fit because of extra preparation of femoral canal.

Uncemented Press-fit Stems They have rough surface or surface impression that promotes macrointerlocking with bone after initial immediate surgical stability. They do not promote bone ingrowth without additional hydroxyaptite coating.

Modular Femoral Stem (Fig. 3.6) These stems are required for mismatch in fit at the proximal and distal part of stem. They have separate metaphyseal and neck part independent of diaphyseal portion.

Chapter 3  Implants and Bone Cements

Fig. 3.6  Versatile modular and custom made hip system

They are used in deformity of proximal femur due to surgery, trauma and congenital bowing and revision hip replacements.

Custom-made Femoral Components (Fig. 3.6) Patients having bony deformity or bone loss from trauma, tumor, congenital conditions (DDH requires small stems) or revision surgery (calcar replacement prosthesis) require custom made or specialized femoral components.

Acetabular component Broadly divided into cemented or cementless cup.

Cemented Cup (Fig. 3.7) Long-term survivorship is still questionable especially in beginners. Hence, these are preferred in elderly low demand patients, tumor surgery, severe osteopenic bone and revision surgery (requiring extensive bone grafting). But this is used in all age groups in many parts of the world. Cup has thick ultra high density (UHD) polyethylene with peripheral flange to pressurize the cement mantle, vertical and horizontal grooves on external surface to stabilize cement mantle and wire marker embedded in the plastic for assessomg the cup position in postoperative radiographs. Surface PMMA spacer of 3 mm helps in formation of a uniform cement mantle and prevents “bottoming out phenomenon” (cement gets pushed out below the cup and results in thin cement mantle).

19

20

Section 1  Hip Arthroplasty

Fig. 3.7  Exeter cemented cup with raised PMMA spacers

Fig. 3.8  Cementless acetabular cup

Cementless Acetabular Components (FIg. 3.8) Porus coated cementless cup with a UHD polyethylene or crossed linked polyethylene have become the standard in current modern cementless total hip arthroplasty. Bone integration is facilitated by initial fixation (integration occur maximum around

Chapter 3  Implants and Bone Cements

this) with screw, peg/spikes, or by enlarged peripheral press fitted rim without screw. Size ranges from 40 to 75 mm with polyethylene to articulate with different head diameters (22 to 36 mm). Polyethylene is secured with the cup by plastic flanges and metal wire rings that lock behind elevations or ridges in the metal shell, and peripherally placed screws. Thickness of the polyethylene should be > 5 mm to reduce wear hence acetabular loosening. Usually, polyethylene has a posterosuperior elevation (flanged portion of polyethylene liner) which gives additional stability. It should be positioned in either posterosuperior or superior position.

Ceramic on Ceramic Hips (FigS 3.9A and B) Materials related advantages and problems in old and current designs with ceramic implants are shown in Table 3.2.

Squeaking Sounds The incidence of squeaking with alumina-ceramic devices reported in the literature varies widely (0.3 to 20.9% ).4,5,7 Basic etiology: Study of the retrieved implants have shown microseparation, edge loading, and the development of stripe wear as three possible reasons for squeaking sound.8

Table 3.2  Reported material related advantages and problems with ceramic implants Old design

Current design (1994 onward; third generation)

Material

Faulty materials1,2 •  High porosity •  Larger grain size •  Low density of the ceramic

Better materials3 •  Higher density •  Higher purity •  Smaller grains

Problems

•  High fracture rate (13.4%) •  Osteolysis2

•  Low fracture rate (4:100 000 or 0.004%.)3 •  Squeaky sound (0.3%–20.9% )4,5 •  Osteolysis (1.4%)6

Fig. 3.9A  Ceramic on ceramic hip

Fig. 3.9B  Ceramic on polyethylene hip

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Section 1  Hip Arthroplasty

Following three factors may contribute to the above three basic reasons for production of squeaking sound:9 zz Surgical technique related factors: Improper orientation of the component may lead to decreased lubrication at the articulating interface or cause an obstruction leading to sound due to contact stress vibrations. This sound may be further exaggerated due to insufficient anteversion of the cup, impingement, or thirdbody debris in the interface. zz Patient related factors: These include younger age, increased height and weight, and high physical activity. zz Implant related factors: Implant design and the material also play an important role. Delta (Ceramtec) has been shown to produce less sound than Forte (Ceramtec) ceramic.

Click Sounds Possible causes include movement of a hard-on-hard bearing, soft tissue impingement, or shifting.7

Metal-on-Metal Total Hip Arthroplasty (Fig. 3.10) Potential advantages of metal-on-metal hips include use of large head (better stability and improved range of motion) and reduced rate of wear and osteolysis.10,11 Disadvantages includes elevation of serum and urine metal ion levels, possible risk of carcinogenicity and teratogenic effects in human beings,12 metal induced hypersensitivity13 reactions and diffuse or perivascularity oriented lymphocytic infiltration with early local inflammation and pain (ALVAL-Aseptic Lymphocyte-Dominated

Fig. 3.10  Resurfacing (MOM) implants

Chapter 3  Implants and Bone Cements Table 3.3  Reported advantages and disadvantages of the hip resurfacing vs conventional THR Hip resurfacing

Conventional THR

Advantages

•  Preservation of bone stock on femoral side 14,15 •  Less stress shielding 16,17 •  Less thigh pain 18 •  Reduced dislocations 18 •  Reduced osteolysis 19 •  Improved biomechanics 19 •  Retention of proprioception •  Easy revision on femoral side

•  Technically less demanding •  Problems of head retention are not seen (fracture neck of femur, osteonecrosis of head of femur) •  Less expensive (some implants) •  Large head (36 mm) with highly cross linked polyethylene give comparable hip movements, stability and durability

Disadvantages

•  Learning curve •  Range of motion is less than surface replacement in < 36 mm head •  Fracture of neck of femur (0 to 4%) •  More possibility of dislocation in small heads (0.4% to 5%) •  Malalignment •  Aseptic loosening •  Unexplained hip pain •  Increased revision rate due to complications associated with learning curve •  Osteonecrosis of head of femur •  Problems of metal-on-metal articulation

A

B Figs 3.11A and B  Complications of resurfacing

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Section 1  Hip Arthroplasty

Vasculitis-Associated Lesion) and ultimately metallosis and failure. ASR (DePuy Orthopedics) has been withdrawn from the market.20

Hip Resurfacing vs Conventional THR (FIg. 3.11) Initial reports of metal-on-metal hips were dramatic but slowly the faults associated with this technique started appearing in the literature. Initial literature was more in favor of resurfacing but now sufficient literature shows either a comparable or inferior result in comparison to conventional THR (Table 3.3). Now these implants have been withdrawn from the market. Fracture neck of femur: It is a very disturbing complication (Figs 3.11A and B) of surface replacement. Surgeon’s experience appears to be the most important factor for this complication. Other contributing factors include age, sex, body mass index, femoral neck notching, cysts on the femoral head, neck lengthening, and varus alignment of the femoral component.21

Bone Cements (Figs 3.12a and b) There are following three types of bone cement based on their viscosity: 1. Low viscosity: It has a long waiting phase (sticky phase) of 3 minutes; viscosity rapidly increases during the working phase and has a hardening phase of about 1-2 minutes. Surgeon has to act quickly for cementing. 2. Medium viscosity: It has a long waiting phase of 3 minutes; viscosity increases slowly during working phase and has a hardening phase between one minute 30 seconds and two minutes 30 seconds. 3. High viscosity: It has a short waiting phase followed by a long working phase. Viscosity remains same till the end of the working phase. Surgeon gets more time for cementing. The green color of Palacos Cement is believed to have reduced waiting time for dough-up and its green color gives better visibility. Simplex P is believed to have a better fatigue strength and Simplex P Speed Set cement has better strength and a faster setting time. Low viscosty cements are used in THR with cement gun

A

B Figs 3.12A and B  Cement mixing technique

Chapter 3  Implants and Bone Cements

(CMW 3). High viscosity cements are used in TKR with digital application (CMW 1). Low temperature (during storing and mixing) and high humidity prolongs setting time while high temperature speeds up the setting of bone cement. Temperature during hardening phase may increase up to 70°C to 120°C (in vitro) and up to 56°C (in vivo for 2-3 minutes).

A Fig. 3.13A  Distal medullary plug

B Fig. 3.13B  Distal centralizer in femoral cemented stem

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Section 1  Hip Arthroplasty

C Fig. 3.13C  Use of cement gun, retrograde filling

Functions of bone cement: It helps in fixation of components, reinforces the bone structure, transfers the mechanical stress to bone and may deliver antibiotic (if impregnated with cement). Modern cementing techniques (Figs 3.13A to C) include pulsatile lavage, medullary brush (to remove free bone, blood or debris), cement restrictor (for distal blockage of cement) Fig. 3.13A, packing of medullary canal with gauze tape soaked in hydrogen peroxide, medullary centralizer over distal tip of stem (to centralize stem in the canal) Fig. 3.13B, cement preparation (reduction of porosity by vacuum mixing, centrifugation), and cement gun for retrograde insertion and pressurization Fig. 3.13C. Complications of bone cement includes pulmonary embolism due to fat or cement pressurization (more in elderly patient or having patent foramen ovale); aseptic loosening and breakage.

References 1. Nizard R, Sedel L, Hannouoche D, et al. Alumina pairing in total hip replacement. J Bone Joint Surg Br 2005;87B:755. 2. Sedel L, Nizard R, Bizot P. Osteolysis and ceramic bearing surfaces. Clin Orthop 1998;349:273. 3. Joseph W. Greene, Arthur L. Malkani, Frank R. Kolisek, Nenette M. Jessup, MPH, Dale L, Baker BA. Ceramic-on-ceramic total hip arthroplasty. The Journal of Arthroplasty Vol. 24 No. 6 Suppl. 1 2009. 4. Walter WL, O’toole GC, Walter WK, et al. Squeaking in ceramic-on-ceramic hips: the importance of acetabular component orientation. J Arthroplasty 2007;22:496. 5. Keurentjes JC, Kuipers RM, Wever DJ, et al. High incidence of squeaking in THAs with alumina ceramic-on-ceramic bearings. Clin Orthop Relat Res 2008;466:1438. 6. D’Antonio JA, Capello WN, Manley MT. Alumina ceramic bearings for total hip arthroplasty: five-year results of a randomized study. Clin Orthop 2005;436:164.

Chapter 3  Implants and Bone Cements 7. Jarrett CA, Ranawat AS, Bruzzone M, et al. The squeaking hip: a phenomenon of ceramic-on-ceramic total hip arthroplasty. J Bone Joint Surg Am 2009;91:1344. 8. Glaser D, Komistek RD, Cates HE, et al. Clicking and squeaking: in vivo correlation of sound and separation for different bearing surfaces. J Bone Joint Surg Am 2008;90 (Suppl 4):112. 9. J Wesley Mesko, James A D’Antonio, William N Capello, Benjamin E Bierbaum, Marybeth Naughton. Ceramic-on-ceramic hip outcome at a 5- to 10-year interval has it lived up to its expectations? The Journal of Arthroplasty Vol. 00 No. 0 2010. 10. Schmalzried TP, Peters PC, Maurer BT, et al. Long duration metal-on-metal total hip arthroplasties with low wear of the articulating surfaces. J Arthroplasty 1996;11:322. 11. Sieber HP, Rieker CB, Kottig P. Analysis of 118 second-generation metal-on-metal retrieved hip implants. J Bone Joint Surg 1999;80B:46. 12. Brodner W, Bitzan P, Meisinger V, et al. Serum cobalt levels after metal-on-metal total hip arthroplasty. J Bone Joint Surg Am 2003;85-A:2168. 13. Willert HG, Buchhorn GH, Fayyazi A, et al. Metalon- metal bearings and hypersensitivity in patients with artificial hip joints. A clinical and histomorphological study. J Bone Joint Surg Am 2005; 87:280. 14. Mont MA, Ragland PS, Etienne G, et al. Hip resurfacing arthroplasty. J Am Acad Orthop Surg 2006;14: 454. 15. Crawford JR, Palmer SJ, Wimhurst JA, et al. Bone loss at hip resurfacing: a comparison with total hip arthroplasty. Hip Int 2005;15:195. 16. Harty JA, Devitt B, Harty LC, et al. Dual energy X-ray absorptiometry analysis of periprosthetic stress shielding in the Birmingham resurfacing hip replacement. Arch Orthop Trauma Surg 2005;125:693. 17. Little JP, Taddei F, Viceconti M, et al. Changes in femur stress after hip resurfacing arthroplasty: response to physiological loads. Clin Biomech (Bristol, Avon) 2007;22:440. 18. Wagner M, Wagner H. Preliminary results of uncemented metal-on-metal stemmed and resurfacing hip replacement arthroplasty. Clin Orthop Relat Res 1996(329 Suppl);S78 19. Treacy RB, McBryde CW, Pynsent PB. Birmingham hip resurfacing arthroplasty. A minimum follow-up of five years. J Bone Joint Surg Br 2005;87:167. 20. Marker DR, Seyler TM, Jinnah RH, et al. Femoral neck fractures after metal-on-metal total hip resurfacing: a prospective cohort study. J Arthroplasty 2007;22(Suppl 3):66. www.depuy.com/asr-hip-replacement-recall. Accessed on 17-10-2013.

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chapter

Radiographic Evaluation in Total Hip Arthroplasty

Preoperative radiological evaluation Radiographs zz zz

Anteroposterior radiograph of pelvis with both hips and proximal two-third of femur Lateral radiograph of hip with femur.

Confirm the diagnosis and assess the extent of pathology.

Acetabular Conditions, Precautions and Problem Faced Dysplasia (Fig. 4.1) Dysplastic small shallow acetabulum with deficient roof. There is lateral uncovering of femoral head due to absence of bone in posterosuperior part of acetabulum with or without evidence of previous iliac surgery (Salter’s/Pemberton osteotomy or commonly done shelf procedure). Think of using small cup with or without posterosuperior bone graft, medialization of hip center and difficulty in reduction.

Protrusio (Fig. 4.2) It is the projection of medial acetabular wall beyond the ilioischial line (Kohler line). Assess the degree (type 1: < 5 mm, type 2: 5-10 mm, type 3: >15 mm) of protrusion. Think of difficult dislocation of hip, lateralization of hip center with bone grafting of medial wall. Use the cup with wider periphery like PSL cup of stryker.

Chapter 4  Radiographic Evaluation in Total Hip Arthroplasty

Fig. 4.1  Dysplastic left hip with short limb (SL), upridden greater trochanter (UT), shallow acetabulum, increased acetabular index (AI), uncoverage of the head and sciatic nerve proximity

Fig. 4.2  Protrusion of medial wall (thin white arrow) of acetabulum beyond Kohler line (blue line). Severity is assessed with its distance (red line) from Kohler line

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Section 1  Hip Arthroplasty

Bone Quality (Fig. 4.3) Whether it is good or poor (osteopenia/osteoporosis). Think of gentle reaming, gentle impaction of the trial or definitive cup with or without bone grafting in osteoporotic hips.

Bone Loss Small or large cystic cavities. Think of curettage and bone grafting (simple/impacted).

Infection (Healed; Fig. 4.3) May have poor bone quality, bone loss, wandering acetabulum (high hip center), limb length discrepancy, protrusion with or without dysplasia.

Old Surgically Treated or Conservatively Treated Fracture of Acetabulum (Figs 4.4A and B) May have protrusion, poor bone quality, bone loss, medial or high hip center with or without limb length discrepancy. Think of above-mentioned problems and corrective measures including normalization of hip center and limb length discrepancy, need of mesh or antiprotrusio devices, evaluation for sciatic nerve injury and CT with 3D reconstruction (for columns and walls). Exposure of cup may be difficult due to tough fibrous tissue. Acetabular wall may be deficient or nonunited. Reduction may be difficult. Fitting of cup may be difficult. Metal cutting rasp to remove previous hardware may be required.

Fig. 4.3  Tuberculosis of left hip with wandering acetabulum (WA), resorption of femoral head and poor bone quality

Chapter 4  Radiographic Evaluation in Total Hip Arthroplasty

Femoral COnditions, Precautions and Problems Faced Old Surgically Treated or Conservatively Treated Fracture of Proximal part of Femur (Figs 4.5A and B) Calcar is absent. Upper part of femur is deformed. Vertical offset is reduced. Problems faced are removal of hardware, difficulty in making entry hole and judging the proper anteversion and difficulty in reduction. Think of using calcar replacement prosthesis and distal fitting stem (Solution); hardware removing rasp (Midas Rex), cutting less neck in femoral cut and taking care of greater trochanter to avoid intraoperative fracture in poor quality bone.

Limb Length (Fig. 4.6) Distance between two fixed bony points above the acetabulum and below on the proximal femur. Usually distance between a transverse line joining the lower most part of two ischial tuberosities (some people use transverse line joining the lower most part of two tear drops) and a transverse line joining the two lesser trochanter (mid or just above) is compared on both hips (in unilateral hip pathology) to calculate the shortening. Think of correct level of neck cut, proper use of head size (plus or minus), offset (127° or 132°) and restoring center of hip.

A

B Figs 4.4A and B  (A) Old neglected central fracture dislocation with poor bone quality; (B) Postoperative X-ray

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Section 1  Hip Arthroplasty

A

B Figs 4.5A and B  (A) Head in varus with resorption of calcar; (B) Postoperative X-ray (Solution stem)

Fig. 4.6  Limb length discrepancy (left side lesser trochanter is at the level of left tear drop). Also, note the poor bone quality

Chapter 4  Radiographic Evaluation in Total Hip Arthroplasty

Bowing of Femur Best seen in lateral radiograph. Mild: careful reaming and component impaction; Severe: may require osteotomy.

Center of Hip Horizontal and Vertical Offset Neck Shaft Angle Whether normal 130°, coxa vara (may have short limb); or coxa valga (may have long limb). Think of restoration of leg length and proper hip center. Use proper offset femoral stem.

Anteversion Normal is 10 to 15°. Difficult to measure on plain radiographs (need CT); increased anteversion (risk of anterior dislocation)/decreased anteversion (risk of posterior dislocation). Keep combined antiversion from 30 to 40° (about 20° acetabulum and 10° femoral stem). In posterior approach never reduce combined anteversion. Instead, it is safer to increased combined anteversion by 5 to 10°.

Fig. 4.7  Acetabular templating

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Section 1  Hip Arthroplasty

Templating for Prosthesis Determine the center of head, offset (vertical and horizontal), limb length discrepancy, size and position of femoral component, cup (size, position and cement mantle). Cup (Fig. 4.7): Center of acetabulum is marked through the template over radiograph (corrected for magnification) and it should correspond to the new center of rotation of hip. The template cup is placed at a 45° angle to the inter tear drop axis and is positioned with its medial part at tear drop, superior edge at superolateral acetabular margin, inferior edge at obturator foramen and it should overlap the minimal subchondral bone of cup. Center of acetabulum marked through the template corresponds to the new center of rotation of hip. Femur (Figs 4.7 and 4.8): Keep tip of neck of template stem at level of tip of greater trochanter and body of stem within the endosteal dimensions of the femoral diaphysis and metaphysis in both anteroposterior and lateral radiograph of hip with thigh. Diaphyseal measurements are scaled for magnification, decreasing the likelihood of undersizing or oversizing the femoral component.

CT Scan Indications of CT scan include dysplastic hip, old fracture dislocation of acetabulum, sequele of septic arthritis. Assess the configuration of acetabulum (walls, column, medial bone of acetabulum) and proximal femur (antevesion, deformity, dysplasia).

Fig. 4.8  Templating for femoral stem; 1. level of greater trochanter; 2. matching the medial inner cortex; 3. matching the lateral inner cortex; 4. at the center of femoral head.

Chapter 4  Radiographic Evaluation in Total Hip Arthroplasty

Magnetic resonance imaging To rule out infection in some cases.

Bone scan To rule out infection.

how to read postoperative x-ray? X-ray of pelvis with both hips anteroposterior view and hip joint with thigh lateral view is required.

Acetabular Component (Figs 4.9 to 4.11) Look for cup position (anteroinferior edge should be above and lateral to the tear drop, no space behind the cup if impacted till it touches the floor, medialization or lateralization), abduction angle (horizontal cup if: < 35°: vertical cup if: > 50°), screw position, size of cup (over or under size), status of bone graft (osteopenia, bone loss, DDH) and cavities (well filled with grafts or still prominent), cement mantle (at least 3 mm).

Fig. 4.9  Postoperative AP view after bilateral THR with good cup abduction (around 40 degrees), ITL (Inter-tear drop line), equalized limb length (LL) and well placed screws

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Section 1  Hip Arthroplasty

Fig. 4.10 Lateral view of the hip with well centered stem and cup (without any gap between cup and acetabulum)

Fig. 4.12  Varus placement of stem leading to lateral cortical perforation and extramedullary cement extravasation

Fig. 4.11  Vertical cup with high abduction angle

Fig. 4.13 Wiring around the diaphysis. Minimal calcar with diaphyseal fit using fully coated long stem prosthesis

Chapter 4  Radiographic Evaluation in Total Hip Arthroplasty

Fig. 4.14  Valgus stem

Fig. 4.16  Aseptic loosening of the acetabular and femoral components

Fig. 4.15  Varus stem

Fig. 4.17  Well fixed cemented femoral stem (5 years follow-up)

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Section 1  Hip Arthroplasty

Femoral Component (Figs 4.10 to 4.15) Look for size of head, center of rotation of head, offset, length of calcar, limb length discrepancy, varus or valgus position of stem, part of prosthesis above the neck (up to 1 cm acceptable without significant limb length discrepancy), cement mantle (4 mm proximal and 2 mm distal), any TBW for trochanteric fracture. Lateral view (Fig. 4.11): Look for intramedullary central position of stem, anteversion of femur, graft and cysts.

Follow-up Radiographs (Figs 4.16 to 4.19) Look for osteoingration of cup (absence of radiolucent lines between cup and parent bone, presence of superolateral and inferomedial buttress, medial stress-shielding, radial trabeculae), change in position, aseptic loosening, subsidence of stem and changing position of tip of stem.

Aseptic Loosening of Cup (Table 4.1) Definite Migration Horizontal or vertical migration >2 or 3 mm, change in opening angle of >5°.

Fig. 4.18  Septic loosening of the cemented hip stem

Fig. 4.19  Dislocation of femoral head

Chapter 4  Radiographic Evaluation in Total Hip Arthroplasty Table 4.1  Comparison of septic and aseptic loosening of joint prosthesis Parameter

Septic loosening

Aseptic loosening

Defining the problem

Loosening from joint infection is referred to as septic failure

Loosening from other (noninfectious reasons) such as bone fracture, brittle bones that cannot hold the implant, or some other mechanical problem like osteolysis is aseptic (without infection)

Pain

More

Less

Inflammatory markers- CRP, ESR

More elevated (CRP>10mg/L; ESR>30mm/hr)

Less elevated

Cytokine levels in synovial fluid

More elevated

Less elevated

Radiograph

Osteitis

Osteolysis

Histology- PMN infiltrates

≥ 5/hpf (97.8%)

≤ 5/hpf (99%)

Microbiology

Culture positive (89%)

Culture negative

FDG-PET scan

82.8% sensitivity; 87.3% specificity in septic loosening

Treatment options

•  Systemic antibiotics with or without surgical irrigation may be the first line of treatment •  Implant removal may be required

•  Loosening from bone fracture around the implant or fracture of the implant itself may require surgery •  Failed implant may need revision

Hypersensitivity

—

Hypersensitivity may lead to early loosening

Septic revisions

Suboptimal results

Better results

Probable Loosening Presence of a radiolucent zone at the cement-bone interface around the periphery of the entire component on at least one radiograph, extending for more than 50% of the stem circumference.

Possible Loosening Presence of a radiolucent zone at the cement-bone interface extending for more than 50% but less than 100% of the periphery of the component, and less than 50% of the stem circumference.

Other Criteria for Radiolucency Radiolucent lines appearing after 2 years and progressing in all 3 zones (≥ 2 mm in any zone). Causes may be graft related (migration, incorporation or resorption),

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Section 1  Hip Arthroplasty

Fig. 4.20  Assessment of acetabular cup positioning

polyethylene wear (decreased distance from head margin to articular margin at any point), instability (subluxation/dislocation).

Femoral Component (Fig. 4.20) Look for aseptic loosening, radiolucency, stem migration (compare the position of shoulder of prosthesis), varus/valgus, offset, center of head, limb length discrepancy, periprosthetic fracture, cement loosening, broken implant and dislocation. Increasing migration on serial X-rays is suggestive of stem failure.

5

chapter

Surgical Approaches and Indications of Hip Arthroplasty Conventional Surgical approach zz zz zz

Posterior approach Anterior or anterolateral approach. Mini or minimal invasive approach

Posterior Approach Check the correct side for surgery and position the patient in lateral and stable position with affected side up after induction of anesthesia. Use posterior support over sacrum avoiding any obstruction to hip movement. Patient should be in strict lateral position including the shoulder of affected side (Figs 5.1A and B). Drape the limb (Fig. 5.2).

A Fig. 5.1A  Lateral position with anterior support

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Section 1  Hip Arthroplasty

B Fig. 5.1B  Lateral position with posterior support

Fig. 5.2  The draped limb

Flex the affected hip up to 45° and give a straight skin incision (9-10 cm) starting 5-6 cm proximal to tip of greater trochanter extending through the tip and down along the shaft of femur (Fig. 5.3).

Chapter 5  Surgical Approaches and Indications...

Fig. 5.3 Incision with knee flexed at 45°, centered over the tip of the greater trochanter (TGT; Curved line) extending down over the lateral shaft of femur and proximally with slight curve posteriorly

Divide subcutaneous tissue and deep fascia along the line of incision down up to gluteus maximus. Lift the tendinous (Fig. 5.4) distal part of maximus and cut by cautery or knife and proximally by blunt dissection (Fig. 5.5). This exposes the

Fig. 5.4  Raising the lower part of the tendinous part of the gluteus maximus and separating the muscular part

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Section 1  Hip Arthroplasty

Fig. 5.5  The exposed part of the trochanter after blunt separation of the muscular part proximal to the tendinous portion of the gluteus maximus

Fig. 5.6  Trochanteric bursa after retracting the separated gluteus maximus with Charnley retractor

Chapter 5  Surgical Approaches and Indications...

Fig. 5.7  Cutting the trochanteric bursa to expose the external rotators and quadratus femoris muscle

trochanteric bursa (Fig. 5.6) which is incised transversely (Fig. 5.7) over the posterior border of greater trochanter and dissected down by pressing with a sponge in hand to expose the short external rotators and quadratus femoris (Fig. 5.8). At this stage sciatic nerve can be felt or seen with fat on the posterior aspect of quadratus femoris (Fig. 5.8). A Hohman retractor is passed below the abductors just above the tip of greater trochanter and piriformis tendon with few fibers of gluteus minimus

Fig. 5.8  Tip of trochanter (TP), piriformis tendon (P), superior gemellus (SG), obturator internus (OI), inferior gemellus (IG), quadratus femoris (QF) and sciatic nerve (SN)

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Section 1  Hip Arthroplasty

Fig. 5.9  Stay suture applied over the piriformis tendon, superior gemellus, obturator internus, inferior gemellus and part of quadratus femoris

Fig. 5.10 Raising a capsulomuscular sleeve with cautery starting from the attachment of external rotator with the trochanter and proximally extending it into the capsule over the middle of the head of femur

Chapter 5  Surgical Approaches and Indications...

Fig. 5.11  Already raised capsulomuscular sleeve and showing the exposed head

adherent to posterior capsule over exposed head (Fig. 5.8). Two to three stay sutures are applied in the piriformis tendon, short external rotators and proximal part of quadratus muscle (Fig. 5.9). Raise a conjoint-myocapsular sleeve (Figs 5.10 and 5.11) by starting cutting (with cautery) linearly over the capsule to piriformis tendon, short external rotators and part of quadratus. If patient has flexion deformity extend the dissection up to iliopsoas tendon attached to lesser trochanter; and tranverse and longitudinal fibers of gluteus maximus attached to posterolateral aspect of proximal femur. Dislocate hip by flexion, adduction and internal rotation of hip.

Anterior Approach It is in existence since last 40 yrs. It provides adequate and safe exposure to the hip. Low hip dislocation rate is a major advantage. It does not require any special table/ instruments (Table 5.1). The patient is placed in a supine (more common) or, if desired, a lateral position on the operating table. A straight lateral incision is made, and dissection is done up to fascia lata. The interval between the vastus lateralis and abductors is developed. The abductors can be released and repaired later. The hip capsule is identified and opened, and the hip is dislocated by traction and external rotation. The femoral head is then removed, allowing direct access to the acetabulum. The femur is placed into a figure-of-four position for broaching. Few patients can have a limp which lasts for 3-4 weeks due to abductor retraction. Limb length equality is better appreciated with stable hip.

Mini or Minimal Invasive Approach It adds to other existing controversial issues in total joint replacement. Following advantages and disadvantages of MIS have been described in the literature (Table 5.2).

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Section 1  Hip Arthroplasty Table 5.1  Approaches to THR Anterior/Anterolateral approach* Posterior approach Patient positioning

Lateral or supine

Lateral

Incision

Lateral

Postero-lateral

Abductor dysfunction More muscle damaging (Main disadvantage)

Less muscle damaging (Abductor sparing)

Dislocation

Less chance of dislocation (Main advantage)

More chances of posterior dislocation (Main disadvantage)

Limp

More common

Less common

Familiarity

Currently less common

More common

Myocapsular repair

Less important

Very important

Revision surgery

Posterior approach preferred

Can be done through Same approach

Cosmesis

Less

More

Bilateral Thr

Does not need change of position if supine

Needs change of position for the other hip

*Both anterior/anterolateral and posterior surgical approaches have strong advocates, and the choice of approach is best left to the surgeon.

Table 5.2  Advantages and disadvantages of minimal invasive surgeries Advantages1–3

Disadvantages

•  More of theoretical value except cosmesis •  Decreased tissue damage •  Decreased blood loss •  Less postoperative pain •  Faster postoperative recovery •  Shortened length of stay •  Improved cosmetic results

Problems •  Technically demanding •  Need special instrumentation and image assistance •  Poor visualization •  Difficulty in assessing the implant positioning and stability •  Tissue damage may be more than the conventional long incision Results4 •  Malpositioned components •  Instability •  Dislocation

Chapter 5  Surgical Approaches and Indications...

Indications for THR Total hip arthroplasty is usually indicated in osteoarthritis (trauma, septic or tubercular arthritis, avascular necrosis of hip, Perthes, DDH), and inflammatory arthritis (rheumatoid, ankylosing spondylitis, seronegative disease or psoriatic arthritis): zz Progressive original joint pathology despite conservative measures zz Pain and limitations of function affecting quality of life zz Rest or night pain zz Stiff hips zz Severe unacceptable deformity.

Absolute Contraindications Recent or current hip or distant infection, medically unfit patient.

Relative Contraindications Deficient or absent abductors function Neuropathic joint zz Progressive neurological disease. zz zz

References 1. Berger RA. Total hip arthroplasty using the minimally invasive two-incision approach. Clin Orthop Relat Res 2003;417:232-41. 2. Matta JM, Shahrdar C, Ferguson T. Single-incision anterior approach for total hip arthroplasty on an orthopaedic table. Clin Orthop Relat Res 2005;441:115-24. 3. Wright JM, Crockett HC, Delgado S, et al. Mini incision for total hip arthroplasty: a prospective, controlled investigation with 5-year follow-up evaluation. J Arthroplasty 2004; 19(5):538-45. 4. Woolson ST, Mow CS, Syquia JF, et al. Comparison of primary total hip replacements performed with a standard incision or a mini-incision. J Bone Joint Surg Am 2004; 86(7):1353-8.

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chapter

Perioperative Management of Total Hip Arthroplasty Preoperative clinical evaluation Assess the hip pain: It is usually in the groin, sometimes referred to anterior thigh or knee, is increased by activity or weight-bearing and may be partially relieved by rest or restricted weight-bearing. Pain in the buttock or lower posterior pelvis may be from lumbosacral spine, sacroiliac joint or sacrum. Assess the patients expectation, occupation and discuss the needed lifestyle modification after hip arthroplasty. Assess the range of motion, deformity, adductor contracture and limb length discrepancy. Look for movements and deformities of affected knee and spinal deformity. Abductor strength: Trendelenburg’s test. Stop aspirin/disprin 7-10 days before surgery. Stop oral anticoagulants 48 hours before surgery. Start insulin for uncontrolled diabetes/omit morning dose of oral hypoglycemic on the day of surgery for NIDDM(Type 2 DM). Control hypertension, Stopping of anti-rheumatoid drugs before surgery is controversial (some suggest to stop it as it increases the risk of wound problems/infection; others say to continue: as it will reduce the postoperative pain and activity of disease by reducing the inflammation). Rule out hip infection by (ESR, CRP, TLC, bone scan, MRI) or treat infection before surgery (Normal ESR, CRP, Bone scan and TLC). Informed and written consent for surgery (explain alternative treatment, advantages/ disadvantages, result of THR; do not give assurance of absolute equal limb length). One dose of intravenous antibiotics (cefotaxime/ceftriaxone) in the morning or one hour before starting the surgery. Avoid aminoglycosides (gentamycin, amikacin) in renal disease.

Chapter 6  Perioperative Management of Total Hip Arthroplasty

Bilateral THR in one sitting: Medically fit patient with bilateral severe arthritis of joints, or stiff hip/flexion deformity for better rehabilitation.

Postoperative Clinical Management Shifting of patient to bed or trolley: Both lower limbs should be in abducted and externally rotated position with a pillow (Charnley pillow) between legs (Fig. 6.1). While shifting from operation table to trolley or bed, adduction and internal rotation should be avoided to prevent dislocation. One person should focus on the hip area and other on holding lower limbs in abduction and external rotation. Immediate postoperative care: Check for vital sign, soakage of dressing (do suprabandaging), pulse, BP, respiratory rate, O2 saturation; blood in suction drain (one ring is roughly around 100 ml) and replace accordingly; distal pulses (dorsalis pedis and posterior tibial artery); color (should be pink) and capillary refill (normally 25 mm may be used). Posteriorinferior quadrant has inferior gluteal and internal pudendal neurovascular structures (length should be < 25 mm). Anterosuperior quadrant have external iliac artery and vein while anteroinferior quadrant have obturator neurovascular bundle (length < 20 mm in anterior quadrant). Avoid prominence of screw head to prevent back wear of polyethylene liner. Liner (Fig. 7.23): Edges of the cup should be free from osteophytes and soft tissues for proper placement of liner. Hood (elevation) of polyethylene liner should be kept posterosuperiorly or superiorly (if abduction is more). Proper placement should be checked by attempting the extraction of liner with extractor. Femoral stem: Insert the definitive stem (with same precautions for anteversion and prevention of varus position) initially by manual pushing then with hammer (take same care as while with broach) up to the desired length. If its proximal part does not go up to the desired point: hand reamer or flexible reamer should be passed to remove any distal bone followed by removal of proximal bone by curette, or small thin osteotome. Mostly stem sinks after proximal and distal bone removal, if it remains few mm protruded from the canal: can be left and head size adjusted accordingly (trial with one size small head).

Chapter 7  Primary Total Hip Arthroplasty

Fig. 7.23  Definitive liner in situ

Fig. 7.24  Passing of the sutures through greater trochanter for rotator repair

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Fig. 7.25  Completed rotator repair

Attach trial head and again check ROM, stability, limb length. Then insert definitive head and reduce the hip. Again check ROM, instability, limb length and abductor tightness.

Wound closure Reattach the piriformis tendon, external rotators and part of quadratus femoris by passing the sutures (surgeon’s preference: Non-absorbable monoacryl/ethibond (number 2 or 5) sutures through posterolateral aspect of greater trochanter and muscles with limb in position of abduction and external rotation (Figs 7.24 and 7.25). Reattach the distal part of gluteus maximus (longitudinal, if possible transverse fibers also), suture tendinous part of gluteus maximus with monoacryl/ethibond (cross horizontal mattress suture) and proximally with vicryl. Close deep fascia with vicryl, and subcutaneous tissue (if excessive subcutaneous fat: close fat in two layers) with vicryl. Skin is closed by staple or monocryl and may be left if subcuticular sutures have been applied. Postoperative skin traction: May be applied for mild residual flexion (10-15°) deformity of hip for 3-5 days.

Reference 1. Wasielewski RC, Cooperstein LA, Kruger MP, et al. Acetabular anatomy and the tranacetabular fixation of screws in total hip arthroplasty. BJS 1990;72 A:501.

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chapter

Complex Primary Total Hip Replacement

Primary total hip arthroplasty may be difficult and requires experience in certain primary pathologies like protrusio, dysplastic or ankylosed hips and in the presence of an implant in situ for proximal hip or acetabular fractures.

total hip replacement in Protrusio Hip Problems Medial migration of the hip center Superior and medial migration of the head making acetabulum—oblong zz Difficult dislocation zz Risk of spiral fracture of femur while dislocating the femoral head zz Deficient medial support for cup zz Shortening of the affected limb zz Sciatic nerve: Close to the joint. zz zz

Tips and Tricks for THR A good preoperative templating for limb length inequality Either dislocate the hip by extra soft tissue release and excision of posterior osteophytes. If not possible then do in situ neck osteotomy zz Lateralization of acetabular cup (Figs 8.1 and 8.2) with medial bone grafting (morcellized cancellous) zz Careful reaming to create convergence of the acetabular rim without preferentially reaming the superior rim and causing an iatrogenic superior segmental defect or high hip center. zz Never ream/deepen the medial wall zz Peripheral reaming to obtain a good peripheral fit. zz zz

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Fig. 8.1  Left side protrusio hip

Fig. 8.2  The well-incorporated medial bone graft after THR

Chapter 8  Complex Primary Total Hip Replacement

Total Hip Replacement in Ankylosed hip Problems Faber (Flexion, abduction and external rotation) deformity is not uncommon. Exposure is very difficult in these deformities. zz These hips are difficult to dislocate (Figs 8.3 and 8.4A and B). zz Require in situ provisional neck cut followed by reaming of the in situ head till acetabular surface becomes visible then do definitive neck osteotomy (Fig. 8.5). zz Cementless hips may be the best option for these young active patients zz These patients tend to have external rotation deformity and increased anteversion of the femur. zz Bone is osteoporotic due to disuse so acetabular over-reaming should be avoided and leaving a spike of bone at the superolateral acetabular margin may support cementless cup1. zz Patients tend to have anterior instability or dislocation due to various reasons including hyperextension1 at the hip predisposing a more anteverted and more vertical inclination of the acetabular cup, external rotation and increased femoral anteversion causing impingement of the prosthetic neck or the greater trochanter posteriorly or difficulties in the placement and/or reduction of the hip.2 zz High rate of heterotopic ossification. zz

Fig. 8.3  FABER deformity

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A Fig. 8.4A  A case of bilateral ankylosed hip

B Fig. 8.4B  Postoperative radiograph after bilateral total hip arthroplasty

Chapter 8  Complex Primary Total Hip Replacement

Fig. 8.5  Definitive osteotomy of neck

Tips and Tricks for THR For neck resection, approach the inferior neck and feel the lesser trochanter and pubo-femoral arch. Osteotomy of neck may require two stages. zz In situ provisional neck osteotomy is performed (Avoid cutting into greater trochanter, calcar and posterior acetabular wall). Then finally do definitive osteotomy. zz Leave the superolateral acetabulum bone spike during reaming which will provide support to cementless cup and avoid tendency of vertical inclination of the cup. zz Remove the remaining femoral head piecemeal. zz Ream medially with sequential reamers till foveal soft tissue which defines original joint plane. Avoid over reaming of anterior and posterior wall. Use of small cups is advisable. zz Soft tissue release: For flexion deformity release anterior and superior capsule, iliopsoas and rectus femoris (if needed). zz For severe deformities (Consider two stage surgery or two incision techniques): Anterior approach for image guided osteotomy of neck in supine position, followed by usual posterior approach. zz Trochanteric osteotomy or slide may be required but should not be routinely done. zz Postoperatively indomethacin for 2 weeks to prevent heterotopic ossification.

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Dysplastic Hip Problems Dysplastic acetabulum with sloping walls (Fig. 8.6). Usually anterolateral and superior bone are deficient zz Difficult acetabulum exposure due to severe soft tissue contractures and prior childhood pelvic osteotomies zz Up ridden trochanter (high dislocations), increased neck shaft angle and increased femoral anteversion zz Proximal femur may have a narrow canal or may be distorted due to prior femoral osteotomies zz Adductor contracture. zz zz

Tips and Tricks for THR Aim should be to place the cup in true acetabulum having maximum bone stocks with anatomic hip center zz Usually a small size cup should be used zz Start with the smallest size reamer and do not over ream the lateral most acetabulum wall zz Bone graft: If coverage is > 70%: No graft is required. If uncoverage of head is > 30%: Use contoured femoral autograft fixed with lag screw (Figs 8.7 to 8.9). zz

Fig. 8.6  The dysplastic hip with deficient posterosuperior acetabular wall

Chapter 8  Complex Primary Total Hip Replacement

Fig. 8.7  A provisional fixation of the bone graft prepared from head with K wires

Fig. 8.8  A definitive fixation of the bone graft prepared from head with screws

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Fig. 8.9  Postoperative radiograph of hip arthroplasty

If uncoverage is > 45 %: Use cemented cup with femoral head supported with a auto/allograft zz Femur: Good soft tissue release- anterior capsule, iliopsoas, gluteus maximus and even rectus femoris muscle in some cases for flexion deformity or to bring down the femur after neck osteotomy. zz Use specially designed short/low offset CDH stem zz In high dislocation: Subtrochanteric femoral shortening may be required zz Modular or cemented stem should be used for extreme anteversion.

References 1. Kilgus DJ, Namba RS, Gorek JE, et al. Total hip replacement for patients who have ankylosing spondylitis: the importance of formation of heterotopic bone and of the durability of fixation of cemented components. J Bone Joint Surg Am 1990;72:834. 2. Tang WM, Chiu KY. Primary total hip arthroplasty in patients with ankylosing spondylitis. J Arthroplasty 2000;15:52.

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chapter

Complications of Total Hip Arthroplasty

Hematoma Formation It is commonly seen due to injury to first perforating branch of the profunda femoris artery deep to the gluteus maximus insertion (during release for flexion deformity) or to branches of the obturator artery (when osteophytes are removed from inferior acetabular margin or incision is made to release hypertrophic transverse ligament obstructing the cup vision). Prevention is by adequate homeostasis with closed suction drain (controversial) and treatment includes correction of the predisposing factors (coagulopathy, drugs), compression dressing and occasionally by surgical drainage (for wound gaping or necrosis, infection, compartment syndrome) and use of closed suction drain.

Mortality In hospital mortality: 0.16 to 0.52%. At 90 days: Primary total hip arthroplasty-1% and 2.5% for revision hip.

Heterotopic Ossification (Fig. 9.1) It occurs in up to 10% of cases. It is more common in post-traumatic secondary osteoarthritis (hypertrophic osteophytes) and in patients with previous history of heterotopic ossification. It is also seen in cases of ankylosing spondylitis, diffuse idiopathic skeletal hyperostosis, Paget disease, and unilateral hypertrophic osteoarthritis. Common site is area of adductors and iliopsoas muscles in the form of calcification around 3-4 weeks after surgery and treatment includes NSAID (Indomethacin) or low dose (500 cGy) radiotherapy (Preoperative and postoperative).

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Section 1  Hip Arthroplasty

Fig. 9.1  Heterotopic ossification in a case of THR

Thromboembolism The risk of fatal PE (Pulmonary embolism) following primary hip or knee replacement has been consistently reported to be between 0.1 and 0.2%, regardless of the chemoprophylactic agent employed for prophylaxis.1,2 Better postoperative care, pain management and early mobilization has reduced the incidence of thromboembolic phenomenon drastically.

Nerve Injury Primary THR: 0.7 to 3.5%. Revision THR: 3.2 to 7.5 %. Sciatic nerve may be injured during exposure (nerve is close in protrusion, revision, DDH, external rotation deformity, resorption of head and neck, due to vigorous retraction of soft tissue on the posterior aspect of acetabulum, due to cement, subgluteal hematoma or excessive lengthening (> 4 cm). Incomplete recovery is very

Chapter 9  Complications of Total Hip Arthroplasty

common and complete recovery is seen only in few patients. Give patient foot drop splint to prevent equinus of foot. Femoral nerve may be injured by retractors placed anterior to the iliopsoas, during excision of anterior capsule or femoral retraction for acetabular preparation. Complete recovery is quite common and patient should be given knee immobilizer/support till nerve recovery. Obturator nerve may get injured due to screw in the anteroinferior quadrant, extruded cement or by retractors.

Vascular injury These are very rare (0.2% to 0.3%) and are usually seen in revision surgery (due to direct injury by screw, cement, cage or due to retractor placed anterior to iliopsoas).

Limb Length Discrepancy Patient are more worried for lengthening (particularly for unilateral hip disease) than shortening. Lengthening up to 1 cm is well tolerated but excessive lengthening may cause limping or sciatic nerve injury (> 2.5-4 cm). Preoperative templating in association with intraoperative measurement is the most accurate method for equalizing limb length.

Instability (Dislocation and Subluxation) Risk of dislocation after primary arthroplasty is about 2-5%.3 More than half of all dislocations occur within the first three months after surgery and more than three quarters within one year.4 Factors predisposing to instability include malpositioned components (excessive ante or retroversion, inadequate offset or center of head), inadequate soft tissue tension, abductor insufficiency, impingement (extreme movements of flexion, internal rotation) of neck of femoral component and femur over cup margin or femur on pelvis (or osteophytes), trauma, extreme position of limbs, posterior approach, revision surgery, trauma and small size of head. Posterior dislocation usually occurs due to decreased anteversion (by flexion, adduction, internal rotation of hip) and anterior dislocation occurs due to increased anteversion (by flexion, abduction and external rotation) of components. Anterior dislocations are very uncommon in posterior approach. Diagnosis is on the basis of attitude of limbs and radiographs (AP and lateral). Treatment is to evaluate the cause and closed reduction (traction with hip and knee at 90° with downward counter traction on pelvis assisted by mild abduction of thigh or by Allis or Stimson method) under sedation or GA. If closed reduction (due to soft tissue interposition, displaced liner, lax soft tissue or unstable reduction) fails; plan for open reduction with preparation for possible replacement of culprit components (liner/head/cup/femur). Recurrent dislocation usually occurs due to malposition of the components, abductor insufficiency or lax soft tissues and is better managed by revision surgery.

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References 1. Douketis JD, Eikelboom JW, Quinlan DJ, et al. Short-duration prophylaxis against venous thromboembolism after total hip or knee replacement: a meta-analysis of prospective studies investigating symptomatic outcomes. Arch Intern Med 2002; 162(13):1465-71. 2. Brookenthal KR, Freedman KB, Lotke PA, et al. A meta-analysis of thromboembolic prophylaxis in total knee arthroplasty. J Arthroplasty 2001;13(3):293-300. 3. Mahoney CR, Pellicci PM. Complications in primary total hip arthroplasty: avoidance and management of dislocations. Instr Course Lect 2003;52:247-55. 4. Woo RY, Morrey BF. Dislocations after total hip arthroplasty. J Bone Joint Surg Am 1982; 64:1295-1306.

Section

2

Knee Arthroplasty

10

chapter

Applied Anatomy of Knee Joint

Knee joint Largest synovial joint of the body.

Parts of the Joint Distal end of femur, proximal tibia and articular surface of patella (Figs 10.1A and B). Menisci: There are two menisci. Medial one is attached at its periphery to the capsule and tibial collateral ligament. Lateral meniscus is attached to the tendon of the popliteus. Both the menisci are interconnected anteriorly by the transverse ligament (Fig. 10.2). Infrapatellar fat pad: It separates the synovial membrane from the patellar ligament. It has to be partially excised for eversion of the patella (Fig. 10.3). Ligamentum patellae: It is the continuation of quadriceps tendon below the patella (Fig. 10.4), it is attached above to the apex of patella and below to the tibial tuberosity. Care should be taken to prevent any injury to it during soft tissue release and eversion of patella. Lateral collateral ligament: It is attached above to the lateral epicondyle and below to the lateral surface of head of fibula. Medial collateral ligament (Fig. 10.5): It is attached above to the medial femoral epicondyle just distal to the adductor tubercle and below to the medial edge and medial surface of tibia above and behind the attachment of sartorius, gracilis and semitendinosus tendons. It should be protected with medial soft tissue sleeve while taking the femoral and tibial bone cuts. Anterior cruciate ligament: It is attached below to a facet on the anterior part of the intercondylar area of the tibia and above to a facet on the posterior aspect of the lateral wall of intercondylar notch of femur.

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Section 2  Knee Arthroplasty

A

B Figs 10.1A and B  The knee joint in AP and lateral view

Fig. 10.2  Photograph of meniscus, popliteus, cruciate ligaments

Chapter 10  Applied Anatomy of Knee Joint

Fig. 10.3  The exposed knee joint

Fig. 10.4  The quadriceps tendon, patella, ligamentum patellae

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Fig. 10.5  Medial collateral ligament (at the tip of artery forceps)

Fig. 10.6  The Q angle between the line through center of patella (CPO) and tibial tuberosity (TT) and line from center of patella to the anterior-superior iliac spine (ASIS)

Chapter 10  Applied Anatomy of Knee Joint

Posterior cruciate ligament: It is attached below to the posterior aspect of the intercondylar area of the tibia and above to the medial wall of the intercondylar notch of femur. Blood supply: It is supplied from the descending and genicular branches from femoral, popliteal and lateral circumflex femoral artery. Nerve supply: It is supplied by the branches from obturator, femoral, tibial and common peroneal nerve. Q angle: It is the angle (Fig. 10.6) between the extended anatomical axis of the femur and the line between the center of patella and the tibial tubercle. Large Q angle tends to cause lateral subluxation of patella.

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History and Biomechanics of Knee Arthroplasty

zz zz

zz zz

Fergusson (1861): Treated knee arthritis by resection arthroplasty. Campbell (1930): Established interposition knee arthroplasty (using free fascial grafts) in arthritic joints. Campbell and Boyd (1940) and Smith-Petersen (1942) performed mould arthroplasty. A Canadian orthopedist, Frank Gunston (1960-68), from Sir John Charnley’s Hip Center, developed and used the first metal on plastic knee replacement secured to the bone with cement.

Total condylar prosthesis (TCP) (Zimmer, Warsaw, IN): Insall introduced it in 1974. It was cemented cruciate sacrificing knee prosthesis with a relatively conforming tibiofemoral articulation. Stability depended on soft tissue balance in flexion and extension, along with moderate articular conformity in the coronal and sagittal planes. But it had problems like posterior subluxation of the tibia, decreased range of motion (90-100° flexion), poor stair climbing and impingement of posterior femoral metaphysis against tibial articular surface (at 95° of flexion). To solve these problems, new design (modified TCP), Insall Bernstein posterior stabilized prosthesis (IB-I) was introduced in 1978. It had femoral cam (to function as mechanical PCL) to articulate with a tibial spine as a substitute for the excised PCL. It had originally all polyethylene tibial components which were later fabricated with metal backing (1981). A new modular design, IB-II (1987) was introduced to accommodate modular tibial inserts, wedges, stems and augments. Further changes in this design by Insall led to two new designs, Legacy posterior stabilized knee prosthesis (LPS) (Zimmer, Warsaw, IN) and the LPS-Flex (it has both fixed and mobile bearing tibial component). Differences between normal and prosthetic joint are given in Table 11.1.

Chapter 11  History and Biomechanics of Knee Arthroplasty Table 11.1  Differences between normal joint vs prosthetic joint Normal joint

Prosthetic joint

Tibial articular surface

•  At 3° varus from the true vertical axis of body

•  At 90° to long axis of tibia •  10 mm tibia is cut to accommodate minimum thickness of tibial plate (10 mm) from the least affected tibial plateau •  Extramedullary rod in internal rotation leads to posterolateral slope and external rotation results in posteromedial slope

Distal femoral articular surface (valgus)

•  Distal femoral articular surface is in 9° valgus (anatomical axis 6° valgus to mechanical axis + tibia articular surface in 3° varus) in relation to tibia

• Since tibia is at 90° (not in 3° varus),  femoral valgus should be reduced to 6° (to achieve neutral mechanical axis) •  Distal femoral cut thickness should be equal to thickness of prosthesis

Distal femoral articular surface (rotation)

•  In flexion, articular surface (line) remains parallel to ground because of asymmetry of posterior femoral condyle in relation to varus tibial articular surface (medial condyle extends 2 mm more on the articular surface than lateral condyle)

•  At 90° tibial articular surface, lateral gap is more than medial •  For balancing this femur has to be cut in 3° external rotation in relation to posterior condylar axis (cut more thickness of medial than lateral in posterior cut)

Patella

•  Medialized, 12-15 mm of host patella should be left after resection for prosthesis

Femoral component

•  6° valgus, 3° external rotation, 90° to long axis of femur in sagittal plane and should be in the centre or lateralized

Biomechanics of normal joint and a prosthetic joint Anatomical axis of lower limb (Fig. 11.1): A line drawn along the long axis of femur extending down along the long axis of tibia. It forms 6° valgus angle with mechanical axis and forms 9° valgus angle from true vertical axis of body. Mechanical axis (Fig. 11.1): A line extending from the center of the femoral head to the center of the talar dome on a standing long leg anteroposterior radiograph. Neutral mechanical axis passes from center of femoral head to the center of ankle joint (center of tibial plafond and center of dome of talus) through center of knee joint (center of intercondylar notch and center of tibial plateau).

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Fig. 11.1  The mechanical axis (MA), vertical axis (VA) and femoral shaft axis (FSA)

Fig. 11.2 Change of instant center of rotation (ICR) in flexion from 0-120° forming J curve

Fig. 11.3  Femoral rollback on tibia with flexion

Chapter 11  History and Biomechanics of Knee Arthroplasty

Screw home mechanism: It is external rotation of tibia over femur during extension of knee (opposite occurs during flexion of knee). J curve (Fig. 11.2): Transverse axis of flexion and extension constantly changes and follows a J shaped curve around the femoral condyle. Femoral rollback (Fig. 11.3): With increasing flexion, femur rolls back over the tibial condyle.

Polyethylene Polyethylene liner in TKR usually comes in following three shapes: 1. Flat polyethylene surface: Flat articular surface gives areas of high contact stress due to less conforming articulation with femur in sagittal plane. 2. Polyethylene with a post: For cam mechanism and femoral rollback where PCL is sacrificed. 3. Polyethylene with dished surface: More conforming in coronal and sagittal planes.

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Implants and Patient Selection

Osteoarthritis of Knee joint It is most common in Indian female patients.

Clinical Features zz zz zz zz zz

Pain during movement, weight bearing, climbing stairs and after prolong sitting Deformity Crepitus Instability Stiffness.

Radiological Features Staging of Osteoarthritis (Fig. 12.1) of the Knee48 (Kellgren) Stage 0 No abnormality.

Stage 1 Incipient osteoarthritis, osteophytes on the eminences.

Stage 2 Moderate joint space narrowing, moderate subchondral scelerosis.

Stage 3 >50% joint space narrowing, rounded femoral condyle, extensive subchondral sclerosis, extensive osteophyte formation.

Chapter 12  Implants and Patient Selection

Fig. 12.1  Kellgren stages of osteoarthritis of knee

Stage 4 Joint destruction, obliterated joint space, subchondral cysts in the tibial and femoral condyle, joint subluxation.

Treatment Conservative It includes modification of life styles (avoid cross legged sitting, squatting, prolong climbing of stair and use of English toilet), analgesics (Non steroidal anti-inflammatory drugs, opioids), Physiotherapy (quadriceps exercise, local ultrasound, interferential therapy) and walking aids (crutches walking stick, shoe wedges), Diacerin, intra-articular steroid and hyaluronic acid injections.

Surgical49-51 Joint sparing options: Symptomatic: Arthroscopic lavage, shaving, debridement zz Bone-stimulating: Microfracture, drilling, abrasion arthroplasty zz Joint surface restoration: Autologous osteochondral transplantation (OCT), autologous chondrocyte transplantation (ACT) zz Corrective osteotomy near the joint: High tibial osteotomy. zz

Joint Replacements zz zz

Partial: Unicondylar knee arthroplasty, patellofemoral arthroplasty Total knee arthroplasty.

Ideal Patient for Total Knee Arthroplasty zz zz zz zz zz zz

Thin built Minimal comorbidities Moderately active Good range of motion Not too old Not too young.

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Indications of Total Knee Arthroplasty zz zz zz zz

Progressive original joint pathology despite conservative measures Pain and limitations of function affecting quality of life Rest or night pain Deformity and instability in arthritic joint.

Contraindications zz zz zz zz zz zz

Recent or current knee or distant infection Medically unfit patient Discontinuity or severe dysfunction of extensor mechanism Recurvatum due to muscle weakness Neuropathic arthropathy Morbid obesity.

Unilateral vs bilateral TKR: It remains controversial and literature is also divided. Different studies report the following advantages and disadvantages of the single stage bilateral TKR (Table 12.1).

Cruciate Retaining VS Cruciate Substituting (Fig. 12.2 and table 12.2) Three bias for posterior cruciate ligament among arthroplasty surgeons: Always preserve: Believe that it gives more range of motion and symmetrical gait (especially during stair climbing) due to better controlled femoral roll back.

Table 12.1  Comparison of bilateral and unilateral Tkr Bilateral

Unilateral

Indications

Young and elderly fit patients

Elderly patients, > 75 years

Advantages

•  Short hospital stay, better Less complications rehabilitation, less overall cost1,2 •  Better functional outcome and patient satisfaction score2,3

Disadvantages

• High incidence of confusion (usually due to lower hemoglobin levels and the systemic dissemination of fat emboli4–6, and transient hypoxia • Increased risk of DVT, pulmonary embolism, myocardial infarction in elderly patients2,5,7

High cost, delayed rehabilitation

Decision should be individualized for the patients and should take into consideration various factors (age, associated co-morbidities, experience of the surgeon, hospital set up) affecting the outcomes after TKR.

Chapter 12  Implants and Patient Selection

Fig. 12.2  NRG CS and CR design (Courtesy: Stryker)

Table 12.2  Comparison cruciate substituting and cruciate retaining designs Cruciate substituting

Cruciate retaining

Advantages

•  Less technically demanding •  More stable component interface8 •  Better range of motion9 because of smooth posterior roll back

•  Useful for young and active patient •  Preserves bone stock and proprioception •  More symmetrical gait (especially during climbing) •  Better stability (PCL prevents anterior translation of the femur on the tibia) All these claimed advantages10 have been disapproved in different studies and shows comparable results with CS design

Disadvantages

•  Tibial post polyethylene wear •  More bone resection (for post and cam mechanism)11 •  Risk of patellar clunk in deep flexion

•  Can be used only in patients with good bone stock. Healthy ligaments are required for optimum functional outcome •  Not a suitable implant for patients with severe varus,12 valgus or flexion deformity,11 rheumatoid arthritis, postpatellectomy, femoral/tibial osteotomy13,14 •  Early tight PCL: Loss of flexion or ligament rupture15 •  Late rupture (common in rheumatoid arthritis): Pain and flexion instability16

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Always substitute: Believe that PCL is already degenerated and does not perform its function adequately Intraoperative decision: Decide on the morphology of PCL. Results are controversial. Different outcomes following merits and demerits of each design have been reported in the literature. Implant choice should be guided by surgeon’s experience, training and pathology of PCL.

High Flex Design (Fig. 12.3) Deep flexion (High flexion): A flexion of 120° is called deep high flexion. It is required in Asian population for religious activities, for Indian toilet and professional activities (manual worker, farmer, plumbers). New high flex design: These designs have thick posterior femoral condyles with reduced radii (increases the contact area between the posterior condyles and the tibial insert in deep flexion) of posterior femoral condyles. They also have modified tibial and femoral components to improve extensor mechanism in deep flexion and posterior femoral rollback.17

Patient Selection for High Flex Design zz zz zz zz

Preoperative flexion should be 120° Demand of deep flexion activity Thigh-calf index should be more than 90% (Thigh and calf should be thin) Collaterals should be functional and stable.

Fig. 12.3  High flex design

Chapter 12  Implants and Patient Selection

Disadvantages of High Flex Designs Short radius: It has been shown to increase the polyethylene wear18 due to high contact stresses during terminal flexion. It may make revision surgery more difficult due to additional removal of bone from the notch area in cruciate substituting (CS) design and of 2-4 mm bone from the posterior condyles.19 High flexion: It may lead to increased stress on patellofemoral joint, pain, patellar fracture and loosening.

Results of High Flex Designs Results are controversial, some suggest no difference20 in flexion while others show variable range of flexion (Hy-Flex II21; >120°, NexGen LPSFlex:138°; NexGen1 LPS:135°).22

Fixed VS Mobile Knee (Fig. 12.4) Fixed bearing knees have shown an excellent survival rate of > 90% at 10–15 years after the operative procedure.23–25 Proponents of mobile knee say that long term results have been documented in a relatively older population (> 60 to 65 yrs), a better polyethylene and stable implant fixation is necessary for the younger patients and that can be provided by mobile bearing knees only. Literature is again conflicting showing comparable results, but there is no long-term follow-up for younger patients26,27 showing better results of one prosthesis over another. Following are described pros and cons of each design (Table 12.3). Mobile knee: Oxford, LCS, Scorpio Plus, MBK, PFC-Sigma RP, PFC- RPF, LPS Flex Mobile.

Gender Knees Zimmer knee: It has a modified ML/AP aspect ratio, decreased thickness of the anterior flange and increased trochlear groove angle in comparison to the original NexGen knee (Zimmer, Inc).33 Table 12.3  Comparison of fixed bearing and mobile bearing knee

Advantages

Fixed knees

Mobile knees

• Long-term survival23,24 • More stable

• Perhaps higher degree of tibiofemoral conformity • Lower contact stresses • Lower rotational constraint28

Disadvantages • Rotational constraint of some designs may lead to increased torque to insert-base-plate interface • Back-side wear29

•  Limited indications •  Back-side wear •  Fair possibility of insert subluxation or dislocation.30,31 •  Mechanical failure rate high (1-2%)32

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Section 2  Knee Arthroplasty

Fig. 12.4  Mobile knee design

Triathlon knee system (Stryker Orthopedics, Mahwah, NJ): The femoral component is narrowed in the ML dimension, and the 8 sizes grow by no more than 3 mm in the AP dimension. The addition of a 7° anterior flange angle was designed to minimize the risk of notching the anterior cortex, especially if downsizing is necessary.33

Cemented vs Noncemented Results are controversial. Some studies report that there are no differences in the long-term result of cementless and cemented TKR.34-36 While others report the advantages and disadvantages of each procedure.

Cementless TKR Advantages zz zz zz

Avoids toxic effects of cement on the body37 Preserves sufficient bone stock for revision38 Allow early treatment of postoperative infection.38

Disadvantages • Weak early fixation Radiolucent lines below the tibial plate (showing absence of bony ingrowth)38 (Tibial tray loosening).

zz

Chapter 12  Implants and Patient Selection

Cemented TKR Advantages39 Documented long-term survival It can interdigitate into both soft and hard bone zz It can adjust minimal improper bone cuts Now new designs have less osteolysis due to modular tibial tray with improved locking mechanism, more wear resistant polyethylene with less abrasive surface. zz zz

.

Disadvantages zz zz

Revision can be difficult due to cement fixation Theoretically cement complications like emboli can occur.

All POLYETHYLENE VS Metal Backed tibia40,41 Results are controversial. Use minimal thickness >10 mm. One recent study in Chinese40 population found no significant difference between the two groups (All polyethylene and metal backed implant with respect to HSS scores, ROM, clinical and radiographic parameters measured and survival rate) Table 12.4.

Table 12.4  Comparison of metal back tibia and all polyethylene tibia Metal backed tibia40,41 Advantages

All polyethylene tibia40,41

• Liner can be adjusted after • Less expensive insertion of trial or final • No problem of separate polyethylene prosthesis and can be changed liner (back-side wear, dissociation) during revision surgery • It allows good prosthesisprimary bone contact interface with additional modular augment or stem for bone loss • Documented excellent survival

Disadvantages • Either more proximal tibial •  Once inserted then no further bone is resected or less adjustment can be done thickness of polyethylene may •  Whole component has to be be used to restore the stability removed for revision surgery • Liner dissociation or dislocation •  Not suitable for soft bone in rotating platform • Expensive

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Section 2  Knee Arthroplasty Table 12.5  Comparison of various anticoagulation prophylaxis strategies Routine prophylaxis

Judicious prophylaxis

•  Reduces the incidence of DVT •  Probably reduces the incidence of pulmonary embolism

•  Wound complications and bleeding related complications can be avoided •  Cost effective

Disadvantages •  Expensive therapy •  Wound hematoma, increased blood loss in drain, delayed wound healing, skin staining/ discoloration (Figs 12.5 and 12.6) •  Probably does not alter the incidence of fatal pulmonary embolism

•  Asymptomatic DVT may become symptomatic and may lead to pulmonary embolism very very rarely •  Epidural/intracranial bleed

Advantages

Fig. 12.5  Skin staining/discoloration due to low molecular weight heparin

Routine vs Judicious Use of Anticoagulant Prophylaxis Routine use of anticoagulant chemoprophylaxis has been questioned lately in few published studies. Following advantages and disadvantages of routine and judicious of anticoagulant chemoprophylaxis have been described in the literature (Table 12.5).

Chapter 12  Implants and Patient Selection

Fig. 12.6  Skin necrosis and infection due to low molecular weight heparin

Patellar Resurfacing Controversial, may be done in following situations: Extensive patellofemoral osteoarthritis with predominantly anterior knee pain zz Preferable in rheumatoid arthritis zz History of patellar subluxation/dislocation zz Intraoperative patellar maltracking or extensive patellar cartilage loss. zz

Complications of patellar resurfacing: It includes improper size, maltracking, loosening, fracture and osteonecrosis of patella. If you do not resurface, ensure three things: Excellent patelloplasty zz Circumcision with cautery zz Ensure good patello-femoral tracking. zz

Unicondylar Knee Prosthesis (Fig. 12.7) One Finger Test (Bert 2005) Patient should point towards a single compartment of the knee joint when asked for site of pain. Table 12.6 describes unicondylar knee indications and pros and cons.

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Fig. 12.7  Unicondylar prosthesis in situ

Fig. 12.8  Constrained prosthesis

Chapter 12  Implants and Patient Selection Table 12.6  Unicondylar knee-indications, advantages and disadvantages Indications42

Advantages42-44

Disadvantages42,45,46

• Nonobese patient with sedentary lifestyle • Unicompartmental osteoarthritis or post-traumatic arthritis • Varus deformity < 10° • Minimum 90° flexion without flexion deformity

• Less bone is removed for implantation of the prosthesis • Reduced blood loss • Improved range of motion • Reduced hospital stay • Reduced cost of treatment • Biomechanics is closer to the normal knee

• Poor instrumentation and design • More technically demanding • Poor fixation • Reduced prosthesis survival than TKR prosthesiss • Development of osteoarthritis in the other compartment

Contraindication42-47

Complications42

• Rheumatoid arthritis • More chances of failed • Patients with nonlocalized prosthesis due to various knee pain reasons including involvement • Bi/Tricompartmental of the opposite compartment, disease malaligned tibial or femoral • Grade IV OA changes with component medio-lateral subluxation (> 3-4 mm). • Symptomatic patellofemoral arthritis • < 90° flexion with flexion contracture • Active lifestyle with sporting activities • Obesity • Unstable and ACL deficient knee • High expectation for sporting activities and for increased prosthesis survival

Constrained Prosthesis (Fig. 12.8) zz zz zz

Indications: Severe deformity, collateral ligament insufficiency, bone defects. Advantage: Provides excellent stability. Disadvantages – Decreases bone stock. – Early aseptic loosening. – Recurrent instability in frontal plane. – No long-term follow-up.

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Extension Rods (Fig. 12.9) Indications zz zz zz zz zz zz

Used with constrained designs Severe deformity and bone loss Associated fractures Revision surgeries Obese Osteoporotic bone.

Advantages zz zz

Increases stability Increases longevity of prosthesis

Hinged Implants (Fig. 12.10) Indications zz zz zz zz

Salvage situations (failed revisions, tumors) Significant bone loss. Unreconstructable ligaments Reconstruction after resection of tumor around the knee joints.

Disadvantages zz zz zz

Expensive Early aseptic loosening Large bony resections.

Fig. 12.9  A TKR with tibial extension rod

Chapter 12  Implants and Patient Selection

Fig. 12.10  Hinged knee prosthesis

Various Conditions and Implant Selection zz

zz zz zz

zz zz zz

zz

Unicompartmental arthritis : Unicondylar knee arthroplasty/ high tibial osteotomy Good bone stock : All polyethylene tibia Young patient with no deformity : Cruciate retaining (CR) Mild deformity : RP (Rotating platform) or RPF or fixed bearing-posteriorly stabilized (FB-PS) Moderate deformity : FB-PS Severe deformity : FB-PS or constrained Severe deformity with bone loss : Constrained prosthesis with extension rods No extensor mechanism : Hinged prosthesis

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References 1. Joseph A Zeni Jr, and Lynn Snyder-Mackler, Clinical Outcomes After Simultaneous Bilateral Total Knee Arthroplasty: Comparison to Unilateral Total Knee Arthroplasty and Healthy Controls. J Arthroplasty. 2010; 25(4): 541-6. 2. March LM, Cross M, Tribe KL, et al. Two knees or not two knees? Patient costs and outcomes following bilateral and unilateral total knee joint replacement surgery for OA. Osteoarthritis Cartilage 2004; 12:400-8. 3. Reuben JD, et al. Cost comparison between bilateral simultaneous, staged, and unilateral total joint arthroplasty. J Arthroplasty 1998;13:2. 4. Kim YH. Incidence of fat embolism syndrome after cemented or cementless bilateral simultaneous and unilateral total knee arthroplasty. J Arthroplasty 2001; 16:730-9. 5. Bullock DP, Sporer SM, Shirreffs TG Jr. Comparison of simultaneous bilateral with unilateral total knee arthroplasty in terms of perioperative complications. J Bone Joint Surg Am 2003;85-A:1981-6. 6. Shin Y H, Kim M H, Ko J S, Park J A. The safety of simultaneous bilateral versus unilateral total knee arthroplasty: The experience in a Korean hospital. Singapore Med J 2010; 51(1) : 44 7. Adili A, Bhandari M, Petruccelli D, De Beer J. Sequential bilateral total knee arthroplasty under 1 anesthetic in patients > or = 75 years old: Complications and functional outcomes. J Arthroplasty 2001; 16:271-8. 8. Yoshiya S, Matsui N, Komistek RD , Dennis DA, Mahfouz M, Kurosaka M. In vivo kinematic comparison of posterior cruciate-retaining and posterior stabilized total knee arthroplasties under passive and weight-bearing conditions. J Arthroplasty. 2005; 20:777-83. 9. Maruyama S, Yoshiya S, Matsui N, Kuroda R, Kurosaka M. Functional comparison of posterior cruciate-retaining versus posterior stabilized total knee arthroplasty. J Arthroplasty. 2004; 19: 349-53. 10. FR Kolisek, MS McGrath, DR Marker, et al. Posterior-Stabilized Versus Posterior Cruciate Ligament-Retaining Total Knee Arthroplasty. The Iowa Orthopaedic Journal; Vol 29: 23-7 11. Giles R Scuderi, Mark W Pagnano. Review Article: The rationale for posterior cruciate substituting total knee arthroplasty Journal of Orthopaedic Surgery 2001, 9(2): 81-8 12. Laskin RS. Total knee replacement with posterior cruciate ligament retention in patient with fixed varus deformities. CORR 1996;331: 29-34. 13. Sledge CB, Ewald FC: Total knee arthroplasty experience at the Robert Breck Brigham Hospital. CORR 1979; 145: 78-84. 14. Windsor RE, Insall JN, Vince KG: Technical consideration of total knee arthrolasty after proximal tibial osteotomy. JBJS Am 1988;70:547-55. 15. Mahoney OM, Noble PC, Rhoads DD, Alexander JW and Tullos HS. Posterior cruciate function following total knee arthroplasty: A biomechanical study. J Arthroplasty 1994; 9:569-78. 16. Pagnano MW, Hanssen AD, Stuart MJ and Lewallen DG. Flexion instability after primary posterior cruciate retaining total knee arthroplasty. Clin Orthop 1998; 356:39-46. 17. Coughlin KM, Incavo SJ, Doohen RR et al (2007) Kneeling kinematics after total knee arthroplasty: anterior-posterior contact position of a standard and a high-flex tibial insert design. JArthroplasty 22:160-5

Chapter 12  Implants and Patient Selection 18. Nagura T, Dyrby CO, Alexander EJ, Andriacchi TP. Mechanical loads at the knee joint during deep flexion. J Orthop Res. 2002;20:881-6 19. Ranawat CS. Design may be counterproductive for optimizing flexion after TKR. Clin Orthop Relat Res. 2003;416:174-6. 20. Kim YH, Sohn KS, Kim JS. Range of motion of standard and high-flexion posterior stabilized total knee prostheses: A prospective, randomized study. J Bone Joint Surg Am. 2005;87:1470-5. 21. Yamazaki J, Ishigami S, Nagashima M, Yoshino S. Hy-Flex II total knee system and range of motion. Arch Orthop Trauma Surg. 2002;122:156-60. 22. Huang HT, Su JY, Wang GJ. The early results of high-flex total knee arthroplasty: a minimum of 2 years of follow-up. J Arthroplasty. 2005;20:674-9. 23. Berger RA, Rosenberg AG, Barden RM, et al. Long-term follow-up of the Miller-Galante total knee replacement. Clin Orthop Relat Res 2001;388:58. 24. Laskin RS. The Genesis total knee prosthesis: a 10-year follow-up study. Clin Orthop Relat Res 2001;388:95. 25. Ritter MA, Berend ME, Meding JB, et al. Long-term follow-up of anatomic graduated components posterior cruciate-retaining total knee replacement. Clin Orthop Relat Res 2001;388:51. 26. Aglietti P, Baldini A, Buzzi R, et al. Comparison of mobile-bearing and fixed-bearing total knee arthroplasty: a prospective randomized study. J Arthroplasty 2005;20:145. 27. Beard DJ, Pandit H, Price AJ, et al. Introduction of a new mobile-bearing total knee prosthesis: minimum three year follow-up of an RCT comparing it with a fixed-bearing device. Knee 2007;14:448. 28. Scott T. Ball, Hugo B. Sanchez , Ormonde M. Mahoney, and Thomas P. Schmalzried, Fixed Versus Rotating Platform Total Knee Arthroplasty: A Prospective, Randomized, Single-Blind Study The Journal of Arthroplasty Vol. 00 No. 0 2010 29. Morra EA, Postak PD, Plaxton NA, et al. The effects of external torque on polyethylene tibial insert damage patterns. Clin Orthop Relat Res 2003;410:90. 30. Collier MB, Engh Jr CA, McAuley JP, et al. Osteolysis after total knee arthroplasty: influence of tibial baseplate surface finish and sterilization of polyethylene insert. Findings at five to ten years postoperatively. J Bone Joint Surg Am 2005;87:2702. 31. Collier MB, Engh Jr CA, McAuley JP, et al. Factors associated with the loss of thickness of polyethylene tibial bearings after knee arthroplasty. J Bone Joint Surg Am 2007;89:1306. 32. Jordon LR, Olivo JL, Voorhorst PE. Survivorship of analysis of cementless meniscal bearing total knee arthroplasty. Clin Orthop 1997; 338: 119-23. 33. Kenneth A. Greene. Gender-specific design in Total Knee Arthroplasty The Journal of Arthroplasty 2007; 22 (7) Suppl. 3: 27-31. 34. Dodd CAF, Hungerford DS, Krackow KA. Total knee arthroplasty fixation: comparison of the early results of paired cemented versus uncemented porous coated anatomic knee prostheses. Clin Orthop 1990; 260:66-70. 35. Collins DN, Heim SA, Nelson CL, Smith P 3rd. Porous-coated anatomic total kneearthroplasty: a prospective analysis comparing cemented and cementless fixation. Clin Orthop 1991;267:128-36. 36. Khaw FM, Kirk LMG, Morris RW, Gregg PJ. A randomised, controlled trial ofcemented versus cementless press-fit condylar total knee replacement. J Bone JointSurg [Br] 2002;84-B:658-66.

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Section 2  Knee Arthroplasty 37. Whiteside LA. Cementless total knee replacement: nine-to 11-year results and 10-year survivorship analysis. Clin Orthop 1994;309:185-92. 38. Watanabe H, Akizuki S, Takizawa T. Survival analysis of a cementless, cruciate-retaining total knee arthroplasty. Clinical and radiographic assessment 10 to 13 years after surgery. J Bone Joint Surg Br. 2004; 86(6):824-9. 39. Callaghan JJ,  Liu SS. Cementless tibial fixation in TKA: a second coming. Orthopedics. 2010;33(9):655. 40. Shen B, Yang J, Zhou Z, Kang P, Wang L, Pei F. Survivorship comparison of allpolyethylene and metal-backed tibial components in cruciate-substituting total knee arthroplasty--Chinese experience. Int Orthop. 2009;33(5):1243-7 41. Gio TJ, Bowman KR. A randomized comparison of all polyethylene and metal- backed tibial components. CORR2000;380: 108-15. 42. Bert JM. Unicompartmental Knee Replacement. Orthop Clin N Am 36 (2005) 513-22. 43. Parrate S, Argenson JNA, Dumas J, Aubaniac JM, Pagnano MW: Unicompartmental knee arthroplasty for avascular osteonecrosis. Clin Orthop Relat Res 2007, 464:37-42. 44. Saito T, Takeuchi R, Yamamoto K, Yoshida T, Koshino T: Unicompartmental knee arthroplasty for osteoarthritis of the knee. J Arthroplasty 2003, 18:612-18. 45. Bert JM. Universal intramedullary instrumentation for unicompartmental knee arthroplasty. Clin Orthop 1991; 271:79-87. 46. Gioe TJ, Killeen KK, Hoeffel DP, et al. Analysis of unicompartmental arthroplasty in a community-based implant registry. Clin Orthop 2003;416:111-9s. 47. Cartier A, Sanouiller JL, Grelsamer RP. Unicompartmental knee arthroplasty surgery. 10-year minimum follow-up period. J Arthroplasty 1996;11:782-8. 48. Kellgren JH, Lawrence JS: Radiological assessment of osteoarthritis. Ann Rheum Dis 1957; 16: 494–501. 49. Joern W.-P. Michael, Klaus U. Schlüter-Brust, Peer Eysel. The Epidemiology, Etiology, Diagnosis and Treatment of Osteoarthritis of the Knee. Deutsches Ärzteblatt International | Dtsch Arztebl Int 2010; 107(9): 152-62. 50. Matsunga D, Akizuki S, Takizawa T, Yamazaki I, Kuraishi J: Repair of articular cartilage and clinical outcome after osteotomy with microfracture or abrasion arthroplasty for medial gonarthrosis. Knee 2007; 14: 465-71. 51. Horas U, Pelinkovic D, Herr G, et al.: Autologous chondrocyte implantation and osteochondral cylinder transplantation in cartilage repair of the knee joint. A prospective, comparative trial. J Bone Joint Surg (Am) 2003; 85: 185-92.

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Perioperative Management of Total Knee Arthroplasty

Preoperative clinical evaluation zz zz zz

zz

zz zz zz

zz

Thorough clinical history. Assess the indications and contraindications. Assess the patient expectations, occupation and discuss the needed lifestyle modifications after the knee arthroplasty. Assess the range of motion, deformity (varus, valgus, flexion or combined deformity, whether correctable or not) and instability (severe instability may require constrained prosthesis). Non-correctable deformities require release. Look for range of movements and deformities of hip on affected site. Informed and written consent for surgery. One dose of intravenous antibiotics (cefotaxime/ceftriaxone) in the morning or one hour before starting the surgery. Avoid aminoglycosides (gentamycin, amikacin) in renal disease. Manage medical conditions as described in chapter on perioperative management of THR.

Preoperative Radiological Evaluation Radiographs Standing long-leg anteroposterior radiograph, lateral and skyline view: Standing long-leg anteroposterior radiograph (Figs 13.1A and B) To assess the deformity, mechanical and anatomical axis, bone defects, mediolateral subluxation, and templating for sizes of components. zz Lateral view (Fig. 13.2): Subluxation, bone defects, posterior osteophytes and position of patella. zz Sky line view: Patellar tilt, hypoplasia of condyle or trochlea. zz

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A

B

Figs 13.1A and B  Standing AP view of both knees with osteoarthritis with subluxation and varus deformity

Fig. 13.2  Posterior osteophytes and loose bodies

Chapter 13  Perioperative Management of Total Knee Arthroplasty

Postoperative clinical management Immobilization: Knee brace or cylinder slab may be given for initial 2-3 days. Immediate postoperative care: Check for soakage of dressing (for mild soakage, do suprabandaging), pulse, BP, respiratory rate, O2 saturation, blood in suction drain (one ring ≈ around 100 ml, replace accordingly), distal pulses (dorsalis pedis and posterior tibial artery), color (should be pink) and capillary filing (normally < 2 seconds) of toes, extension of toes and foot (common peroneal nerve). Wound inspection: Done on 2nd postoperative day and dressing debulked. Any suspicious looking discharge should be sent for culture and sensitivity. Analgesic: Morphine top-up (12 hrly) through epidural catheter for 2-3 days with injection diclofenac sodium (renal, asthmatic or allergic disease: pethidine + phenargen/tramodol) on SOS basis followed by oral diclofenac/aceclofenac sodium (renal, asthmatic or allergic disease: Tramodol with or without paracetamol) till suture removal. Antibiotic and prophylaxis for DVT: See chapter on Complications of TKR. Suture removal and mobilization: Static quadriceps on first 1-2 days, weight bearing mobilization with walker (Figs 13.3 to 13.5) on 2nd to 3rd day (depending on the

Fig. 13.3  Venous pump in a patient after bilateral total knee arthroplasty

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Fig. 13.4  Patient standing on 3rd postoperative day

Fig. 13.5  Patient sitting on the side of the bed with 90° flexion at 2 weeks after surgery

Chapter 13  Perioperative Management of Total Knee Arthroplasty

bone quality, fixation of component, intraoperative bone cracks, soft tissue repair), knee flexion from 2nd to 3rd day (try to get 90° flexion till suture removal) and suture/staples removal on 14th postoperative day after wound inspection for healing to avoid gaping (if still wide gaping, delay for 5-7 days, if minimal or doubtful gaping, remove alternate sutures). Walking aid preferably walker for first-two weeks followed by stick for next 2-3 weeks. Start stair climbing after 2 weeks in midvastus or subvatus approach and avoid cross legged sitting/squatting forever.

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Surgical Approaches and Technique of Primary Total Knee Arthroplasty Surgical Approaches With anterior midline skin incision, medial parapatellar and midvastus approaches are the most commonly used for primary total knee arthroplasty (Table 14.1).

Basic Principles (Tips and Tricks) of Soft Tissue Release to Achieve Stable Joint zz zz zz

zz zz zz zz

Stepwise sequential release Optimum subperiosteal release with osteotome or cautery Laminar spreaders or spacer block to judge to rectangular and equal flexion and extension space Achieve full extension and good flexion of knee Achieve good medial-lateral balance at full extension, 90° of flexion and mid-flexion Proper patellar tracking Check balancing at every step (preoperatively, after induction of anesthesia, before and after bone cuts with insertion of trial and final prosthesis).

Basic Principles (Tips and Tricks) for Optimum Bone Cuts zz

zz

zz

zz

Protect and preserve bone and soft tissues (medial-lateral soft tissue sleeves, ligamentum patellae and popliteus tendon). Cross check accuracy of cuts by using multiple references (Angel wing, saw blade, epicondylar axis, Whiteside line, posterior condylar axis or proximal tibial articular surface) before cut and accuracy of surface after the bone cut. Consider bone quality (careful bone cutting and impaction during cementing for soft bones, e.g. rheumatoid arthritis, use sharp new blade for cutting hard bone in osteoarthritis to prevent wrong cut due to kinking of blade by pressure of hard bone) There are no fixed sequences for bone cuts (tibia first or femur first; distal femur or anterior femoral cut). But beginner should try to follow one sequence (tibial cut,

Chapter 14  Surgical Approaches and Technique of Primary Total Knee Arthroplasty Table 14.1  Comparison of various surgical appraoches to TKR Approaches1,2

Advantages

Subvastus (Southern): • Incise the vastus medialis fascia medial to patella and lift it from muscle by blunt dissection • L ift the inferior edge of the vastus medialis muscle from the periosteum and medial intermuscular septum proximally and perform L-shaped arthrotomy

(Fig. 14.1) • It does not disturb extensor mechanism •A  llows better judgment of patellar tracking • L ess anterior knee pain, patellar fracture, patellar loosening (due to intact patellar blood supply) • L ess postoperative pain and strong intact extensor mechanism

Midvastus (Fig. 14.2) Incision is given in the direction of fibers and through the midsubstance of vastus medialis starting from the superior medial border of patella, curving along the anteromedial border of patella, distally medial to ligamentum patellae on the medial surface of proximal tibia Lateral approach Incision along the lateral border of quadriceps tendon

Anteromedial parapatellar approach Incision along the medial border of quadriceps tendon, curving distally around the medial border of patella up to tibial tuberosity (try to keep medial to tibial tuberosity)

Disadvantages •  Not useful for obese patient, revision surgery, previous arthrotomy or high tibial osteotomy •  Eversion of patella is difficult

• Insertion of vastus medialis into the medial border of quadriceps tendon is not disturbed •A  voids lateral release •A  llows early recovery of the postoperative extensor mechanism •  Better patellar tracking

•  Difficult for obese, previous high tibial osteotomy, patient with less than 80˚ of flexion

• Indicated in fixed valgus deformity •A  llows direct exposure of the lateral pathology • Allows better exposure of the posterolateral corner due to medial displacement or eversion of extensor mechanism and internal rotation of tibia • Intact vascularity and better patellar tracking

• Technically demanding due to unfamiliar anatomy • Medial eversion and displacement of extensor mechanism is more difficult than the lateral one

(Fig. 14.3) Indicated in patients with knee deformities (varus, valgus, flexed knee) Better exposure of distal femur and proximal tibia

• Extensor mechanism is affected; patellar maltracking

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V-Y Plasty or Tibial Tubercle Osteotomy zz zz zz

Used for stiff knee Tibial tuberosity osteotomy is preferred over V-Y plasty Tibial tuberosity osteotomy have less possibility of extensor lag and other complications. anterior cut, distal cut, check extension space, sizing of femur (see the proposed flexion space), 4 in one jig (posterior cut, posterior chamfer, anterior chamfer, anterior cut), notch cut, tibial sizing, check stability with trial femoral prosthesis, trial tibia and minimum spacer (8, 10 size), prepare tibia, and patella (patellar cut) only.

Technique for Primary Total Knee Arthroplasty (Cemented Posterior Stabilized Knee) zz zz zz

zz

Drape the knee (Fig. 14.4) Inflate the tourniquet Midline skin incision extending slightly medial to tibial tuberosity in the lower part (Fig. 14.5) Raise medial and lateral skip flaps deep to deep fascia otherwise flap will necrose (Fig. 14.6)

Fig. 14.1  Planes of dissection in parapatellar and midvastus approach

Chapter 14  Surgical Approaches and Technique of Primary Total Knee Arthroplasty

Fig. 14.2  Plane of dissection for midvastus approach (arrow mark)

Fig. 14.3  Plane of dissection for medial parapatellar approach

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zz zz

Use midvastus approach and before cutting put a marking suture at the angle of attachment of vastus medialis with patella (Fig. 14.7) Cut the muscle with cautery or knife (Fig. 14.8) Excise the synovium from the suprapatellar pouch (Fig. 14.9)

Fig. 14.4  Draped knee with marked tibial tuberosity (T) and joint line (JC)

Fig. 14.5  Marking for midline skin incision, distal part medial to tibial tuberosity

Chapter 14  Surgical Approaches and Technique of Primary Total Knee Arthroplasty

Fig. 14.6  Lifting the medial and lateral skin flaps zz

zz

Distally do the medial release medial to patellar ligament by rotating the leg externally. Also release upper border of lateral condyle Evert the patella (Fig. 14.10)

Fig. 14.7  The arrow at the marking suture for the angle of vastus medialis attachment with patella

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Partially excise the fat from infrapatellar fat-pad (Fig. 14.11) Cut the cruciate ligaments Excise the meniscus (Fig. 14.12) Remove the anterior osteophytes (Fig. 14.13).

Fig. 14.8  Cutting the synovium with cautery

Fig. 14.9  Clean suprapatellar pouch after synovectomy

Chapter 14  Surgical Approaches and Technique of Primary Total Knee Arthroplasty

Fig. 14.10  Eversion of patella with flexed knee and release of lateral border of patella

Tips of patellar eversion zz zz zz zz

Adequently raise lateral skin, subcutaneous and deep fascia flap Release lateral border of patella with cautery Release lateral border of tibia proximally Circumcision of patella.

Bone Cuts There are total six femoral cuts (anterior, distal femoral, posterior, anterior and posterior chamfer cut, intercondylar notch cut), two tibial cuts (proximal and stem cut) and optional patellar cut. Over all effects of wrong bone cuts includes pain, decreased ROM, instability, anterior knee pain with or without patellar maltracking and early aseptic loosening.

Tibial Cut (Figs 14.14 to 14.20) Cut is made at 90° to long axis (horizontal to ground) of tibia (and with 0-5° posterior slope) with exramedullary rod aligning distally along the mid of anterior surface of ankle joint (distally along the 2nd toe) and proximally at the junction of medial one third and lateral two-third of tibial tuberosity (for correct rotation, center of tibial tray should be at this junction,). Excesvsive internal rotation of tibial component lead to posterolateral slope and excessive external rotation result in posteromedial posterior slope. This cut affects both spaces (flexion and extension). Anterior, posterior and distil femoral cuts are parallel to this cut in midflexion and in extension respectively.

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Fig. 14.11  Debulking of the infrapatellar fat pad

Fig. 14.12  Removal of the posterior part of medial meniscus

Chapter 14  Surgical Approaches and Technique of Primary Total Knee Arthroplasty

Fig. 14.13  Removal of anterior tibial osteophytes

Fig. 14.14  Extramedullary tibial zig parallel to tibia and pointing towards second toe. Also note the posteior slope

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A

B

Figs 14.15A and B  Varus/valgus cut or excessive anterior or posterior tibial slope due to improper mediolateral or anteroposterior placement of extramedullary tibial cutting zig

Fig. 14.16  Stylus on more deformed medial tibial plateau

Chapter 14  Surgical Approaches and Technique of Primary Total Knee Arthroplasty

Cut should remove minimum 8-10 mm thickness of tibia; inadequate bone removal lead to tightening of both spaces (flexion/extension). Anterior tibial slope contrary to normal posterior slope reduces posterior flexion space, limit the posterior rollback and may results in pain and decreased ROM. Excessive posterior slope >5-10° may increase mid flexion instability. Average increase of 1.7° of flexion for every 1° increase in

Fig. 14.17  Hole of zig in line with medial third of the tibial tuberosity (with blue marker)

Fig. 14.18  Cross-checking of the tibial cut thickness with angel wing

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Fig. 14.19  Cut tibial surface with removal of posterior part of medial meniscus with cautery

Fig. 14. 20  Approximate extension space assessment by using the minimum spacer (18-20 mm)

Chapter 14  Surgical Approaches and Technique of Primary Total Knee Arthroplasty

A

B

Figs 14.21A and B  Anterior cut (A), the epicondylar axis (E), posterior condylar axis (PC) and the tibial cut surface are parallel to each other; also shows the whiteside line (W) and femoral entry point (EP) just anterior to ACL attachment

Fig. 14. 22  Femoral entry in the middle of the distal articular surface of femur

posterior slope is achieved. After tibial cut remove posterior remaining part of meniscus and osteophytes (Fig. 14.15). zz After tibial cut check rough extension space (Fig. 14.16).

Anterior Femoral Cut (Figs 14.21 to 14.27) It is an important cut to prevent malrotation, notching, anterior overstuffing and patellar maltracking. Insert the intramedullary rod (long better than the short and should be in the center of canal) by making an entry point (either 5 mm anterior to the attachment of PCL or mid point of medial and lateral femoral margin or 5 mm

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Fig. 14.23  Intramedullary rod with anterior cutting zig with desired 6° of valgus and adjusted for right-left should be flushed with the distal articular surface of the femoral condyles

medial to the mid point) with jig in 5-7° valgus and 3-5° external rotation (increased external rotation causes increased midflexion medial space and internal rotation causes lateral tilting of patella). Stylus should be touching the prominent lateral most part of anterior surface of lateral condyle (cross check with the Angel wing touching the anterior surface of lateral femoral condyle) and cut the bone. Cut surface and the resected bone looks like a piano (Grand piano sign) with cut lateral condyle thicker than medial condyle. Extension cut will cause notching while flexion cut will cause anterior overstuffing.

Distal Femoral Cut (DFC) (Figs 14.28 to 14.31) Remove the intramedullary rod and attach distal cutting zig to pin over anterior surface. Distal femoral cut thickness should be equal to thickness of prosthesis and at 90° angle to the mechanical axis of femur. Valgus (usually 5-7°) be taken either according to neck shaft angle (coxa vara > 5°, coxa valga < 5°). Extra or excessive DFC should be avoided to prevent joint line elevation, patellar maltracking, extension instability, pain and decreased ROM (>10 mm joint line elevation decrease flexion by > 25%). In fixed flexion deformity, extra distal femoral cut up to 4 – 6 mm can be taken. zz After DFC, put a spacer and check medial and lateral stability zz Now decide the size mid flexion on space depending on definitive prosthesis (Figs 14.32 and 14.33). Now decide the mid-flexion space depending on the size of definitive prosthesis. zz Take the 4 in 1 cutting zig of same size and complete the other cuts (Figs 14.31A and B)

Chapter 14  Surgical Approaches and Technique of Primary Total Knee Arthroplasty

Fig. 14.24  Checking thickness of the anterior cut with angel wing, it should flush with most prominent part of the lateral femoral condyle

A

B

Figs 14. 25A and B  External rotation zig either parallel (A) or slightly in external rotation (B) to cut tibial surface

Posterior Femoral Condyle Cut (Figs 14.34 and 14.35) This cut is made by jig with knee in 90° flexion and with 3° external rotation (inadequate rotation leads to trapezoidal midflexion space than a rectangular space). There are following three methods for this cut (combine more than one method for accuracy).

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A

B

Figs 14. 26A and B  Anterior cut has been taken and showing giant piano sign (A) shape of cut surface and Piano shape of bone removed (B) by the cut

Fig. 14. 27  Cross check the anterior cut with a flat rasp; should be equally flushed on both cut surfaces of the condyles

Posterior condylar axis: A line (Figs 14.25A and B) passing through the lower most part of both femoral condyles. Cut is made at an angle of 3° external rotation to this axis in 90° flexion of knee (it cuts more thickness of medial condyle than lateral condyle). But this method is not good for valgus knee (rheumatoid arthritis) having either hypoplastic lateral femoral condyle or extensive wear of both condyles (epicondylar axis may be used for cut).

Chapter 14  Surgical Approaches and Technique of Primary Total Knee Arthroplasty

A

B Figs 14. 28A and B  Intramedullary rod has been removed and checking the thickness of the distal femoral cut with an Angel wing (A) after putting the distal cutting zig, it should be flush with the notch area (B)

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Fig. 14.29  The cutting of the distal femoral cut with saw with a broad osteotome protecting the cutting of the tibial surface. Cut should be away from the medial collateral ligament (shown with a tip of the artery forceps)

Fig. 14.30  Attached distal femoral zig and distal femoral cut has been taken

Chapter 14  Surgical Approaches and Technique of Primary Total Knee Arthroplasty

A

B Figs 14.31A and B  The extension gap (A) after putting the spacer and checking the medial (B) and lateral stability

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Epicondylar axis: A line (Figs14.21A and B) joining the most prominent part of two epicondyles make epicondylar axis. Cut should be made parallel to this line. Whiteside line: It extends (Figs14.21A and B) from the base of femoral trochlear groove to the apex of the intercondylar notch. It is not reliable in revision surgery. Tibial cut surface (gap technique): With jig in situ, take saw blade in hand and align with the proposed level of cut; this should be parallel to cut surface (Fig. 14.25A & B) of proximal tibia. Cut should ensure 3° of external rotation for equalizing the space (lateral is more than medial due to tibial cut at 90° to horizontal plane). Size of zig should be adequate (small size cuts more posterior condyle and leads to increased midflexion space with instability). Magnitude of cut correlates well with final flexion (every 1 mm loss of PFC offset causes 6° loss of flexion).

Femoral Notch Cut (Figs 14.36 and 14.37) This cut is lateralized and bone should be cut at right angle close to inner margin of jig with osteotome or saw.

Fig. 14.32  The sizing with a zig (it should be flushed with anterior and posterior cortex, see the number against the marker, here it is 9)

Chapter 14  Surgical Approaches and Technique of Primary Total Knee Arthroplasty

Fig. 14.33  Size can be cross checked by taking the prosthesis of measured size (like here using 7 size; if it is 9 then take 9, should be centered over the notch and should not extend beyond the outer margin of medial and femoral condyles)

Ligament Release for CR Prosthesis Measured Resection Technique Anterior and posterior femoral cuts are taken at fixed measured angles referenced from anatomical landmarks (transepicondylar axis, Whiteside line and posterior condylar reference). Ligament release is done after implantation of prosthesis in extension.

Gap Technique Tight ligaments are released (tightest first) after proximal tibia cut, then a laminar spreader or a tensor may be used to tension the ligaments and the anterior and poste­ rior femoral bone cuts are made parallel to the tibial cut based on the ligament tension. zz Insert trial femur and tibia with approximate sized liner and check stability and patellar tracking (Figs 14.38A to D) zz Now wash the prepared femur and tibia.

Patellar Cut (Figs 14.39 and 14.40) Circumcision should be done for denervation (less patellar pain) and remove osteophytes to clear the surface for estimating the bone removal with the help of patellar zig. Patella prosthesis should be medialized on a 12-15 mm of native patella. Patellar tracking should be checked with no touch technique (no thumb on the patella)

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A

B Figs 14.34A and B  Hohmann retractor with broad osteotome to avoid damage to MCL and tibial cut

Chapter 14  Surgical Approaches and Technique of Primary Total Knee Arthroplasty

Fig. 14.35 Notch cutting zig in situ (should be flushed over the anterior chamfer and distal femoral cut, should be centered over the femoral entry point)

Fig. 14.36  Well placed notch cutting zig

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Fig. 14.37  Complete notch cut

from extension to flexion of knee (there should be no lateral tilting of patella and it should remain in contact with anterior surface of medial condyle throughout the extension and flexion movements) preferably after release of tourniquet. Patellar maltracking may occur due to internal rotation of components, medialization of notch cut, lateralization of patella or elevation of joint line. Patellar maltracking may require lateral release which can be done from inside (release < 5 mm to avoid injury to common peroneal nerve) or from outside (gentle longitudinal releasing incision just below the lateral patellar margin till the synovium becomes visible and it should not extend beyond lateral superior margin of patella to avoid damage to blood supply of patella). Inadequate bone thickness3 removal form patella leads to anterior overstuffing (anterior knee pain and 3° decrease in ROM for every 2 mm thickness). zz Apply some cement over femur and tibia in early phase and over the implant (in doughy stage), insert the definitive tibia, femur, patella and check range of motion, stability and patellar tracking (Figs 14.39 to 14.41).

Common mistakes and their causes zz

zz

Instability in flexion: Undersized femoral component (increase resection of PFC), anterior translation and flexed anterior femoral condyle, rotational malalignment of femur and tibial stem, increased tibial posterior slope. Instability in extension: Asymmetric instability due to improper bone cuts or soft tissue release or both, symmetric instability due to excessive removal of bone (DFC) or generalized laxity.

Chapter 14  Surgical Approaches and Technique of Primary Total Knee Arthroplasty

A

B Figs 14.38A and B

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C Fig. 14.38C Figs 14.38A to C  (A) Stability in extension; (B) Stability and alignment in flexion; (C) Alignment in extension

D Fig. 14.38D  Checking patellar tracking. Note the no thumb rule.

Chapter 14  Surgical Approaches and Technique of Primary Total Knee Arthroplasty

A

B Figs 14.39A and B  (A) Early stage cement applied before putting original femoral component with drilling of the sclerotic tibial cut surface; (B) Original femoral component in situ and cement over the tibial surface

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Fig. 14.40  All the three definitive components implanted with cement

Fig. 14.41  The well positioned patella (not lifting laterally even without any thumb touch: No thumb technique for checking patellar tracking)

Chapter 14  Surgical Approaches and Technique of Primary Total Knee Arthroplasty zz zz zz

Inadequate post clearance due to reverse tibial slope or posterior osteophytes. Anterior over stuffing due to inadequate anterior femoral cut or over size patella. Patellar maltracking due to internal rotation of components, medialized notch cut, lateralized patella, elevation of joint line or overstuffing.

Criteria for Equalizing Flexion and Extension Gaps and Bone Cuts If both extension and flexion space are tight: Remove tibia If extension is tight and flexion is normal: Posterior release and remove distal femur If extension is normal and flexion is tight: ↓ Femur size/ ↑ posterior slope of tibia If extension is normal and flexion is loose: ↑Femur size or distal femur can be resected and use thicker tibial insert If extension is loose and flexion is normal: Distal augmentation of femur or downsize femur and use thicker tibial insert If both extension and flexion space are loose: Large tibial insert.

Factors Affecting Flexion after TKR Preoperative flexion is the single most important factor affecting the postoperative flexion.4 Others variables reducing postoperative flexion includes female sex, obesity, previous knee surgeries, associated co-morbidities,5 component malposition, patellofemoral overstuffing, improper size of components, inadequate flexion gap balancing, posterior tibial or femoral osteophytes.6-8

References 1. Steven H. Stern. Surgical exposure in the total knee arthroplasty in Orthopaedic In: Robert et al. (Eds). Knowledge Update, Hip and Knee reconstruction 3 (1st edn); 2007 pp. 3-15; Jaypee Brothers Medical Publishers (P) Ltd, New Delhi, India. 2. Andrew H. Crenshaw Jr. Surgical Techniques and Approaches in Canale ST and Beaty JH (eds). Camplbell’s Operative Orthopaedics 11th edn; 2008 pp. 4-14; Mosby, Elsevier, Philadelphia USA. 3. Briard JL, Hungerford DS. Patellofemoral instability in total knee arthroplasty. J Arthroplasty 1989;4(Suppl): 587-97. 4. Dennis DA, Komistek RD, Scuderi GR, Zingde S. Factors affecting flexion after total knee arthroplasty. Clin Orthop Relat Res 2007;464:53-60. 5. Fisher DA, Dierckman B, Watts MR, Davis K. Looks good but feels bad: factors that contribute to poor results after total knee arthroplasty. J Arthroplasty 2007;22(6 Suppl 2):39-42. 6. Sultan PG, Most E, Schule S et al. Optimizing flexion after total knee arthroplasty: advances in prosthetic design. Clin Orthop Relat Res 2003;416:167-73. 7. Kurosaka M, Yoshiya S, Mizuno K, Yamomoto T. Maximizing flexion after total knee arthroplasty: The need and the pitfalls. J Arthroplasty 2002;17:59-62. 8. Michael Murphy and Simon Journeaux and Trevor Russell. High-flexion total knee arthroplasty: A systematic review. International Orthopaedics (SICOT) 2009;33:887-93.

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chapter

Complex Primary Total Knee Arthroplasty Varus Knee Varus deformity is more common in osteoarthritis of knee. Tissues are contracted on the medial side and are lax on the lateral side.

Contracted Soft Tissues on the Medial Side zz

zz zz

Posteromedial corner: Semimembranosus insertion, medial capsule and deep medial collateral ligament Superficial medial collateral ligament Pes anserinus tendon.

Soft Tissue Release (Tips and Tricks; Fig.15.1)1 zz

zz

zz zz zz

zz

zz

zz

Initial exposure should include the release of deep collateral ligament from the tibia up to the posteromedial corner of the tibia. Remove medial osteophytes from tibia and femur to prevent tightness of the medial sleeve. Excise medial meniscus. PCL tight: Release it. If medial tightness persists: Do the sequential release from tibia further posteriorly and inferiorly and recheck the medial tightness after release of each tight tissue. Flex and externally rotate tibia and release semimembranosus from the posteromedial corner. Release superficial collateral ligament and pes anserinus insertion. If still tight: Subperiosteal release from the tibia distally up to 4-8 cm (should be the last option to avoid valgus instability). Sequence of release: Deep MCL and capsule and excision of medial meniscus + osteophytes from medial side of tibia and femur → PCL → semimembranosus aponeurosis, superficial collateral ligament, pes anserinus → subperiosteal release from tibia upto 4-8 cm distally (last resort).

Chapter 15  Complex Primary Total Knee Arthroplasty

Fig. 15.1  Complete medial release and lateral release being done

Valgus Knee (Figs 15.1 and 15.2) Problems zz zz zz zz zz

Bone loss or hypoplastic lateral femoral and tibial condyle Soft tissues contracted on the lateral side Lax and weak medial sleeve Patellar maltracking Acute correction of combined flexion and valgus deformities can cause common peroneal nerve palsy. It can be prevented either by exposure and release of the CPN or immobilizing the knee postoperatively in some degree of flexion to allow gradual correction.

Contracted Soft Tissue on the Lateral Side zz zz zz zz zz

Iliotibial band Lateral collateral ligament Arcuate ligament: Posterolateral capsular complex Popliteus tendon Lateral head of gastrocnemius.

Soft Tissue Release (Tips and Tricks) zz zz

Minimal medial side release Do sequential release of the tight structure on the lateral side and recheck lateral tightness after release of each structure on the lateral side

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Fig. 15.2  Removal of the lateral femoral osteophytes

zz

zz zz

zz zz

Incise the arcuate ligament: Posterolateral capsular complex horizontally at the level of tibial bone cut and divide iliotibial band If PCL tight: Release it If lateral structures are still tight: Release lateral collateral ligament and popliteus tendon Release the lateral head of gastrocnemius for associated flexion deformity Usually thick insert or constrained implant needed in presence of incompetent MCL.

Sequence of release: Posterolateral capsule → Iliotibial band, and PCL and lateral collateral ligament → Popliteal tendon → Lateral head of gastrocnemius (for associated flexion deformity). Pie crusting technique: Elkus described this technique for severe valgus knee. This involves sequential palpation of tight soft tissues and release by multiple stab punctures.

Fixed flexion deformity of knee (FigS 15.3 to 15.6) zz

zz zz

zz zz zz

Release the posterior capsule proximally for a small distance above the femoral condyles after the posterior condylar cut Remove posterior osteophytes from tibia and femur If still less posterior recess: Release posterior capsule further up to posterior surface of femur Medial head of gastrocnemius or extra distal femoral cut should be the last resort Flexion deformity (> 60°): Two staged procedure. In cases of inflammatory arthritis around 5-10° of flexion deformity can be left and it corrects well in the postoperative period with physiotherapy.

Chapter 15  Complex Primary Total Knee Arthroplasty

Fig. 15.3  Removal of the posterior osteophytes to clear posterior recess

Fig. 15.4  Clear posterior recess

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Fig. 15.5  Residual flexion deformity after TKR on 2nd postoperative day

Fig. 15.6  Complete correction of flexion deformity at 2 weeks in a rheumatoid patient

Chapter 15  Complex Primary Total Knee Arthroplasty

Stiff Knee zz zz

zz zz zz

Most difficult knee Proximal soft tissue release (V-Y plasty) and tibial tubercle osteotomy may be required1 Soft tissue release should be gradual and sequential Adequate postoperative physiotherapy and use of CPM machine Postoperative flexion may be < 90°.

Patellar Tracking zz zz zz zz zz

Preferably checked after tourniquet release Preoperative thickness = Postoperative thickness Circumcision and excision of the osteophytes Should be medialized On table patellar maltracking: Lateral release by inside-out or outside-in technique (Fig. 15.7) till the synovial layer is exposed. Do not go beyond 5 mm to avoid injury to common peroneal injury in inside-out method.

Bone Loss zz zz

zz zz

Varus and valgus knees have defects on medial and lateral sides respectively Minimal defects (Fig. 15.8) are managed by making drill hole or putting screws and cement Large defects (Fig. 15.9) are managed by bone grafts or metal wedges It is safer to use extension rods in these situations.

Fig. 15.7  Lateral release from outside, do not divide synovium to avoid damage to blood supply of patella

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Fig. 15.8  Small contained bone defects

Fig. 15.9  Reconstruction of large defects with bone graft fixed with screw

Reference 1. Crockarell JR Jr, Guyton LJ. Arthroplasty of knee in Canale ST, Beaty JH (Eds). Camplbell’s Operative Orthopaedics 11th edn; Philadelphia: Mosby, Elsevier; 2008 pp. 241-99.

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Complications of Total Knee Arthroplasty Complications after Total knee replacement Infection (Fig. 16.1) A number of comorbidities have been shown to be associated with increased risk of infection. These include previous open knee surgeries, immunosuppressive therapy, hypokalemia, poor nutrition, diverticulosis, infection elsewhere, diabetes milletus, obesity, smoking, renal failure, hypothyroidism, and alcohol abuse. Diabetes increases the risk of wound complications and infection by following ways: zz zz zz

zz zz zz

zz

zz

It delays collagen synthesis and decreases wound strength. It impairs the delivery of blood and oxygen. Nicotine and other byproducts of smoking cause vasoconstriction, decreased proliferation of red blood cells, fibroblasts, and macrophages; decreases oxygen transport and metabolism; and inhibits enzymes necessary for oxidative metabolism and cellular transport. Reported rate of infection varies from 1.6 to 3%. Get a good perioperative diabetic control. Perioperative intravenous cefotaxime or ceftriaxone with gentamycin (one preoperative dose) should be given for next 5 days followed by oral cefixime/ cefuroxime/augmentin till suture removal. Early (< 4 week postoperative) or acutely painful, red, swollen knee should be opened and thorough debridement should be done. Antibiotics should be continued for six weeks (2 weeks IV in hospital, 4 weeks oral at home) Radiological changes (bone resorption at bone-cement interface, bone cyst, periosteal reaction), ESR and CRP (peak reaches 48 to 72 hours after TKR and return to normal within 3 weeks) help in detection and follow-up during treatment.

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Section 2  Knee Arthroplasty

Fig. 16.1  Infection in a diabetic patient after TKR

Thromboembolism (Fig. 16.2) It is less in our setup without any obvious known reasons. Western reports suggest high prevalence (40-84%) of DVT after TKR due to various predisposing factors including age > 40 years, previous history of thromboembolism, varicose veins, estrogen therapy, hypertension, ischemic cardiac disease, prolong immobilization, obesity and malignancies. Painful, warm, red, swollen leg with positive calf tenderness or Homan’s sign (calf pain on dorsiflexion of foot) suggests DVT, which can be confirmed by Duplex ultrasound. It can be prevented by prophylactic treatment with low molecular weight heparin (may cause hematoma, infection, bleeding) or warfarin in hospital and by oral asprin/warfarin up to 7-10 days. Physical preventive measures include stocking, foot pump, and early mobilization. Previous h/o thromboembolism, varicose veins and ischemic cardiac disease are the three genuine indications of chemoprophylaxis against DVT.

Chapter 16  Complications of Total Knee Arthroplasty

Fig. 16.2  Discoloration of the skin after TKR due to low molecular weight heparin

Vascular Insufficiency Reported rate ranges from 0.03–0.2% and is more in patients with peripheral vascular disease.

Nerve Palsy Common peroneal nerve palsy is seen 0.3 – 1.8% of rheumatoid patients and in patients with combined fixed flexion and valgus deformity undergoing TKR.

Periprosthetic Fracture (Fig. 16.3) Supracondylar fractures (0.3–2%) of the femur tend to occur in patients having osteoporosis, rheumatoid arthritis, steroid therapy, femoral notching and trauma. Usually are treated by ORIF with locking plate, intramedullary nail or revision arthroplasty. Fracture of tibia is very rare.

Instability Usually due to wrong bone cuts, malpositioned components and inadequate soft tissue balancing.

Complications of Patellar Resurfacing zz zz zz zz zz zz zz

Fracture Maltracking/instability Aseptic loosening Polyethylene wear Anterior knee pain due to over or undersized patellar component Avascular necrosis of patella Patellar clunk syndrome.

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Fig. 16.3  Periprosthetic fracture after TKR

Patellar Clunk Syndrome Painful clunk occurring during knee movement from flexion to extension constitutes patellar clunk syndrome. It is due to formation of a fibrous nodule at the junction of proximal quadriceps tendon and proximal pole of patella because of impingement of anterosuperior part of intercondylar notch area of femoral component on the proximal part of quadriceps tendon. It may be seen in oversized femoral components, abnormal proximally placed patellar prosthesis or due to irritation of quadriceps tendon over the anterior flange of femoral component. Treatment is surgical removal of fibrous nodule with or without revision of patellar component.

Index Page numbers followed by f refer to figure and t refer to table

A Acetabular component 19, 35 index 29f labrum 3 reaming 58 templating 33f Acetabulum 3 Allis method 81 Ankylosing spondylitis 49 Anterior cruciate ligament 85 femoral cut 129 knee pain 155 superior iliac spine 88f Artery forceps 88f, 134f Arthritic hip 9 Aseptic loosening 39, 155 of acetabular and femoral components 16f of cup 38 of joint prosthesis 39t Assessment of acetabular cup positioning 40f stability of joint 65f Autologous chondrocyte transplantation 95 osteochondral transplantation 95 Avascular necrosis of patella 155 Axis of lower limb 91

B Bilateral ankylosed hip 74f total hip arthroplasty 74f knee arthroplasty 113f Blood supply 3, 89 of patella 151f Bone cements 24 cuts 123 graft 76 loss 30, 151 quality 30 scan 35

stimulating 95 Bowing of femur 33

C Cement mixing technique 24f Cemented cup 19 hip 16, 16t posterior stabilized knee 118 stems 14 TKR 101 Cementless acetabular components 20 cup 20f hip 16, 16t stem 17, 17f, 18 TKR 100 total hip arthroplasty 7f Center of head 9 hip 33 patella 88f rotation of head 9 Ceramic implants 21t on ceramic hip 21, 21f on polyethylene hip 21f wear 12 Charnley’s cemented prosthesis 7f pillow 52f retractor 44f Circumcision of patella 123 Complete correction of flexion deformity 150f Complex primary total hip replacement 71 knee arthroplasty 146 Complications of bone cement 26 patellar resurfacing 103, 155 resurfacing 23f total hip arthroplasty 79 knee arthroplasty 153 CT scan 34

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Tips and Tricks in Hip and Knee Arthroplasty Cup 34 fixation 68 Current total hip arthroplasty 8 Custom made femoral components 19 Cutting synovium with cautery 122f

D Debulking of infrapatellar fat pad 124f Deep flexion 98 Deformity 94 Dislocation of femoral head 38f Distal centralizer in femoral cemented stem 25f femoral articular surface 91 femoral cut 130 medullary plug 25f Draped limb 42f Dysplasia 28 Dysplastic hip 76

E Early modern total hip arthroplasty 6 stage of total hip arthroplasty 6 Epicondylar axis 136 Excellent patelloplasty 103 Excise medial meniscus 146 Exposed knee joint 87f Exposure of acetabulum 54 Extension rods 106 External rotation deformity 73

F Faber deformity 73f Femoral component 14, 38, 40, 91 condyles 137f notch cut 136 rollback on tibia with flexion 92f stem 18, 34f, 68 Femur 3, 34, 78 Fixed bearing and mobile bearing knee 99t flexion deformity of knee 148 knee 99 Flat polyethylene surface 93 Fracture 155 neck of femur 24, 30 of proximal part of femur 31 Functions of bone cement 26

G Gap technique 136, 137 Gluteus maximus 4f, 5, 44f, 54 Greater trochanter 4f, 55f

H Hematoma formation 79 Heterotopic ossification 79 High   flex design 98, 98f, 99 flexion 98, 99 Hinged implants 106 knee prosthesis 107f Hip arthroplasty 6, 41, 41t, 78f center 9 joint 3 resurfacing 23 Hohmann’s retractor 4f, 54, 57f

I Ideal abduction angle 59f Impaction of morselized cancellous bone graft 61f Implants and bone cements 14 In-bed mobilization abduction 53f flexion 53f Inferior gemellus 5, 45f, 46f gluteal artery 3 Infrapatellar fat pad 85

J J curve 93 Joint line 120f replacements 95 sparing options 95 surface restoration 95 Judicious prophylaxis 102

K Kellgren stages of osteoarthritis of knee 95f Knee arthroplasty 90 joint 85, 86f Kohler line 29f

Index

L

P

Lateral collateral ligament 85 femoral condyle 131f Left side protrusio hip 72f Length of both limbs 65 Lesser trochanter 4f Level of greater trochanter 34f Ligamentum patellae 85 Limb length 31 discrepancy 32f, 81 Low molecular weight heparin 102f, 103f, 155f viscosity 24

Parts of bones forming hip joint 3 joint 85 quadratus femoris 46f Patellar clunk syndrome 155, 156 cut 137 tracking 151 Perioperative management of total hip arthroplasty 50 knee arthroplasty 111 Periprosthetic bone loss 12 fracture 155, 156 Pes anserinus tendon 146 Pie crusting technique 148 Piriformis tendon 5, 45f, 46f Pneumatic compression device 52f Polyethylene 93 wear 155 Posterior condylar axis 132 cruciate ligament 89 femoral condyle cut 131 osteophytes 112f Posteromedial corner 146 Postoperative skin traction 70 Primary total hip arthroplasty 54 knee arthroplasty 116 Prosthesis 34, 69 Prosthetic joint 9, 91, 91t Protrusio 28 Protrusion of medial wall of acetabulum 29f Psoriatic arthritis 49 Pulmonary embolism 80

M Magnetic resonance imaging 35 Measured resection technique 137 Medial cancellous calcar bone 64f collateral ligament 85, 88f, 134f tightness persists 146 Medium viscosity 24 Metal-on-metal total hip arthroplasty 22 Migration 38 Minimal invasive surgeries 48t Mobile knee 99, 100f Modern cementing techniques 26 Modular femoral stem 18

N Neck cut 54 shaft angle 33 Nerve injury 80 palsy 155 New high flex design 98 Normal hip 9 joint 91

O Obturator internus 5, 5f, 45f, 46f One finger test 103 Optimum bone cuts 116 Osteoarthritis 112f of knee joint 94 Osteotomy of neck 75, 75f

Q Q angle 89 Quadratus femoris 3, 5, 5f, 45f muscle 45f Quadriceps tendon, patella, ligamentum patellae 87f

R Ranawat technique 65f Reaming of acetabulum 57f Removal of anterior tibial osteophytes 125f

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Tips and Tricks in Hip and Knee Arthroplasty lateral femoral osteophytes 148f posterior osteophytes 149f part of medial meniscus 124f Residual flexion deformity 150f Resorption of calcar 32f Results of high flex designs 99 Resurfacing implants 22f Rule out hip infection 50

replacement in ankylosed hip 73 protrusio hip 71 Total knee arthroplasty 95, 96, 118 replacement 153 Transverse acetabular ligament 3, 4f Triathlon knee system 100 Trochanteric bursa 44f

S

U

Sciatic nerve 5, 5f, 45f, 71 proximity 29f Septic loosening of cemented hip stem 16f, 38f Seronegative disease 49 Severe unacceptable deformity 49 Skin necrosis and infection 103f staining/discoloration 102f Small contained bone defects 152f Solution stem 18f Stability of hip 64 Staging of osteoarthritis of knee 94 Standard total hip arthroplasty 8 Stiff hips 49 knee 151 Stimson method 81 Straight femoral stem 18 Superficial medial collateral ligament 146 Superior gemellus 5, 45f, 46f

Ultra high density 19 Uncemented porous coating 17 press-fit stems 18 Unicondylar knee 105t prosthesis 103 prosthesis in situ 104f Upridden greater trochanter 29

T Technique of primary total knee arthroplasty 116, 116t Tendinous portion of gluteus maximus 44f Thompson and Amp prostheses 7f Tibial articular surface 91 cut 123 surface 136 tubercle osteotomy 118 tuberosity 88f, 120f, 127f Total condylar prosthesis 90 Total hip arthroplasty 28

V Valgus knee 147 stem 37f Varus deformity 112f hips 11 knee 146 stem 37f Vascular injury 81 Vastus lateralis 4f Versatile modular and custom made hip system 19f V-Y plasty 118

W Well fixed cemented femoral stem 37f Wiring around diaphysis 36f Wound closure 70 inspection 51, 113

Z Zimmer knee 99