Nonarthroplastic Treatment of Hip Dysplasia in Adults

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1 ORTHOPAEDIC SURGERY BOARD REVIEW MANUAL PUBLISHING STAFF PRESIDENT, PUBLISHER Bruce M.White EXECUTIVE EDITOR Debra Dreger EDITOR Becky Krumm, ELS EDITORIAL ASSISTANT Deidre Yoder SPECIAL PROGRAMS DIRECTOR Barbara T.White, MBA PRODUCTION MANAGER Suzanne S. Banish PRODUCTION ASSISTANTS Tish Berchtold Klus Christie Grams ADVERTISING/PROJECT COORDINATOR Patricia Payne Castle NOTE FROM THE PUBLISHER: This peer-reviewed publication has been developed without involvement of or review by the American Board of Orthopaedic Surgery. Endorsed by the Association for Hospital Medical Education The Association for Hospital Medical Education endorses HOSPITAL PHYSICIAN for the purpose of presenting the latest developments in medical education as they affect residency programs and clinical hospital practice. Nonarthroplastic Treatment of Hip Dysplasia in Adults Series Editor and Contributing Author: Robert T. Trousdale, MD Assistant Professor of Orthopaedic Surgery Mayo Graduate School of Medicine Consultant, Department of Orthopaedic Surgery Mayo Clinic, Rochester, MN Contributing Author: Jeffrey P. Beckenbaugh, DO Resident in Orthopaedic Surgery Mayo Clinic, Rochester, MN Table of Contents Introduction Anatomy and Biomechanics Epidemiology Classification Clinical Evaluation Management Options The Bernese Periacetabular Osteotomy Conclusions References Cover Illustration by Vanessa Ray Copyright 2000, Turner White Communications, Inc., 125 Strafford Avenue, Suite 220, Wayne, PA , All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, mechanical, electronic, photocopying, recording, or otherwise, without the prior written permission of Turner White Communications, Inc. The editors are solely responsible for selecting content. Although the editors take great care to ensure accuracy, Turner White Communications, Inc., will not be liable for any errors of omission or inaccuracies in this publication. Opinions expressed are those of the authors and do not necessarily reflect those of Turner White Communications, Inc. Orthopaedic Surgery Volume 6, Part 1 1

2 ORTHOPAEDIC SURGERY BOARD REVIEW MANUAL Nonarthroplastic Treatment of Hip Dysplasia in Adults Series Editor and Contributing Author: Robert T. Trousdale, MD Assistant Professor of Orthopaedic Surgery Mayo Graduate School of Medicine Consultant, Department of Orthopaedic Surgery Mayo Clinic Rochester, MN Contributing Author: Jeffrey P. Beckenbaugh, DO Resident in Orthopaedic Surgery Mayo Clinic Rochester, MN I. INTRODUCTION Developmental dysplasia is a structural hip disorder that commonly leads to degenerative joint disease. Prior to the development of total joint arthroplasty, the treatment consisted primarily of conservative measures, femoral osteotomies, or pelvic osteotomies to correct joint incongruencies. Hip fusion was used as a last resort to control pain. The advent of total hip arthroplasty was a major step forward in the treatment of this disease, but there are limitations. Hip replacement surgery is very successful in the older, more sedentary patient population, but the results have been less satisfying in younger, more active patients. 1,2 Younger patients should still rely on conservative measures and osteotomies to help control pain. Various osteotomies have been developed to achieve proper joint mechanics in young patients with symptomatic hip dysplasia. One in particular, the Bernese periacetabular osteotomy (PAO), has shown promising outcomes and has become the procedure of choice at the authors institution for the treatment of developmental dysplasia of the hip in the absence of severe secondary degenerative changes. II. ANATOMY AND BIOMECHANICS A. Typical acetabular abnormalities 1. Poor anterior coverage of femoral head 2. Poor lateral coverage of femoral head 3. Reduction of acetabular depth 4. Excessive lateralization of the hip s center of rotation 5. Steep inclination of the sourcil (ie, the weightbearing surface of the hip) 6. Labral pathology 7. Rim fractures 8. A secondary acetabulum, which may develop if complete dislocation occurs B. Typical femoral abnormalities 1. Changes in shape of the femoral head a. May be enlarged in size b. May be reduced in size 2. Changes in shape of the femoral neck a. Decreased offset b. Increased anteversion c. Increased neck-shaft angle (coxa valga) 3. Proximally located greater trochanter 4. Shortened abductors 2 Hospital Physician Board Review Manual

3 5. Subluxation of the femoral head (occurs in varying degrees) C. Biomechanical changes 1. The contact area of the femoral head with the acetabulum is decreased, leading to increased contact force with the hip. 2. Increased pressures on the limited contact area result in early cartilaginous degeneration Lateralization of the hip s center of rotation increases the body weight lever arm and decreases the lever arm of the abductors, further increasing the forces placed on the hip. III. EPIDEMIOLOGY A. Incidence of hip dysplasia is 1:1000 births. Females predominate, with most studies showing a 2:1 to 3:1 ratio of women to men. B. Developmental dysplasia of the hip is one of the most common causes of hip degenerative joint disease Up to 48% of patients who require hip replacement for degenerative joint disease have been shown to have hip dysplasia as an underlying diagnosis Left untreated, hip dysplasia leads to osteoarthrosis in 25% to 50% of those affected by 50 years of age, 8,9 especially if the center edge angle (angle of Wiberg) is less than 20 degrees. IV. CLASSIFICATION A. Crowe classification for developmental dysplasia of the hip (based on the amount of femoral head subluxation) 1. Type I: less than 50% subluxation 2. Type II: 50% to 74% subluxation 3. Type III: 75% to 100% subluxation 4. Type IV: complete dislocation B. Tonnis classification of osteoarthrosis of the hip (based on radiographic assessment) 1. Grade 0: absence of osteoarthritis radiographically 2. Grade 1: sclerosis, mild joint-space loss, minimal osteophytes 3. Grade 2: small cysts, moderate joint-space loss 4. Grade 3: large cysts, moderate to complete joint-space loss V. CLINICAL EVALUATION A. Clinical presentation. The onset of symptoms varies depending on severity of dysplasia. 1. Patients most commonly complain of groin pain that occurs with activities. If no arthritis is present, the pain is probably secondary to subluxation of the joint. 2. If labral pathology is present, the patient may complain of catching and/or giving way. 3. If secondary degenerative changes are present, the patient may have arthritic pain. B. Physical examination 1. In patients with mild dysplasia, gait is often normal. 2. Range of motion (ROM) is often either normal or internal rotation is increased. 3. Leg length discrepancy secondary to subluxation may be present. 4. Apprehension test: extension and external rotation causes apprehension caused by a feeling of impending or actual subluxation. 5. Labral examination: adduction, internal rotation, and flexion cause stress on the labrum, which may elicit pain if pathology is present. C. Diagnostic imaging 1. Plain film radiographs a. Anteroposterior view of pelvis 1) Acetabular index angle (Tonnis angle) (Figure 1) a) Normal is 10 degrees ± 2 degrees b) Angle is increased in developmental dysplasia 2) Lateral center edge angle (Wiberg angle) (Figure 2) a) Normal is greater than 25 degrees b) Angle is decreased in developmental dysplasia 3) Lateralization. This can be easily measured as the distance from the medial femoral head to the ilioischial line. This distance is increased (in comparison to normal contralateral hip) in developmental dysplasia (Figure 3). 4) Cranialization. This is measured as the distance from the inferior edge of the femoral head to the most posteroinferior edge of the acetabulum. Orthopaedic Surgery Volume 6, Part 1 3

4 A I A V E C Figure 1. Radiographic measurement of the Tonnis angle, formed by drawing a line parallel to the interteardrop line (A), which intersects the medial edge of the weightbearing dome (sourcil) and a line connecting the edges of the sourcil (A ) on an anteroposterior radiograph. Normal is 10 degrees ± 2 degrees. Adapted from Trousdale RT:Acetabular osteotomy. In Reconstructive Surgery of the Joints, 2nd ed. Morrey BF, ed. New York: Churchill Livingstone, 1996:1309. By permission of Mayo Foundation. This distance is increased (in comparison to normal contralateral hip) in developmental dysplasia (Figure 3). b. False profile view. This is taken with the patient standing and angled 65 degrees from the film cassette (Figure 4). 1) This view documents the anterior coverage of the acetabulum over the femoral head. 2) Anterior center edge angle (Lesquesne angle) (Figure 5) a) Normal is greater than 20 degrees b) Angle is decreased in developmental dysplasia c. Functional views in abduction and adduction. These views demonstrate the congruency that can be obtained with repositioning of the femur. (Note that most patients with hip dysplasia cannot be adequately treated with femoral osteotomy alone because the deformity is chiefly on the acetabular side of the joint.) Figure 2. Anteroposterior pelvis radiographic measurement of the lateral center edge angle, or Wiberg angle (VCE). Normal is > 25 degrees. Adapted from Trousdale RT: Acetabular osteotomy. In Reconstructive Surgery of the Joints, 2nd ed. Morrey BF, ed. New York: Churchill Livingstone, 1996:1309. By permission of Mayo Foundation. 2. Computed tomographic scan with 3-dimensional reconstruction a. Useful when dealing with abnormal anatomy or previous pelvic surgery b. Helps map out available acetabular cartilage that could be used to cover the femoral head c. Helps in delineating positioning changes that will be necessary 3. Magnetic resonance imaging a. May be useful if attempting to identify labral pathology b. The use of intra-articular gadolinium increases the diagnostic value. VI. MANAGEMENT OPTIONS A. Conservative therapy 1. Nonsteroidal anti-inflammatory drugs, physical therapy, and activity modification may be helpful in alleviating symptoms. 2. Younger patients with more severe dysplasia (Wiberg angle < 20 degrees) should have 4 Hospital Physician Board Review Manual

5 surgery when symptoms warrant, prior to the development of arthritis. 3. In young patients, radiographic monitoring of joint space is necessary if conservative treatment is chosen. B. Operative management 1. Total hip arthroplasty a. Not a good choice for younger patients b. Consider if: 1) Patient is older than 60 years 2) Tonnis grade 3 degenerative joint disease is present 2. Hip arthrodesis. This option carries significant functional limitations: a. Loss of motion b. Limb shortening c. Increased energy expenditure with ambulation d. Increased incidence of low back pain and ipsilateral knee pain 3. Femoral osteotomy a. This procedure is rarely used alone because the usual site of deformity is on the acetabular side of the joint. b. This approach has marked limitations in its ability to obtain the necessary correction. c. It is useful as an adjunct procedure when coverage cannot be obtained by pelvic osteotomy alone. 4. Pelvic osteotomies/augmentations (Figure 6) a. Shelf procedures 1) These procedures do not allow for medialization. 2) A less desirable noncartilaginous surface is used for coverage. 3) These are useful only as salvage procedures. b. Chiari osteotomy. This is a medial displacement osteotomy with a single cut placed above the acetabulum in a curved fashion, with a 10- to 15-degree medial-tocranial path. 1) It allows for medialization of the hip s center of rotation, but does not allow for anterior correction. 2) Although coverage of the femoral head surface is increased, this added coverage is obtained from a fibrocartilaginous surface, which is less desirable than normal hyaline cartilage. 3) It requires exposure of both the inner and outer pelvic tables. Lat IL Cran PH Figure 3. Lateralization (Lat) is measured as the shortest distance between the medial border of the femoral head and the ilioischial line (IL). Cranialization (Cran) is measured as the shortest distance between the inferior border of the femoral head and the inferior edge of the posterior horn (PH). Adapted with permission from Siebenrock KA, Scholl E, Lottenbach M, Ganz R: Bernese periacetabular osteotomy. Clin Orthop June 1999:10. Film plate placed here Figure 4. A schematic drawing of patient positioning for obtaining a false profile radiograph.the patient is placed at a 65-degree angle from the film cassette.the beam is directed at a 90-degree angle from the film cassette.the hip being viewed is closest to the plate. Adapted from Trousdale RT: Acetabular osteotomy. In Reconstructive Surgery of the Joints, 2nd ed. Morrey BF, ed. New York: Churchill Livingstone, 1996:1308. By permission of Mayo Foundation. Orthopaedic Surgery Volume 6, Part 1 5

6 A V C A Figure 5. (A) Diagram of the measurement of the anterior center edge angle (VCA) on a false profile radiograph. Adapted from Trousdale RT: Acetabular osteotomy. In Reconstructive Surgery of the Joints, 2nd ed. Morrey BF, ed. New York: Churchill Livingstone, 1996:1309. By permission of Mayo Foundation. (B) False profile radiograph of a dysplastic hip showing the anterior center edge angle or Lesquesne angle. Normal is > 25 degrees; < 20 degrees indicates pathology. B c. Salter s single innominate osteotomy. Correction is limited in this procedure, especially anteriorly. d. Double innominate osteotomies (ie, Sutherland s, LeCoeur s, and Hopf s) 1) Correction is difficult and limited with these procedures. 2) Pelvic ring deformity results. 3) Postoperative external immobilization may be necessary. 4) Multiple incisions may be required. e. Triple innominate osteotomies (ie, Steel s, Carlioz s, and Tonnis ) 1) Ligament and muscle attachments can limit correction. 2) The pelvic ring is disrupted, increasing rehabilitation time. 3) Postoperative external immobilization may be necessary. 4) Multiple incisions may be required. f. Spherical osteotomies (ie, Eppright s, Wagner s, and Ninomiya s) 1) These procedures are technically difficult. 2) Inspection of the joint capsule may sacrifice the only remaining blood supply to the osteotomized fragment. g. Modified Bernese periacetabular osteotomy. This procedure has come to the forefront because of its balance between exposure, complications, and the ability to make the necessary correction. Technical details of this procedure are outlined in Section VII. 1) It allows for correction medially, laterally, and anteriorly. 2) The pelvic ring is not disrupted, allowing early mobilization. 3) The surgeon is able to directly inspect the joint for labral pathology without risking acetabular blood supply. 6 Hospital Physician Board Review Manual

7 VII. THE BERNESE PERIACETABULAR OSTEOTOMY A. Preparation 1. General anesthesia is used with no paralysis. 2. A cell saver should be used. 3. Intraoperative electromyographic monitoring can be utilized The entire limb is prepared. B. Special tools 1. A 30-degree 15-mm bifid curved osteotome 2. Straight 15-mm osteotome 3. Reverse curved retractors 4. Standard Schanz screw C. Approach options 1. Ilioinguinal a. This approach provides good exposure to the interior aspect of the pelvis. b. It carries a greater risk of femoral artery complications because of the medial retraction needed. 2. Direct anterior. Medial retraction may lead to neurovascular problems. 3. Double incision. This entails use of the Kocher-Langenbeck and modified Smith- Petersen approaches. a. Operative time is increased. b. It provides direct observation for the ischial osteotomy. c. It carries an increased risk of heterotopic ossification and devascularization of the acetabulum. 4. Modified Smith-Petersen a. A single incision is used. b. Abductors are not violated. c. It carries a low risk of devascularizing the acetabulum because the abductors can be left completely unviolated. d. Vascular risk is minimal. e. This approach is preferred by most surgeons f. Limitations 1) The first (ischial) osteotomy is blind. 2) It carries a higher incidence of lateral femoral cutaneous nerve injury. D. Surgical procedure using the modified Smith- Petersen approach Skin incision. The incision begins along the border of the iliac crest 6 to 8 cm proximal to the anterior-superior iliac spine (ASIS). It continues from the ASIS, down over the anteriorinferior iliac spine (AIIS), curving distally Salter Sutherland LeCoeur Hopf Steel Tonnis Carlioz Eppright Wagner Ninomiya Figure 6. Schematic diagrams of reorientation procedures. Depicted are Salter s single innominate osteotomy; Sutherland s, LeCouer s, and Hopf s double osteotomies;steel s triple osteotomy;carlioz s and Tonnis juxta-articular triple osteotomies;and Eppright s,wagner s,and Ninomiya s spherical/rotational osteotomies. Adapted with permission from Trousdale RT:Acetabular osteotomy.in Reconstructive Surgery of the Joints, 2nd ed. Morrey BF, ed. New York: Churchill Livingstone, 1996:1310. By permission of Mayo Foundation. thereafter, ending approximately 3 cm distal and anterior to the greater trochanter. 2. Superficial dissection a. The internervous plane between the tensor fascia lata (TFL) (superior gluteal nerve) and the sartorius (femoral nerve) is developed. Incising the deep fascia over the TFL muscle belly will help avoid Orthopaedic Surgery Volume 6, Part 1 7

8 injury to the lateral femoral cutaneous nerve (although occasionally the first lateral branch of this nerve will have to be sacrificed). b. Dissection is carried proximally to the ASIS and distally to the ascending branch of the lateral femoral circumflex artery, which supplies a portion of the TFL. c. The sartorius is released from the ASIS. 3. Deep dissection a. The hip is flexed and adducted. b. The inner table of the ilium is stripped subperiosteally down to the greater sciatic notch, allowing for placement of a retractor. c. The anterior iliacus capsular insertion is sharply removed and followed distally until the iliopsoas bursa is entered. d. The pubic bone is exposed and a singlespike, sharp Homan retractor is placed into the pubis to retract the iliopsoas tendon. e. The direct head of the rectus femoris is released from the AIIS. f. Using scissors, dissection is continued distally and medially to palpate the ischium and obturator foramen. g. Ganglions may be present and are an indication of labral disease. 4. Osteotomies (Figure 7) a. Ischial osteotomy 1) This osteotomy is blind. Image intensification may be useful. 2) The 30-degree bifid osteotome is used to score the ischium and then penetrate approximately 2 cm, leaving the posterolateral aspect of the ischium intact. 3) The angle of the osteotomy will be posterior and superior. b. Pubic osteotomy 1) This osteotomy must be placed medial enough to prevent entry into the joint. 2) The obturator nerve must be protected. 3) The osteotomy must be oblique to prevent migration of the iliopsoas tendon into the osteotomy site. c. Iliac osteotomy 1) This osteotomy usually begins just distal to the ASIS. Location can be confirmed with image intensification. 2) The initial cut of the ilium is made with a saw and continues to a point approximately 5 mm proximal to the pelvic brim. 3) At that point, an inferior turn of 110 to 120 degrees is made with the use of an osteotome. The osteotomy is continued for about 1 cm along the inner table of the pelvis, pointing toward the ischial spine. 4) A Schanz screw is placed in the AIIS, parallel to the inner pelvic brim, on top of the hip joint. 5) A laminar spreader is placed under tension in the superior iliac cut and a second laminar spreader is placed in the posterior inner table oblique cut, also under tension. 6) A controlled fracture is created by applying constant tension and twisting on the laminar spreaders while simultaneously pulling and turning the Schanz screw until the fracture line propagates from the iliac osteotomy to join the ischial osteotomy. d. When all three osteotomies are completed, the posterior column is left intact and the acetabular fragment should be completely free and mobile. 5. Positioning and securing the acetabular fragment. This is the most difficult part of the operation. a. The fragment is moved anteriorly and medially to provide improved lateral coverage of the femoral head. b. A threaded wire is placed from the ASIS into the acetabular fragment to hold the position. c. Intraoperative radiographs are obtained to confirm adequate anterior, posterior, and lateral coverage, as well as proper medialization and anteversion. d. When the position is satisfactory, the fragment is secured with 3 screws (Figures 7 and 8). e. The AIIS is trimmed and the bone is used as graft in the anterior iliac bone gap that has been created. f. The pubic osteotomy is reexamined to insure that the iliopsoas tendon has not slipped into the osteotomy site. E. Postoperative care 8 Hospital Physician Board Review Manual

9 Figure 7. Osteotomy locations and fixation for the periarticular osteotomy. Two 4.5-mm cortical screws are placed from the ilium into the acetabular fragment, then a third 4.5-mm cortical screw is placed from the acetabular fragment into the ilium. The screws should be countersunk. Adapted from Trousdale RT, Ganz R: Periacetabular osteotomy. In The Adult Hip. Callaghan JJ, Rosenberg AG, Rubash HE, eds. Philadelphia: Lippincott-Raven, 1998:792. By permission of Mayo Foundation. 1. Anticoagulation therapy a. Warfarin while the patient is in the hospital b. After discharge, 325 mg enteric-coated aspirin twice daily for 6 weeks 2. Routine drain removal 3. Out of bed on the second postoperative day 4. Partial weightbearing on the third postoperative day, to continue until 6 weeks 5. Cane ambulation allowed at 6 weeks, to continue until Trendelenburg gait disappears 6. Passive ROM exercises for the quadriceps are used for 6 weeks to protect the rectus femoris and sartorius repairs. At 6 weeks, active assisted ROM exercises are initiated. F. Results. Several studies have evaluated the results of PAO surgery. 1. Preliminary Bern report. In 1988, Ganz and colleagues 20 published a preliminary report on the Bern experience with the first 75 patients treated with PAO. a. Radiographic improvement. Vertical center edge and vertical center anterior angles improved significantly (to an average of 31 degrees and 26 degrees respectively). b. Complications. All clinically significant complications occurred during the first 18 operations. 1) Two intra-articular osteotomies occurred. Orthopaedic Surgery Volume 6, Part 1 9

10 Figure 8. Postoperative radiographs demonstrating an alternate method of fixation for the periarticular osteotomy, which uses three 4.5-mm cortical screws traveling from the ilium into the acetabular fragment. 2) Femoral nerve palsy occurred in 1 patient and resolved. 3) One nonunion occurred. 4) Ectopic bone formation occurred in 4 patients. (This was prior to the use of prophylactic indomethacin.) c. Importance of surgeon s experience with the procedure 1) As noted above, all major complications occurred in the first 18 patients. 2) Time spent in the operating room decreased 50% from the first cases to the last cases. 3) Blood loss was originally as much as 3000 ml, but was reduced to 800 ml on average in the last 10 cases. d. It was noted that the results were based on preliminary follow-up and more longterm study was needed. (This was done by Siebenrock and colleagues, 16 as described below.) 2. Long-term follow-up of Bern experience. In 1999, Siebenrock et al 16 published an 11.3-year follow-up report on 71 of the first 75 PAOs performed (95%), reported in the original article by Ganz and colleagues. 20 This constitutes the longest follow-up in evaluating results of the PAO. a. Fifty-eight cases (82%) had preservation of the hip joint at the last follow-up evaluation ( 10 years), with good to excellent results in 52 cases (73%), an average Harris hip score of 93, and an average d Aubigne hip score of b. Unfavorable outcome was significantly associated with: 1) Higher age of patient at the time of the procedure 2) Moderate to severe osteoarthrosis at the time of the procedure 3) Presence of a labral lesion 4) Less anterior coverage correction 5) A suboptimal postoperative acetabular index c. The outcome was good to excellent in 88% of the patients without a labral lesion who were classified as Tonnis grade 0 or 1. d. All radiographic measures showed significant improvement. 10 Hospital Physician Board Review Manual

11 e. There was a generalized trend toward loss of hip ROM in all directions; however, it was statistically significant in flexion only. 3. Results at other institutions. Others have reported on results of PAO at other institutions, with a follow-up period of approximately 3 to 4 years. 6,15,18,21,22 a. In general, radiographic results showed significant improvement by several measures, including lateral center edge angle, anterior center edge angle, acetabular index, medialization, cranialization, Shenton s line, and Tonnis grade. b. Clinical scores (d Aubigne, Harris, and Mayo hip scores) showed either improvement or no change. Relatively few patients experienced worsening of symptoms or function following the surgery. c. Hip ROM decreased slightly in all directions. 22 d. Recommendations regarding performing PAO in patients with Tonnis grade 3 osteoarthrosis are mixed. 1) Despite poorer outcomes compared to those with grade 1 or 2 osteoarthrosis, Trumble and colleagues 21 recommend PAO for Tonnis grade 3 patients who are young at presentation. 2) Trousdale and colleagues 18 recommend that PAO not be performed on patients with a preoperative rating of Tonnis grade 3 osteoarthrosis. e. Mayo et al 23 reported on 19 PAOs in 18 patients with prior surgery for hip dysplasia. No significant difference in outcomes was established (as compared to PAO patients without prior surgery). G. Complications 1. Heterotopic ossification a. Usually is asymptomatic b. Prophylaxis is not indicated (especially if the abductors are left intact) 2. Neuropraxia a. Lateral femoral cutaneous nerve injury 1) Associated with the ilioinguinal and modified Smith-Petersen approaches 2) Patients should be warned preoperatively of possible lateral thigh numbness. b. Femoral nerve injury may occur with the direct anterior approach. c. Sciatic nerve injury is a risk with all approaches. 3. Nonunion of an osteotomy site a. The pubic bone is the most common site of nonunion. 1) Pubic nonunion is thought to be secondary to marked displacement that occurs with correction. 2) It may be aggravated by an interposed iliopsoas tendon. b. Pubic nonunions are usually asymptomatic. 4. Femoral artery thrombosis a. This can be limb threatening if it is not recognized early. b. It is more common with the ilioinguinal approach. 5. Poor correction a. Inadequate coverage may lead to the development of degenerative joint disease. b. Excessive correction may lead to secondary impingement. c. Early postoperative weight bearing may result in rotation of the acetabular fragment. 6. Decreased ROM. Patients should be warned of this frequent complication prior to surgery. 7. Anterior femoral impingement (Myers et al). 24 This complication is thought to be secondary to an abnormal head-to-neck relationship of the dysplastic proximal femur. It was treated successfully with anterior femoral neck resection osteoplasty in 5 patients, with good immediate postoperative results. 8. Intra-articular osteotomy. This is a technical complication whose occurrence is heavily dependent on the surgeon s learning curve. 9. Deep venous thrombosis VIII. CONCLUSIONS A. PAO is an excellent procedure for the treatment of the dysplastic hip, providing good to excellent clinical results in carefully selected patients. B. The careful selection of patients is important to the success of the procedure. 1. Early intervention may prove to be key to improved outcome studies have shown that PAOs performed in earlier clinical stages (ie, prior to marked osteoarthritis) have better success rates. 2. Patient selection is limited by the fact that Orthopaedic Surgery Volume 6, Part 1 11

12 there are no satisfactory alternative treatments available for young patients with osteoarthrosis secondary to hip dysplasia. C. PAO is a technically demanding procedure. 1. The surgeon should be dedicated to performing this procedure on a regular basis. 2. The learning curve is significant and complications decrease sharply with increased experience. D. Patients should fully understand the limitations of the procedure: 1. They may lose some hip ROM. 2. They may have some lateral thigh numbness. 3. Functional outcomes may be limited if the stage of osteoarthrosis is advanced. REFERENCES 1. Berry DJ, Cabanela ME: Primary uncemented total hip arthroplasty in patients less than 40 years of age [Abstract]. Orthop Trans 1993;17: Chandler HP, Reineck FT, Wixson RL, McCarthy JC: Total hip replacement in patients younger than thirty years old: a five-year follow-up study. J Bone Joint Surg [Am] 1981;63: Hadley NA, Brown TD, Weinstein SL: The effects of contact pressure elevations and aseptic necrosis on the longterm outcome of congenital hip dislocation. J Orthop Res 1990;8: Maxian TA, Brown TD, Weinstein SL: Chronic stress tolerance levels for human articular cartilage: two nonuniform contact models applied to long-term follow-up of CDH. J Biomech 1995;28: Pauwels F: Osteoarthritis. In Biomechanics of the Normal and Diseased Hip: Theoretical Foundation, Technique, and Results of Treatment. Pauwels F, ed. New York: Springer- Verlag, 1976: Matta JM, Stover MD, Siebenrock K: Periacetabular osteotomy through the Smith-Petersen approach. Clin Orthop June 1999: Stullberg SD, Harris WH: Acetabular dysplasia and development of osteoarthrosis of the hip. The Hip: Proceedings of the Second Open Scientific Meeting of the Hip Society. St. Louis: CV Mosby, 1995: Cooperman DR, Wallensten R, Stulberg SD: Postreduction avascular necrosis in congenital dislocation of the hip. J Bone Joint Surg [Am] 1980;62: Cooperman DR, Wallensten R, Stulberg SD: Acetabular dysplasia in the adult. Clin Orthop May 1983: McGrory BJ, Trousdale RT: Sterile electromyographic monitoring during hip and pelvis surgery. Orthop Rev 1994;23: Davey JP, Santore RF: Complications of periacetabular osteotomy. Clin Orthop June 1999: Hussell JG, Mast JW, Mayo KA, et al: A comparison of different surgical approaches for the periacetabular osteotomy. Clin Orthop June 1999: Hussell JG, Rodriguez JA, Ganz R: Technical complications of the Bernese periacetabular osteotomy. Clin Orthop June 1999: McGrory BJ, Trousdale RT, Cabanela ME, Ganz R: Bernese periacetabular osteotomy: surgical technique. Journal of Orthopedic Technique 1993;1: Murphy SB, Millis MB, Hall JE: Surgical correction of acetabular dysplasia in the adult: a Boston experience. Clin Orthop June 1999: Siebenrock KA, Scholl E, Lottenbach M, Ganz R: Bernese periacetabular osteotomy. Clin Orthop June 1999: Trousdale RT: Acetabular osteotomy. In Reconstructive Surgery of the Joints, 2nd ed. Morrey BF, ed. New York: Churchill Livingstone, 1996: Trousdale RT, Ekkernkamp A, Ganz R, Wallrichs SL: Periacetabular and intertrochanteric osteotomy for the treatment of osteoarthrosis in dysplastic hips. J Bone Joint Surg [Am] 1995;77: Trousdale RT, Ganz R: Periacetabular osteotomy. In The Adult Hip. Callaghan JJ, Rosenberg AG, Rubash HE, eds. Philadelphia: Lippincott-Raven, 1998: Ganz R, Klaue K, Vinh TS, Mast JW: A new periacetabular osteotomy for the treatment of hip dysplasias: technique and preliminary results. Clin Orthop July 1988: Trumble SJ, Mayo KA, Mast JW: The periacetabular osteotomy: minimum 2 year follow-up in more than 100 hips. Clin Orthop June 1999: Crockarell J Jr, Trousdale RT, Cabanela ME, Berry DJ: Early experience and results with the periacetabular osteotomy: the Mayo Clinic experience. Clin Orthop June 1999: Mayo KA, Trumble SJ, Mast JW: Results of periacetabular osteotomy in patients with previous surgery for hip dysplasia. Clin Orthop June 1999: Myers SR, Eijer H, Ganz R: Anterior femoroacetabular impingement after periacetabular osteotomy. Clin Orthop June 1999: Copyright 2000 by Turner White Communications Inc., Wayne, PA. All rights reserved. 12 Hospital Physician Board Review Manual