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THE HIP SOCIETY |
MEETING OF THE HIP SOCIETY Thirty-Sixth Open Meeting of the Hip Society The Fourteenth Combined Open Meeting Hip Society and AAHKS San Francisco, CA Saturday, March 8, 2008 PROGRAM CHAIRMAN Arlen D. Hanssen, M.D. CONTENTS: COURSE OBJECTIVES: The objectives of the Open Meeting of the Hip Society are to provide up-to-date information on the treatment of hip problems including arthroplasty and non-arthroplasty options and surgical techniques. COURSE DESCRIPTION: This course is divided into twelve symposia covering femoroacetabular impingement, avoiding prosthetic impingement, hip resurfacing, surgical aspects of primary THR, venous thromboembolism prophylaxis, acetabular component positioning, and femoral revision techniques. There will also be a presentation of the Hip Society Award papers and a special Presidential Guest Speaker. INTENDED AUDIENCE: The intended audience is orthopedic surgeons and orthopaedic residents. 8:00 a.m. Welcome Lawrence D. Dorr, M.D. - President Inglewood, CA SYMPOSIUM I: FEMOROACETABULAR IMPINGEMENT Moderator: Miguel E. Cabanela, M.D.Rochester, MN 8:05 a.m. Hip Joint Impingement Robert Trousdale, M.D. Rochester, MN 8:14 a.m. Pathoanatomy and Histomorphological Features of Femoroacetabular Impingement (FAI) Reinhold Ganz, M.D. Zurich, Schweiz 8:23 a.m. Femoroacetabular Impingement: Arthroscopy/Limited Anterior Approach John C. Clohisy, M.D. St. Louis, MO 8:32 a.m. Surgical Dislocation and Osteochondroplasty for FAI Christopher L. Peters, M.D. Salt Lake City, UT 8:41 a.m. Acetabular Retroversion: Rotational Osteotomy vs. Rim Trimming Richard Santore, M.D. San Diego, CA 8:50 a.m. DISCUSSION SYMPOSIUM II: AVOIDING PROSTHETIC IMPINGEMENT Moderator: Steven J. MacDonald, M.D.London, Ontario 9:06 a.m. Avoiding Prosthetic Impingement - Defining The Problem Cecil H. Rorabeck, M.D. London, Ontario 9:15 a.m. Combined Anteversion Test, Leg Length And OffsetChitranjan S. Ranawat, M.D. New York, NY 9:24 a.m. Using Crosslinked PE with Big Femoral Heads Bas Masri, M.D. Vancouver, BC 9:33 a.m. Avoiding Prosthetic Impingement by Using Large MOM Articulations Thomas Parker Vail, M.D. San Francisco, CA 9:42 a.m. Femoral Design and Impingement Robert B. Bourne, M.D. London, Ontario 9:51 a.m. DISCUSSION 10:11 a.m. BREAK SYMPOSIUM III: HIP RESURFACING DEBATE Moderator: Thomas S. Thornhill, M.D.Boston, MA 10:26 a.m. Support: Derek J. McMinn, M.D. Birmingham, United Kingdom 10:35 a.m. Why I Do Not Do Resurfacing-Yet William N. Capello, M.D. Indianapolis, IN 10:44 a.m. REBUTTAL DISCUSSION SYMPOSIUM IV: HIP RESURFACING Moderator: Merrill Ritter, M.D.Indianapolis, IN 10:51 a.m. Patient Selection for Total Hip Resurfacing Robert Barrack, M.D. St. Louis, MO 10:59 a.m. Principles of Correct Technique Michael Mont, M.D. Baltimore, MD 11:07 a.m. Is Impingement A Problem After Hip Resurfacing? Harlan C. Amstutz, M.D. Los Angeles, CA 11:15 a.m. Comparison of Resurfacing and Conventional Results Michael Tanzer, M.D. Montreal, Quebec 11:23 a.m. DISCUSSION SYMPOSIUM V: PRESIDENTIAL GUEST ADDRESS 11:31 a.m. Concepts and Results of Metal-on-Metal Surface ReplacementDerek J. McMinn, M.D.Birmingham, United Kingdom SYMPOSIUM VI: LIFETIME ACHIEVEMENT AWARD 12:00 p.m. LUNCH 1:00 p.m. SYMPOSIUM VII: CLOSED HIP MEETING ABSTRACTS Arlen D. Hanssen, M.D.Rochester, MN SYMPOSIUM VIII: HOW I DO A PRIMARY THRModerator: Daniel J. Berry, M.D.Rochester, MN 1:11 p.m. Panel Discussion: Joseph C. McCarthy Jr, M.D., William Hozack, M.D., William Maloney, M.D., Kevin L. Garvin, M.D., Douglas A. Dennis, M.D., Benjamin E. Bierbaum, M.D. SYMPOSIUM IX: HIP SOCIETY AWARDS Moderator: William Healy, M.D.Burlington, MA 1:35 p.m. The John Charnley Award A Comparison of Three Total Hip Arthroplasty Bearing Surfaces: A Randomized Trial C. Anderson Engh, Jr., M.D. Alexandria, VA 1:44 p.m. The Frank Stinchfield Award Variation in Postoperative Pelvic Tilt May Confound the Accuracy of Hip Navigation Systems Sebastien Parratte, M.D. 1:53 p.m. The Otto Aufranc Award Cement Penetration In Hip Resurfacing: Femoral Component Design And Cementation Technique Paul E. Beaulé, M.D. SYMPOSIUM X: VENOUS THROMBOEMBOLISM DEBATE CHEST PHYSICIAN GUIDELINES: Moderator: Cecil H. Rorabeck, M.D. London, Ontario 2:04 p.m. ACCP Guidelines: In Opposition Thomas P. Sculco, M.D. New York, NY 2:12 p.m. Chest Physicians Guidelines: Approve with Reservations Jay R. Lieberman, M.D. Farmington, CT 2:20 p.m. REBUTTAL DISCUSSION SYMPOSIUM XI: VENOUS THROMBOEMBOLISM PROPHYLAXIS Moderator: Norman Johanson, M.D. Philadelphia, PA 2:26 p.m. The Position of the AAOS on Thromboembolism Prophylaxis Paul Lachiewicz, M.D. Chapel Hill, NC 2:34 p.m. Clinical Outcomes with Chemoprophylaxis Vincent Pellegrini, M.D. Baltimore, MD 2:42 p.m. Multimodal Prophylaxis and Aspirin Eduardo A. Salvati, M.D. New York, NY 2:50 p.m. DISCUSSION 3:05 p.m. BREAK SYMPOSIUM XII: ACETABULAR COMPONENT POSITIONING TECHNIQUESModerator: Paul M. Pellicci, M.D. New York, NY 3:21 p.m. The Transverse Acetabular Ligament as a Guide to Anteversion in Total Hip Arthroplasty Mark W. Pagnano, M.D. Rochester, MN 3:29 p.m. Anatomic Landmarks for Acetabular Positioning: The Sciatic Notch & Acetabular Anteversion James D'Antonio, M.D. Sewickley, PA 3:37 p.m. Acetabular Orientation: Anterolateral Approach in the Supine Position Richard Rothman, M.D. Philadelphia, PA 3:45 p.m. Combined Anteversion Technique for Cup Position Lawrence D. Dorr, M.D. Inglewood, CA 3:53 p.m. Cemented Liners Into Shells John J. Callaghan, M.D. Iowa City, IA 4:01 p.m. DISCUSSION SYMPOSIUM XIII: VIDEO TECHNIQUES REVISION FEMORAL RECONSTRUCTION Moderator: Adolph V. Lombardi Jr., M.D. New Albany, OH 4:20 p.m. Revision of Surface Replacement Michael Mont, M.D. Baltimore, MD 4:27 p.m. Monoblock Femoral Revision Thomas Fehring, M.D. Charlotte, NC 4:35 p.m. Modular Femoral Revision Wayne Paprosky, M.D. Winfield, IL 4:42 p.m. Revisions of Patulous Intramedullary Canal David G. Lewallen, M.D. Rochester, MN 4:50 p.m. Revision of Absent Proximal Femur Alan E. Gross, M.D. Toronto, Ontario 4:57 p.m. Two-Stage Management of Infection After Hip Replacement Using an Interval Antibiotic Spacer Clive P. Duncan, M.D. Vancouver, BC 5:05 p.m. DISCUSSION 5:20 p.m. ADJOURN
8:14 a.m. Pathoanatomy and Histomorphological Features of Femoroacetabular Impingement (FAI) Reinhold Ganz, M.D. The key recognition of FAI is that even minor abnormalities of the proximal end of the femur but also abnormal orientation and depth of the acetabulum can become difficult for motion and may lead to impingement within the well constraint hip joint 1. Internal rotation in flexion is the most critical movement. G.Preiser speculated already in 1911 about reduced internal rotation and later development of osteoarthritis 2, however the impingement concept was only formulated a decade ago 3. High speed movement is more destructive than impingement with slow motion. Morphological abnormalities are not necessarily visible on standard ap-radiographs of the hip and pelvis. Lateral views more often reveal a nonspherical extension of the antero-lateral head contour. Although a silent slip produces a similar impingement with its prominent metaphysis, the majority of such nonspherical extensions is covered with hyaline cartilage and therefore part of the epiphysis 4. The abutment from femoral causes ( idiopathic, SCFE, posttraumatic retrotilt of the head, head deformation from Perthes disease or AVN) is called cam impingement. The out of round sector of the head or the head-neck junction is jammed into the socket and leads to outside-in abrasion or even avulsion of the joint cartilage, while the labrum in the first instance remains intact. With time middle section and basis of the disconnected labrum degenerate, while the tip region continues to keeps its normal texture over a long period 5, allowing its use for refixation 6. Successful refixation has been proven repeatedly by MR arthrography and by arthroscopy. The cartilage covering the spherical part of the femoral head remains intact over a long time, while the cartilage of the nonsperical zone shows increasing signs of damage. The area of maximum impingement is in about 30% of the more chronic cases characterized by an impingement cyst 7, which often has been erroneously interpreted as osteoid osteoma. Impingement from acetabular causes ( idiopathic and other retroversion, coxa profunda , protrusio) is called pincer impingement .Idiopathic retroversion is less an acetabular and more a pelvic pathomorphology 8,9. Pincer impingement is produced by a linear impact between the head-neck junction and the area of overcoverage of the acetabular rim. The squeezing of the labrum and the fact that the labrum contains nerve endings 10 , may explain why this, mainly female type of impingement, is clearly more painful than the cam impingement. With chronic impingement the labrum shows degeneration and intrasubstance ganglion formation .The chronic mechanical irritation initiates bony rim apposition , which by continuous growing, leads to expansion and thinning of the overlying labrum until the involved sector shows a complete bony rim; as such it increases the overcoverage and therefore the impingement. The bony rim is rarely the result of an intra substance ossification of the labrum. Although more painful, pincer impingement leads to less and slower destruction of the joint cartilage , ending rather late in the full picture of typical posteromedial osteoarthritis of the hip. 1. Ganz R, Leunig M, Leunig-Ganz K, Harris WH: The etiology of osteoarthritis of the hip. An integrated mechanical concept. Clin Orthop Relat Res. in press 2. Preiser G.: Statische Gelenkerkrankungen. Enke, Stuttgart 1911,p.78 3. Ganz R, Parvizi J, Beck M, Leunig M, Nötzli H, Siebenrock KA: Femoroacetabular impingement: a cause for osteoarthritis of the hip. Clin Orthop Relat Res. 2003; 417: 112-120. 4. Wagner S, Hofstetter W, Chiquet M, Mainil-Varlet P, Stauffer E, Ganz R, Siebenrock KA: Early osteoarthritic changes of human femoral head cartilage subsequent to Femoroacetabular impingement. Osteoarthritis Cartilage. 2003; 11: 508-518. 5. Ito K, Leunig M, Ganz R: Histopathologic features of the acetabular labrum in femoroacetabular impingement. Clin Orthop Relat Res. 2004;429:262-271 6. Espinosa N, Rothenfluh DA, Beck M, Ganz R, Leunig M: Treatment of femoro-acetabular impingement: Preliminary results of labral refixation. J Bone Joint Surg Am. 2006; 88:925-935. 7. Leunig M, Beck M, Kalhor M, Kim YJ, Werlen S, Ganz R: Fibrocystic changes at anterosuperior femoral neck: Prevalence in hips with femoroacetabular impingement. Radiology. 2005; 236: 237-246 8. Jamali AA, Mladenov K, Meyer DC,Martinez A, Beck M, Ganz R, Leunig M: Antero-posterior pelvic radiographs to assess acetabular retroversion: High validity of the „ cross-over-sign“. ; JOR 2007; DOI 10.1002/jor. 20380 9. Kalberer F, Sierra RJ, Madan SS, Ganz R, Leunig M: Ischial spine projection into the pelvis. A new sign for acetabular retroversion. Clin Orthop Relat Res 2007; DOI 10.1007/ s 11999-007-0058-6 10. Kim YT,Azuma H: The nerve endings of the acetabular labrum. Clin Orthop Relat Res. 1995; 320: 176-181 8:23 a.m. Femoroacetabular Impingement: Arthroscopy/Limited Anterior Approach John C. Clohisy, M.D. I. Objectives Discuss the rationale, patient selection criteria, and surgical techniques of hip arthroscopy and limited open osteochondroplasty for the treatment of anterior femoroacetabular impingement disorders. II. Introduction Structural hip disease is recognized as a cause of early hip dysfunction, articular degeneration and eventual secondary osteoarthritis. With heightened awareness of femoroacetabular impingement disorders, early diagnosis and joint preservation surgical treatment is becoming more commonplace. Various surgical techniques have evolved for the treatment of femoroacetabular impingement, and include periacetabular osteotomy, surgical hip dislocation, arthroscopy with limited open osteochondroplasty and arthroscopic techniques alone. Surgical treatment is focused upon comprehensive deformity correction and concurrent management of intraarticular disease. The optimal surgical technique may vary depending upon the distinct pattern of impingement disease and the expertise and technical preferences of the surgeon. In this presentation, the rationale, patient selection criteria, and surgical techniques of hip arthroscopy and limited anterior exposure for the treatment of femoroacetabular impingement will be discussed. III. Procedure Rationale: Hip arthroscopy/limited open osteochondroplasty Disease Characteristics - femoral deformities (aspherical femoral head, reduced head-neck offset) as the major source of repetitive impingement - acetabular deformities- overcoverage due to retroversion, profunda, protrusio - articular cartilage delamination/chondromalacia - labral tear/detachment - posterior articular disease/osteophyte - progressive secondary OA Patient Selection Criteria Indications - symptomatic AFI, patients < 55 years (physiologic) - focal disease patterns best candidates for less-invasive techniques - no or mild secondary OA (Tonnis I) Contraindications - age > 55 years (physiologic) - advanced DJD - circumferential or complex disease patterns (relative contraindication) - severe obesity - disease pattern better suited for open procedure (surgeon dependent) IV. Surgical Technique Hip arthroscopy/limited open osteochondroplasty for cam impingement Preoperative Planning - understand the osseous deformities and associated intraarticular disease - plan osseous and soft tissue aspects of the procedure - know limitations of the different surgical techniques Hip Arthroscopy - supine or lateral position, traction to access joint - anterior, anterolateral, posterolateral, and accessory portals - labrum, acetabular articular cartilage, synovitis, counter lesion - partial labral resection leaving stable labral remnant or labral repair if healthy tissue - partial synovectomy - chondroplasty/microfracture as needed -acetabular rim trimming or femoral osteochondroplasty if scope only technique Limited open osteochondroplasty (traction released, leg free) - limited Smith-Peterson/Heuter interval - incision straight distal from ASIS or translate 2-3cm lateral - develop TFL/Sartorius interval - rectus release optional (commonly release reflected head) - expose anterior hip capsule -capsulotomy and inspection of femoral head-neck junction and acetabular rim - osteochondroplasty with anteromedial head-neck junction, articular cartilage discoloration and “trough” at head or head-neck junction as “guides” to resection - after initial resection assess impingement with visualization, palpation in flexion/internal rotation - also assess fluoroscopically (“frog lateral”/Dunn views helpful to visualize anterolateral head-neck junction”) - capsular closure V. Advantages/Disadvantagesof combined hip scope and limited open osteochondroplasty Advantages - precise (arthroscopic) management of intraarticular disease - joint assessment prior to open procedure -excellent visualization of anterolateral head-neck junction for recontouring - capsular closure (not resection) - technically straightforward - technically time efficient - less invasive than surgical dislocation (avoid troch osteotomy/dislocation) - technically feasible for suboptimal candidates (obese, DJD, muscular) - surgeon “learns” the disease characteristics - “bridge” from open to arthroscopic treatment - early clinical results favorable Disadvantages - access limited to anterolateral head-neck junction - most appropriate for cam impingement - acetabular rim osteoplasty technically difficult - LFC nerve at risk -inadequate for severe/complex deformities, - early clinical follow-up only - more “invasive” than arthroscopic techniques Selected References 1. Beck M, Leunig M, Parvizi J, Boutier V, Wyss D, Ganz R. Anterior femoroacetabular impingement: part II. Midterm results of surgical treatment. Clin Orthop Relat Res 2004 (418):67-73. 2. Burnett RS, Della Rocca GJ, Prather H, Curry M, Maloney WJ, Clohisy JC. Clinical presentation of patients with tears of the acetabular labrum. J Bone Joint Surg Am 2006;88(7):1448-57. 3. Clohisy JC, Keeney JA, Schoenecker PL. Preliminary assessment and treatment guidelines for hip disorders in young adults. Clin Orthop Relat Res 2005;441:168-79. 4. Clohisy JC, McClure JT. Treatment of anterior femoroacetabular impingement with combined hip arthroscopy and limited anterior decompression. Iowa Orthop J 2005:25:164-71. 5. Clohisy JC, Zebala L, Hinkle S, McClure T, Robison JF. Combined Hip Arthroscopy and Limited Open Osteochondroplasty for Treating Impingement Disease. Annual Meeting of the American Academy of Orthopaedic Surgeons, San Diego, CA, February, 2007. 6. Ganz R, Gill TJ, Gautier E, Ganz K, Krugel N, Berlemann U. Surgical dislocation of the adult hip a technique with full access to the femoral head and acetabulum without the risk of avascular necrosis. J Bone Joint Surg Br 2001;83(8):1119-24. 7. Ganz R, Parvizi J, Beck M, Leunig M, Notzli H, Siebenrock KA. Femoroacetabular impingement: a cause for osteoarthritis of the hip. Clin Orthop Relat Res 2003(417):112-20 8. Guanche CA, Bare AA. Arthroscopic treatment of femoroacetabular impingement. Arthroscopy 2006;22(1):95-106. 9. Lavigne M, Parvizi J, Beck M, Siebenrock KA, Ganz R, Leunig M. Anterior Femoroacetabular impingement: part I. Techniques of joint preserving surgery. Clin Orthop Relat Res 2004(418):61-6. 10. McCarthy JC, Noble PC, Schuck MR, Wright J, Lee J. The Otto E. Aufranc Award:The role of labral lesions to development of early degenerative hip disease. Clin Orthop Relat Res 2001(393):25-37. 11. Philippon MJ, et al. Arthroscopic Management of Femoroacetabular Impingement AJSM, 2007. 8:32 a.m. Surgical Dislocation and Osteochondroplasty for FAI Christopher L. Peters, M.D. Introduction: Femoro-acetabular impingement (FAI) has been shown to cause labral and/or articular cartilage damage and ultimately lead to osteoarthritis of the hip. Surgical treatment of FAI is directed at alleviating femoral abutment against the acetabular rim with improvement of head-neck offset or acetabular rim resection. Labrum and articular cartilage lesions can be addressed with repair and/or resection. Surgical dislocation and osteochondroplasty (SDO) has proven to be a safe and effective approach to accomplish treatment of lesions associated with FAI. Surgical Technique: SDO is performed utilizing a lateral incision with greater trochanteric flip osteotomy with the patient in the lateral position. A Z-shaped anterior capsulotomy is performed and the femoral head is dislocated anteriorly. The femoral head-neck area is assessed for reduction in femoral head-neck offset and articular cartilage damage. Loss of the normal concave transition between the normally spherical femoral articular surface and the more elliptical femoral neck, with chondro-osseous overgrowth, is debrided with a chisel, osteotome and high-speed rotating burr. Full exposure of the acetabulum allows an assessment of labral and articular cartilage damage. Delaminated or damaged articular cartilage subjacent to a normal capsular labral margin is frequently encountered. Damaged articular cartilage is addressed with resection and labral advancement. Isolated or combined labral lesions or ossified labrum can be treated with repair or resection. The approach is utilitarian and can be used for relative femoral neck lengthening, femoral neck osteotomy, treatment of femoral head fracture, osteonecrosis, and resurfacing. Results: From 2001-2007 95 surgical dislocations were performed for a variety of indications. Of 80 hips performed for treatment of FAI (average age 28, range 15-50), 75 have survived at average follow-up of 2.5 years. The average surgical time was 105 minutes (range 65-150), average EBL was 344 cc, and average hospital stay was 2 days (range 1-3 days). The average time to unsupported ambulation was 6 weeks. The Harris hip score improved from 70 to 87 post-operatively. There have been no major perioperative complications or trochanteric nonunions. We continue to utilize this approach commonly for the treatment of young adults with hip pain due to FAI and other conditions. 8:41 a.m. Acetabular Retroversion: Rotational Osteotomy vs. Rim Trimming Richard Santore, M.D. Retroversion of the acetabulum is defined in reference to the sagittal plane as a posterolaterally directed opening at its proximal extent.16 It has been described in hip dysplasia,6,10,12-14,16 other childhood hip disorders,4-6,22 post-traumatic deformity,3 and in otherwise normal appearing hips.16,17 Since first being described by Tönnis in 19841, it has been increasingly recognized as a cause of hip pain on the basis of femoro-acetabular impingement (FAI) and has been linked to osteoarthritis of the hip.2,6-8,11,16,18 It has also been linked to acetabular labral tears as part of the spectrum of FAI.7,9,21 The anatomic variation in cases of acetabular retroversion fall along a spectrum and this has caused some confusion in the literature.20 The analysis of retroversion on a single AP radiograph of the pelvis is subject to the influences of rotation and lordosis of the pelvis on the relative positions of the anterior and posterior acetabular margins. It has not been scientifically established that all retroverted hips are posterolaterally deficient. Some retroverted hips have adequate posterolateral femoral head coverage while others are deficient posterolaterally.17 Torsion and deficiency are separate considerations. Every case is unique and treatment must be individualized according to the anatomy. Redirectional acetabular osteotomy is more likely to benefit those patients with associated lateral coverage deficiency dysplasia. Rim trimming procedures are better for otherwise normal hips that happen to be retroverted or hips with coxa profunda or protrusio17. Understanding the changes on the femoral side also weigh in on the surgical decision, as cam lesions may co-exist15,17 as well as abnormalities in femoral version.18,19 Both surgical dislocation for rim trimming and redirectional osteotomy are major surgical procedures and should not be undertaken without respect for the magnitude of the surgery, the length of recovery and the potential for complications. The concept of retroversion has potential implications in the arthroplasty population, both with regard to component positioning and anterior impingement. Future research will be needed to sort out how best to modify component positioning in the subgroup of THR patients with underlying acetabular retroversion.6,8 1. Banks, K. P., and Grayson, D. E.: Acetabular retroversion as a rare cause of chronic hip pain: recognition of the "figure-eight" sign. Skeletal Radiol, 36 Suppl 1: S108-11, 2007. 2. Beck, M.; Kalhor, M.; Leunig, M.; and Ganz, R.: Hip morphology influences the pattern of damage to the acetabular cartilage: femoroacetabular impingement as a cause of early osteoarthritis of the hip. J Bone Joint Surg Br, 87(7): 1012-8, 2005. 3. Dora, C.; Zurbach, J.; Hersche, O.; and Ganz, R.: Pathomorphologic characteristics of posttraumatic acetabular dysplasia. J Orthop Trauma, 14(7): 483-9, 2000. 4. Eijer, H.: Towards a better understanding of the aetiology of Legg-Calve-Perthes' disease: acetabular retroversion may cause abnormal loading of dorsal femoral head-neck junction with restricted blood supply to the femoral epiphysis. Med Hypotheses, 68(5): 995-7, 2007. 5. Eijer, H.; Berg, R. P.; Haverkamp, D.; and Pecasse, G. A.: Hip deformity in symptomatic adult Perthes' disease. Acta Orthop Belg, 72(6): 683-92, 2006. 6. Ezoe, M.; Naito, M.; and Inoue, T.: The prevalence of acetabular retroversion among various disorders of the hip. J Bone Joint Surg Am, 88(2): 372-9, 2006. 7. Ganz, R.; Parvizi, J.; Beck, M.; Leunig, M.; Notzli, H.; and Siebenrock, K. A.: Femoroacetabular impingement: a cause for osteoarthritis of the hip. Clin Orthop Relat Res, (417): 11220, 2003. 8. Giori, N. J., and Trousdale, R. T.: Acetabular retroversion is associated with osteoarthritis of the hip. Clin Orthop Relat Res, (417): 263-9, 2003. 9. Guevara, C. J.; Pietrobon, R.; Carothers, J. T.; Olson, S. A.; and Vail, T. P.: Comprehensive morphologic evaluation of the hip in patients with symptomatic labral tear. Clin Orthop Relat Res, 453: 277-85, 2006. 10. Kim, S. S.; Frick, S. L.; and Wenger, D. R.: Anteversion of the acetabulum in developmental dysplasia of the hip: analysis with computed tomography. J Pediatr Orthop, 19(4): 438-42, 1999. 11. Kim, W. Y.; Hutchinson, C. E.; Andrew, J. G.; and Allen, P. D.: The relationship between acetabular retroversion and osteoarthritis of the hip. J Bone Joint Surg Br, 88(6): 7279, 2006. 12. Li, P. L., and Ganz, R.: Morphologic features of congenital acetabular dysplasia: one in six is retroverted. Clin Orthop Relat Res, (416): 245-53, 2003. 13. Mast, J. W.; Brunner, R. L.; and Zebrack, J.: Recognizing acetabular version in the radiographic presentation of hip dysplasia. Clin Orthop Relat Res, (418): 48-53, 2004. 14. Murphy, S. B.; Kijewski, P. K.; Millis, M. B.; and Harless, A.: Acetabular dysplasia in the adolescent and young adult. Clin Orthop Relat Res, (261): 214-23, 1990. 15. Peters, C. L., and Erickson, J. A.: Treatment of femoroacetabular impingement with surgical dislocation and debridement in young adults. J Bone Joint Surg Am, 88(8): 1735-41, 2006. 16. Reynolds, D.; Lucas, J.; and Klaue, K.: Retroversion of the acetabulum. A cause of hip pain. J Bone Joint Surg Br, 81(2): 281-8, 1999. 17. Siebenrock, K. A.; Schoeniger, R.; and Ganz, R.: Anterior femoroacetabular impingement due to acetabular retroversion. Treatment with periacetabular osteotomy. J Bone Joint Surg Am, 85-A(2): 278-86, 2003. 18. Tonnis, D., and Heinecke, A.: Acetabular and femoral anteversion: relationship with osteoarthritis of the hip. J Bone Joint Surg Am, 81(12): 1747-70, 1999. 19. Tonnis, D., and Heinecke, A.: Diminished femoral antetorsion syndrome: a cause of pain and osteoarthritis. J Pediatr Orthop, 11(4): 419-31, 1991. 20. Trousdale, R. T.: Acetabular osteotomy: indications and results. Clin Orthop Relat Res, (429): 182-7, 2004. 21. Wenger, D. E.; Kendell, K. R.; Miner, M. R.; and Trousdale, R. T.: Acetabular labral tears rarely occur in the absence of bony abnormalities. Clin Orthop Relat Res, (426): 145-50, 2004. 22. Wenger, D. R.; Kishan, S.; and Pring, M. E.: Impingement and childhood hip disease. J Pediatr Orthop B, 15(4): 233-43, 2006. 9:06 a.m. Avoiding Prosthetic Impingement Defining the Problem Cecil H. Rorabeck, M.D., F.R.C.S.C. and James Harty, M.D. Prosthetic impingement is a common cause of dislocation and/or excessive wear. It is important to understand the causes and to develop a strategy for avoidance. A number of issues need to be considered in avoiding prosthetic/prosthetic impingement. For example, neck geometry and offset are critical. In addition, one needs to think about taper size. By enlarge, the smaller the taper and the more trapezoidal the neck design, the less likely the patient will have prosthetic impingement. Similarly, acetabular position (lateralized or medialized) can affect impingement as can head size, head extensions (skirts) etc. While there is clearly a movement to alternative bearings which in turn allows for the use of larger femoral heads, very large femoral heads (resurfacing) do not always eliminate the problem with impingement. The foregoing issues will be discussed in the presentation. 9:15 a.m. Combined Anteversion Test, Leg Length and Offset Chitranjan S. Ranawat, M.D. The successful total hip arthroplasty requires achieving initial fixation and stability with appropriate component positioning. When properly performed, the arthroplasty will restore the anatomic geometry of the normal hip. The principles of center of rotation, leg length, and offset must be understood and reproduced to minimize surgical complications. Several tests are available to assess the quality of the arthroplasty including the combined anteversion test, the shuck test, the Ober test, and the range-of-motion test. The combined anteversion test assesses component positioning. With the limb in 10 degrees of adduction, the femoral head should be coplanar with the face of the acetabulum when the limb is internally rotated. The actually amount of combined anteversion can then be measured. For men, the test should read 20-35 degrees of internal rotation. For women, this is increased to 30-45 degrees. The center of rotation is determined by acetabular component positioning. Careful pre-operative templating and the identification of the transverse ligament will prevent errors in component placement such as lateralization. Measuring the distance from the lesser trochanter to the center of the femoral head and reproducing this dimension post-arthroplasty will help to minimize leg length discrepancies. The use of a Steinman pin in the cotyloid groove before and after reconstruction is another method to ensure equalization of leg lengths. Failure to restore component offset may result in instability, limp, and excessive wear. Increasing the offset may lead to pain, stiffness, and functional leg lengthening due to abduction contracture. 9:24 a.m. Using Crosslinked PE with Big Femoral Heads Bas Masri, M.D., F.R.C.S.C. Osteolysis after hip replacement has become the most common reason for long term failure. In the short term; however, dislocation has been one of the most important for reoperation after total hip arthroplasty. Traditionally, smaller femoral heads produced less wear, and therefore, their use became routine in total hip arthroplasty, with 28 mm diameter heads being the standard of care for the majority of patients. In addition, in the early to mid 1990’s, it became obvious that oxidation of the polyethylene, primarily due to sterilization using gamma radiation in air has lead to much higher wear rates and severe osteolysis. Sterilization techniques without gamma radiation were not successful at eliminating osteolysis because they did not allow the cross-linking that gamma radiation allows. In the presence of air, the degree of cross-linking with irradiation is limited by the formation of oxygen free radicals and hydrocarbon chain scission, leading to the higher wear rate. Towards the end of the last century, techniques to maintain cross-linking while eliminating oxygen and free radicals were development. These techniques involved intermediate to high dose gamma irradiation, followed by remelting of the polyethylene to remove any residual free radicals, and sterilization using techniques other than gamma irradiation, such as gas plasma. This allows for the formation of a polymer that is highly cross-linked without oxidation and without the free radicals that might lead to oxidation once the material is implanted. This is now referred to as highly cross-linked polyethylene, and has become the standard of care in total hip arthroplasty. Numerous in vitro and in vivo studies have shown the superiority of highly cross-linked polyethylene in terms of wear and osteolysis. In addition, it has been shown that this material performs well in the presence of debris as well as highly scratched femoral heads. Also, even when the material is scratched, it has been shown that there is no material loss, suggesting that even in such harsh environments, very little wear debris is generated. In addition, unlike standard polytheylene, the wear rate of highly cross-linked polyethylene was not found to be dependent of the diameter of the femoral head, allowing orthopaedic surgeons to use larger femoral heads, and allowing orthopaedic manufacturers to introduce larger femoral heads than ever before. Today, 36mm, 40mm and 44 mm femoral heads are in routine use during primary, and more commonly revision total hip arthroplasty. One of the side effects of high cross-linking is that highly cross-linked polyethylene has inferior tensile strength and fracture toughness when compared to standard, non-oxidized polyethylene. It has to be kept in mind; however, that this comparison is only valid for out of the box non-highly-cross-linked standard polyethylene. Once this polyethylene starts to oxidize, as is does on the shelf and in vivo, its mechanical properties deteriorate. Despite the weaker properties of highly cross-linked polyethylene, biomechanical studies have shown that the stress within the highly cross-linked polyethylene does not change significantly when a larger femoral head is used. In addition, the stresses within highly cross-linked polyethylene when a 36 mm femoral head is used were lower than the stresses in standard polyethylene when a 22 mm femoral head is used. Also, because of its higher wear resistance, highly cross-linked polyethylene is a better material in case of impingement. The use of larger heads is also expected to improve the head neck ratio, overall range of motion and reduce impingement. Consequently, one might expect a reduction in the dislocation rate. It has been shown that the dislocation rate is higher when a smaller diameter head is used for larger cups. Because of its better wear characteristics, highly cross-linked polyethylene is ideal for such cups because of its ability to accommodate head sizes up to 40 – 44 mm , depending on the manufacturer, and leading to potentially much lower dislocation rates. Even in primary hip replacements, larger heads are currently being used with good results, and dislocations are much less prevalent today. Because of its weaker mechanical properties, fractures of highly cross-linked polyethylene have been reported, but primarily when the cup was malpositioned. It is important to remember that a malpositioned socket, particularly with excessive lateral opening, is not an indication for a larger head and highly cross-linked polyethylene because of the risk of polytheylene fracture. If instability is detected intraoperatively, the surgeon has to ensure that the cup is in an adequate position prior to using a larger diameter femoral head with highly cross-linked polyethylene. In summary, the introduction of highly cross-linked polyethylene has allowed us to use much larger femoral head, with significant biomechanical advantages and reduced dislocations. 9:33 a.m. Avoiding Prosthetic Impingement by Using Large MOM Articulations Thomas Parker Vail, M.D. Each new bearing couple brings with it questions that clinical and laboratory experience is beginning to answer. Metal on metal articulations offer the potential for wear rates up to 100 times less than conventional polyethylene, with linear penetration rates on the order of microns. The wear rates represent an order of magnitude improvement over metal on polyethylene, yet the number of very small particles produced by a metal on metal bearing is increased. The lubrication regime of metal bearings (determined by the lambda ratio) favors a high carbon alloy, a highly polished, large diameter with a low clearance (on the order of 100 microns diametrical clearance), and proper positioning of the components to restore normal mechanics and minimize the risk of edge loading. Lubrication theory is supported by wear testing. Other factors such the measurement technique, protein binding, variable baseline levels of metal ions due to environmental exposure, and electrochemical potentials may also play a part in ion release in vivo. The large clinical experience to date has shown hypersensitivity or unusual soft tissue reactions to be a rare and not fully understood clinical problem. The theoretical wear advantage with larger heads combined with the lower risk of dislocation using larger heads has lead to a widespread adoption of metal-metal bearing couples. The range of motion prior to impingement and dislocation is increased as the head size increases, but the added value may diminish beyond a certain point. A monoblock cup clearly offers the option of a larger head size compared to a modular cup when the cup size is 54 mm and below. Failed implant retrievals demonstrate peri-vascular lymphocytic infiltration, but it is not clear that this pathologic finding is isolated to failed metal-on-metal articulations. A causal relationship between implant failure and hypersensitivity has not been established. While a link between metal ions produced by implants and carcinogenesis issue also remains unproven, it cannot be dismissed without continued long term analysis of large numbers of metal on metal devices. The longest clinical data on large metal heads comes from the McKee Farrar implant with reports of 74% survival out to 28 years. More recent reports of metal bearings out to 11 years are limited to the experience with 28 and 32 mm heads. 9:42 a.m. Femoral Design and Impingement Robert B. Bourne, M.D. Range of motion after total hip replacement (THR) is an important contributor to normal hip function. The literature on hip flexion is somewhat confusing, as studies which eliminate pelvic rotation suggest only 90º to 100º flexion, while other reports where pelvic rotation is not controlled report hip flexion in excess of 130º. Johnston and Smidt suggested that 120º of flexion, 20º abduction and 20º abduction and 20º of external rotation were necessary to perform most hip activities in a Western culture. THR studies with both traditional and resurfacing arthroplasties have been demonstrated to potentially restore functional hip range of motion. Component positioning and geometry have been noted to be important factors in minimizing impingement-related polyethylene debris, joint subluxation/dislocation, prosthetic loosening and/or dislodgement of modular liners. Both femoral neck geometry and socket design correlate with hip motion to impingement. The combination of a circulotrapezoidal femoral neck and an acetabular liner with a wide chamfer provides the best results in terms of impingement-free range of motion. Skirted femoral heads should be avoided. Larger femoral heads improve the head:neck range of motion and subsequent hip range of motion, but limited gain is achieved with femoral heads with diameters larger than 36 mm. 10:35 a.m. Why I Do Not Do Resurfacing-Yet William N. Capello, M.D. It has been argued that the current iteration of surface replacement is nothing like that done 30 years ago. I agree that improvements have been made, particularly on the acetabular side and the bearing surface. However, if one is to revisit surface replacements 30 years ago, then it is appropriate to recall at that time the only option available in treating any patient with an arthritic hip was a cemented total hip arthroplasty. The literature at the time also strongly suggested that that approach would not provide a durable result in young active patients. In addition, the only option available for revision of a failed cemented implant 30 years ago was another cemented implant. Again, this proved to be an unsatisfactory solution to that problem. Therefore, an alternative arthroplasty, aimed at the young individual, was a reasonable thought at that time. By saving the femoral canal, one could predict an easier revision and a more predictable revision than was available in revising a conventional total hip. Today, many good options are available for the young active adult, with very low mechanical failure rates out 10-15 years, already published in the literature. In addition, failed loose cementless femoral stems are easier than revising failed loose cemented implants, and the options available to the surgeon today are far superior to those 30 years ago. Therefore, I ask, is the need for yet another option as compelling today as it was 30 years ago? I would suggest it probably is not. The second question I want to raise is what does one gain from using a successful surface replacement? Do they allow for more vigorous activities? There are certainly anecdotal instances where patients with a surface replacement have engaged in extremely vigorous sporting activities, but until long-term follow-ups are available, no one can predict how they will hold up over time. In addition, many currently available conventional hip replacements also tolerate a wide range of physical activities with no obvious deleterious effects. The third question is are surface replacements more durable? As of yet the literature does not support their durability over time. There are yet to be published any series of surface replacements that are comparable to the series and follow-up of young active individuals with cementless arthroplasties. Also, keep in mind that revision is not a benign procedure. It carries many risks, including higher infection rates, potential for nerve and vessel damage, more blood loss, pulmonary embolus, etc. Subjecting our younger patient population to procedures that may not last exposes them to the potential of developing one of these unfortunate complications at revision. I still have reservations about the use of metal-on-metal bearings in the young active population. Although I concede that I know of no evidence that there is a direct link between significant adverse systemic problems and metal-on-metal bearings. In addition, I do not believe that the femoral replacement of today’s surface replacement is significantly different from those done 30 years ago. The concern then, and I believe still now, is that there is significant stress shielding beneath the femoral component that may lead to failure through component loosening or migration. Finally, let me state that surface replacement arthroplasty remains a seductive concept. Its pluses are that it eliminates thigh pain, and it certainly minimizes stress shielding to the proximal femur. I believe that investigators such as Dr. McMinn and Dr. Amstutz are clearly justified in continuing their work in developing and improving this operation. My concern is that the aggressive marketing by some manufacturers of these implants may be somewhat premature, and I believe that we, the orthopeadic community, and our patients would be better served awaiting confirmation of surface replacement’s value in peer reviewed literature before marketing them to the general public. 10:51 a.m. Patient Selection for Total Hip Resurfacing Robert L. Barrack, M.D., Ryan M. Nunley, M.D. and Craig Della Valle, M.D. Metal-metal total hip resurfacing has been the fastest growing arthroplasty procedure worldwide in recent years. Approximately 100,000 procedures have been performed in over twenty countries utilizing second and third generation components in the last ten years. It is generally accepted that only ten to twenty percent of patients with end stage arthritis of the hip are suitable candidates for hip resurfacing versus total hip replacement. The two most crucial factors for achieving success and avoiding complications in hip resurfacing are surgical technique and patient selection. Selection criteria can be classified as either patient factors or anatomic/radiographic characteristics. Important anatomic criteria include normal or near normal bone density, head neck ratio > 1.2, neck length > 2cm, limb length discrepancy < 1cm, neck shaft angle > 120° (some recommend > 130°), absence of cyst or bone defects > 1cm, minimal acetabular dysplasia, and absence of excessive anteversion. Patient factors to avoid are metal sensitivity, renal insufficiency, and women of child-bearing age. Risk factors for early failure or a compromised result that have been described also include female gender especially when associated with small implant size and age >50, diagnosis of AVN especially cystic vs. sclerotic and involving > 25% of the head; BMI > 35 and low pre-operative hip score. Hip resurfacing is also generally selected for patients who have a strong need or desire to resume an activity level beyond what is generally recommended following total hip replacement. Less common indications that have been suggested by experienced resurfacing surgeons include proximal femoral deformity or retained hardware that can make hip replacement extremely complex, patients at high risk for infection or dislocation, and diagnoses associated with poor results with THA such as sickle cell anemia. While outstanding results can be achieved with hip resurfacing it is more demanding both in terms of surgical technique and operative indications. Proper patient selection will be a major factor in the success of hip resurfacing in the United States. 10:59 a.m. Principles of Correct Technique Michael Mont, M.D. Recent studies have shown excellent short- and mid-term results with metal-on-metal total hip resurfacing. Nevertheless, failures rates have ranged from one to fifteen percent in various reports from short-term to mean ten year follow-up with modern generation designs. One of the most dreaded complications and reasons for failure are femoral neck fracture. Reduction of these fractures would be optimal to ensure the high success rate of resurfacing. It has been reported in various multi-center studies that in some centers there is a learning curve involved with reduction of fracture rate. In this study, the individual learning curve will be reported concerning fracture rates in groups of fifty patients through the first five hundred resurfacings that were performed which encompassed a minimum two year follow-up (range, two to eight years). The majority of the early fractures can be attributed to errors in surgical technique that included notching of the femoral neck, performing procedures when there is relative little femoral head and neck bone left or with multiple cysts, or mal-alignments (typically excessive varus) of the prosthesis. These principles of correct technique will be emphasized in terms of how they have influenced the learning curve and reduced the fracture rate. Other principles of correct technique for performing resurfacings will be also emphasized as well. It is hoped that these principles will be generalizable to any surgeons performing hip resurfacing. 11:07 a.m. Is Impingement A Problem After Hip Resurfacing? Harlan C. Amstutz, M.D. and Michel J. Le Duff, M.D. Introduction: Although not a new procedure, hip resurfacing is currently regaining great popularity associated with the use of low-wear metal-on-metal bearings, especially among young and active patients with end stage osteoarthritis. The large femoral head enhances the overall stability but a head-neck ratio inferior to that of modern THR especially with large femoral heads raises concern about a potential risk for impingement. The purpose of our studies was two-fold: 1. To determine the nature and prevalence of impingement after hip resurfacing 2. To assess differences and significance in the measured range of motion (ROM) achieved by a group of bilateral subjects implanted with a resurfacing device on one hip and a THR of varying head size on the other. Materials and Methods: From a series of 1000 Conserve®Plus (follow-up 1.5 to 11 years) we identified 16 hips presenting radiographic evidence of impingement (defined as a smooth concavity on the neck and distinct from neck narrowing). From the same overall series, 29 patients with bilateral implants (one, a Conserve®Plus resurfacing, the other, a conventional THR) were selected for a comparison of range of motion measurements. Femoral head size averaged 46.3mm (38-52) for the resurfaced hips and 35.0mm (28-50) for the hips with a THR. 13 of the hips with a THR had been reconstructed with a large femoral head (36mm or greater - group 1). The other 16 hips with a THR had been reconstructed with a small femoral head (32mm or less - group 2). We performed a comparison of range of motion between resurfaced and THR hips, within group 1 and group 2. Results: 1. Range of motion analysis: In group 1 (n=13, resurfacing head size 44.9mm, THR head size 41.8, p=0.037), no significant difference was observed in flexion arc (119.2 for group 1 vs.118.3 for group 2, p=0.689), abduction adduction arc (71.3 for group 1 vs. 71.7 for group 2, p=0.866) or rotation arc in extension (75.0 for group 1 vs. 80.8 for group 2, p=0.126). Similarly, in group 2 (n=16, resurfacing head size 47.4mm, THR head size 29.5, p=0.0001), we found no significant difference in flexion arc (123.6 for group 1 vs.118.9 for group 2, p=0.115), abduction adduction arc (66.8 for group 1 vs. 63.6 for group 2, p=0.120) or rotation arc in extension (77.1 for group 1 vs. 70.4 for group 2, p=0.066). None of these 29 resurfaced hips showed any radiographic signs of hip impingement or complained of any symptoms that could be associated with ranging their hips in a wide variety of activities. 2. Results of the radiographic analysis and clinical evaluation. 16 hips in 12 patients from the overall series of 1000 hips showed femoral neck remodeling consistent with impingement. The radiographic signs were located posteriorly in 5 hips and superiorly in 12 hips (one hip showed both).These patients all had unusual flexibility with large ROM, significantly different from the rest of the cohort. The average abduction in extension was 55.8 vs. 45.4, p=0.0001 for the hips with a superior impingement sign, and for the hips with a posterior impingement sign the average rotation arc was 100.0 vs. 77.4, p=0.0045. All hips with posterior neck remodeling displayed an apparent excessive anteversion of the acetabular component. The hip with superior remodeling that had the lowest abduction arc (40° in extension, 65° in flexion) had a cup abduction angle of only 33°. A third of these patients were involved in yoga, pilates or ballet dancing. None of these patients had any symptoms or experienced any discomfort when range of motion was tested. We have not identified any similar changes on the anterior aspect of the neck despite the fact it has been our practice not to remove the anterior osteophyte. Discussion: With proper component positioning and a normal ROM, the prosthetic design does not seem to be a limiting factor of ROM as suggested by computer modeling studies1 which do not take into consideration the musculo-tendinous structures surrounding the hip joint and the flexibility diathesis of the patient. Neck remodeling because of impingement appears to be related to socket position i.e. excessive anteversion, producing posterior conflict, and decreased lateral opening causing lateral remodeling in flexible patients. None of our impingers have any clinical symptoms and we have not had any patients with symptoms suggesting ilio-psoas bursitis. However the Conserve®Plus system has a low profile socket and was routinely implanted inferior to the bony rim of the pubis. We conclude from our experience that impingement, despite the lower head-neck ratio of hip resurfacing compared to THR, has not been a significant clinical problem with our Conserve®Plus series. For those patients with evidence of neck-socket impingement, we have not made any recommendation to desist in motion which produces impingement but will continue to follow them closely. Optimal positioning of the acetabular component is the most important factor in preventing impingement and the range of anticipated motion check should be performed before wound closure especially in very flexible individuals. Beaulé et al.2 suggested that the anterior aspect of the head-neck junction could be a site of impingement after resurfacing and that consideration should be given to restoration of a normal head-neck offset at surgery. In our series, the anterior osteophyte was not systematically removed (especially if it contained structural bone) to minimize the risk of neck fracture, but we did not observe any anterior neck impingement. However, we do recommend translation of the femoral component laterally and anteriorly on the neck and on occasion will remove the osteophyte if there is less than ~ 40° of internal rotation in flexion. References: 1. Doherty S, Thompson M, Usrey M, Muirhead-Allwood S, Noble P. Does Hip Resurfacing Restore Normal Range of Motion and Provide Better Joint Motion Than THR? ORS 2008 abstract. 2. Beaulé P, Harvey N, Zaragoza E, Le Duff M, Dorey F. The femoral head/neck offset and hip resurfacing. J Bone Joint Surg Br. 2007;89:9-15. 11:15 a.m. Comparison of Resurfacing and Conventional Results Michael Tanzer, M.D., F.R.C.S.C. When comparing the results of hip arthroplasties, one ultimately must look at the long term survivorship of the implant with respect to loosening and the need for revision. However, modern metal on metal surface replacements (SRA) do not yet have any long-term follow-up and much of the enthusiasm regarding these implants arises from both the actual and potential advantages of their large metal-on-metal femoral heads. The perceived advantages of SRA over conventional total hip arthroplasty (THA) have resulted in their use to treat the young and active patients who historically have not done well with conventional metal on polyethylene hip replacements. However, over decades of innovation, THA in the young patient has evolved from the traditional or conventional Charnley arthroplasty to the use cementless arthroplasties with alternate bearings and larger heads. Comparing metal on metal SRA to conventional arthroplasties would be as unfair as comparing modern alternate bearing THAs to conventional metal on polyethylene SRAs. The purpose of this presentation is to critically evaluate the differences between SRA and THA and compare the results to comparable groups of patients with similar articulating surfaces. 1:35 p.m. The John Charnley Award A Comparison of Three Total Hip Arthroplasty Bearing Surfaces: A Randomized Trial C. Anderson Engh, Jr., M.D., Steven J. MacDonald, M.D., Supatra Sritulanondha, M.P.H., Abigail Thompson, R.N., Douglas Naudie, M.D. and Charles A. Engh, M.D. Metal-on-metal bearing total hip arthroplasty is performed more commonly. There may be differences between manufacturers and head size may affect performance. Validated clinical outcome measures, serum, erythrocyte, and urine ion levels were used in a prospective randomized trial to compare metal-on-polyethylene, 28mm metal-on-metal and 36mm metal-on-metal bearing surfaces. The purpose was to compare a 28mm to a 36mm metal-on-metal bearing and compare the performance of these bearing surfaces to other metal-on-metal bearings using two-year postoperative ion levels. There was no difference in the ion levels for the 28mm and 36mm metal-on-metal bearings. The ion levels in these patients were lower than reported for most other metal-on-metal bearings. Although both erythrocyte and serum cobalt increased, erythrocyte chromium and erythrocyte titanium did not increase despite a 4-6 fold serum chromium and a 3-4 fold serum titanium increase. This may represent a threshold level for serum chromium and serum titanium below which erythrocytes are not affected. 1:44 p.m.The Frank Stinchfield AwardVariation in Postoperative Pelvic Tilt May Confound the Accuracy of Hip Navigation SystemsSebastien Parratte, M.D., Mark W. Pagnano, M.D., Krista Coleman-Wood, P.T., Ph.D., Kenton R. Kaufman, Ph.D. and Daniel J. Berry, M.D. Introduction: Most computer navigation systems used in total hip arthroplasty integrate preoperative pelvic tilt to calculate the anterior pelvic plane. However the consistency of this value after THA has never been proven. Therefore using a modem comprehensive gait analysis before and after arthroplasty we sought: 1. To compare dynamic pelvic tilt changes. 2. To evaluate pelvic flexion/extension range of motion changes. Material and Methods: Twenty-one patients who underwent unilateral total hip arthroplasty were prospectively studied. Quantitative pelvic tilt changes (in the sagittal plane) and pelvic range of flexion/extension motion relative to a laboratory coordinate system were compared using a computerized video motion system. Results: Mean pre-operative gait pelvic tilt was 13.9° ± 4.8° (range, 1.73° to 23.1°), 12.5° ± 4.5° (range, 1.4° to 18.7°) at two month post-operatively 10.5° ± 5.5° (range, -2.36° to 19.2°) post-operatively. A substantial proportion (31%) of patients had more than a 5-degree difference measured between preop and one-year postop and the variability was spread over 20 degrees. Discussion: Substantial dynamic changes in pelvic tilt occurred after THA. While navigation clearly improves component position during THA, the accuracy of component position will be improved because of substantial variation in pelvic tilt from preop to postop. 1:53 p.m. The Otto Aufranc AwardCement Penetration In Hip Resurfacing: Femoral Component Design And Cementation Technique Paul E. Beaulé, M.D., F.R.C.S.C., Wadih Y. Matar, M.Sc., M.D., Philippe Poitras, B.A.Sc., Kevin Smit, B.Sc. and Olivier May, M.Sc, MD Introduction: The amount of cement penetration within the femoral head after hip resurfacing is a recognized factor in femoral failures. However, the factors controlling cement penetration are not yet fully understood. The purpose of this study is to determine the effect of femoral component design on cement penetration. Methods and Materials: Six retrieved femoral heads were resurfaced for each these designs: BHR®, ASR®®, Conserve Plus®, DuROM® and ReCAP® using the manufacturer's recommendations for implantation. In addition, the BHR was implanted using the Conserve Plus®’ high-viscosity cementation technique "BHR/hvt" and vice-versa for the Conserve "Conserve/lvt". Statistical analysis was completed using a one-way ANOVA with Tukey correction (p<0.05). Results: Average cement penetration was significantly highest with BHR 65.62 ± 15.16% compared to: ASR® 12.25 ± 5.12%, Conserve Plus® 19.43 ± 5.28%, DuROM® 17.73 ± 3.96% and ReCAP® 26.09 ± 5.20% (p<0.05). Cement penetration in BHR/hvt remained statistically higher than all other implants equaling 36.7+/-6.6% (p<0.05). A positive correlation was found between the measured design clearance and cement mantle thickness. Conclusion: Femoral component design plays a significant role in cement penetration. Hip resurfacing surgeons need to understand this since excessive or insufficient penetration can lead to early failure. 2:04 p.m. ACCP Guidelines: In Opposition Thomas P. Sculco, M.D. The ACCP guidelines have advocated use of potent anticoagulants in the prophylaxis for thromboembolic disease after total joint arthroplasty. There are significant drawbacks to the use of these agents as advocated by this group. Both increased morbidity and mortality have been reported with these anticoagulants and proven efficacy against fatal pulmonary emboli has not been demonstrated. Significant wound hemorrhage many requiring reoperation has been reported in 3-6% of patients with potent anticoagulation and incidence of increased scar formation (particularly detrimental in TKA patients) and wound and periprosthetic infection is of grave concern. In a recent study from our institution comparing published reports utilizing potent anticoagulants compared to a multimodal approach to prophylaxis encompassing over 27000 patients the incidence of all cause mortality was greater in the potent anticoagulation group and the incidence of clinical nonfatal pulmonary embolus was higher in the potent anticoagulant group. Risk seems to outweigh benefit of following the ACCP guidelines and those developed by the AAOS seem more appropriate for orthopedic patients. 2:12 p.m. Chest Physicians Guidelines: Approve with Reservations Jay R. Lieberman, M.D. The Chest physician guidelines were developed to provide recommendations regarding DVT prophylaxis following total hip and knee arthroplasty. These guidelines are evidenced based and recommendations were made based on the available data. Fortunately, there are numerous randomized trials to help provide information regarding the best modalities to provide prophylaxis after total hip arthroplasty. The Chest physician guidelines recommended the following agents for DVT prophylaxis following total hip arthroplasty: low molecular weight heparin, warfarin, and fondaparinux. Although the guidelines are evidence based they are clearly not perfect. A legitimate criticism has been that there has been a greater focus on efficacy than on safety issues. In addition, when using warfarin the recommendation has been for an INR value between 2 and 3. This recommendation has been made because randomized trials have used these levels. However, there is concern based on the available literature that this leads to too high of a post-operative bleeding rate. The Chest physician guidelines have not recommended aspirin as a prophylaxis agent because there are not enough randomized trials that have assessed the efficacy of this regimen. Aspirin has been shown to be effective in cohort studies but unfortunately it has not been adequately evaluated in a randomized trial. The selection of an appropriate prophylaxis agent is a balance between efficacy and safety. In the future risk stratification based on the procedure and the genetic profile of the patient may enable one to select a specific regimen for each patient. 2:26 p.m. The Position of the AAOS on Thromboembolism Prophylaxis Paul F. Lachiewicz, MD In the guidelines of the American College of Chest Physicians, deep vein thrombosis, after total hip arthroplasty, detected by venography or ultrasonography, is the primary outcome measure.1 These guidelines emphasize prophylaxis with strong pharmacologic agents and seem to under-rate the risks of bleeding and ignore other adverse outcomes (infection, joint stiffness, etc.) related to these agents.2 Symptomatic pulmonary embolism is relatively rare after total hip arthroplasty. In the Scottish Registry, the 90-day rate of fatal pulmonary embolism was 0.22% after 44,785 total hip arthroplasties.3 In the United States, Medicare data have shown that the 90-day rate of nonfatal pulmonary embolism was 0.93% after 58,521 total hip arthroplasties.4,5 Despite the introduction of chemical prophylaxis, there appears to be no change in the rate of symptomatic or fatal pulmonary embolism over the past 10 to 15 years.3,6 The AAOS formed a work group of eight members in early 2006 to develop a new consensus guideline for the prophylaxis of symptomatic pulmonary embolism after total hip and knee arthroplasty. The AAOS work group consulted the evidence review team from the Center for Clinical Evidence Synthesis at Tufts-New England Medical Center. The work group consensus decision was to critically review the literature with the following criteria: prospective studies of total hip and knee arthroplasties performed since 1996 only; cohort studies with ³ 100 patients per group; and randomized control trials with ³ 10 patients per treatment. The evidence review team found no recent study of the natural history without prophylaxis with ³ 1000 patients. The literature review included 2,713 citations from search engines and 10 other recent citations from the work group. Of these 2,714 citations, only 42 articles met the work group criteria. There were 26 articles with cohorts totaling 16,304 total hip arthroplasties. As in the previous AAOS knee osteoarthritis guideline, the individual studies were graded as levels of evidence and the strength of each guideline recommendation was graded on the collection of studies. There were several conclusions of the literature review. The rate of asymptomatic pulmonary embolism was approximately 1 per 300 arthroplasties with treatment. The rate of fatal pulmonary embolism was approximately 1 per 1700 arthroplasties and there was no difference among treatments. The rate of death from bleeding was approximately 1 per 3000 arthroplasties. However, major bleeding complications were more common with systemic pharmacologic prophylaxis (REM summary estimate 1.8%, 95% CI 1.4 – 2.5%) compared to mechanical prophylaxis and aspirin (0.14%, 95% CI 0.03 – 0.8. The AAOS Guideline recommendations from the work group consensus process included the preoperative evaluation of all patients by the orthopaedic surgeon for the risk of pulmonary embolism and the risk of bleeding complications. In consultation with the anesthesiologist, the patient and the surgeon should consider the use of regional anesthesia. The surgeon should consider using mechanical prophylaxis intraoperatively or immediately postoperatively with continuation until discharge. The AAOS Guideline recommendations for medication postoperatively from the literature review and analysis stratify the choices based upon the risks of pulmonary embolism and major bleeding complications. This critical literature review and analysis found no differences among the different thromboembolism prophylaxis interventions in total pulmonary embolism, fatal pulmonary embolism, total death rate, or death from bleeding. Major bleeding was very rare with the intervention of mechanical prophylaxis and aspirin compared to the other interventions. The orthopaedic surgeon should carefully evaluate and document preoperatively each patient’s specific risks for pulmonary embolism and major bleeding. Those patients with a previous symptomatic pulmonary embolism, heritable thrombophilia, hypercoagulable state, or who will not mobilize rapidly are usual examples of patients at elevated risk for pulmonary embolism. With total hip arthroplasty procedures which entail excessive bleeding or patients at higher risk for bleeding in other locations, the orthopaedic surgeon should carefully consider the overall risk-benefit ratio in considering any specific pharmacologic intervention. The AAOS work group encourages future prospective, randomized multicenter studies comparing the various interventions mentioned, as well as new agents, with the clinical endpoints of symptomatic pulmonary embolism and major bleeding which may affect the patient’s outcome. References: 1. Geerts WH, Pineo GF, Heit JA, Bergqvist D, Lassen MR, Colwell CW, Ray JG: Prevention of venous thromboembolism: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy. Chest 2004;126(3 suppl):338S-400S. 2. Callaghan JJ, Dorr LD, Engh GA, Hanssen AD, Healy WL, Lachiewicz PF, Lonner JH, Lotke PA, Ranawat CS, Ritter MA, Salvati EA, Sculco TP, Thornhill TS; American College of Chest Physicians: Prophylaxis for thromboembolic disease: recommendations from the American College of Chest Physicians – are they appropriate for orthopaedic surgery? J Arthroplasty 2005;20(3):273-274. 3. Howie C, Hughes H, Watts AC: Venous thromboembolism associated with hip and knee replacement over a ten-year period: a population-based study. J Bone Joint Surg Br 2005;87(12):1675-80. 4. Katz JN, Losina E, Barrett J, Phillips CB, Mahomed NN, Lew RA, et al: Association between hospital and surgeon procedure volume and outcomes of total hip replacement in the United States medicare population. J Bone Joint Surg Am 2001;83-A(11):1622-9. 5. SooHoo NF, Lieberman JR, Ko CY, Zingmond DS: Factors predicting complication rates following total knee replacement. J Bone Joint Surg Am 2006;88(3):480-5. 6. Lie SA, Engesaeter LB, Havelin LI, Furnes O, Vollset SE: Early postoperative mortality after 67,548 total hip replacements: causes of death and thromboprophylaxis in 68 hospitals in Norway from 1987 to 1999. Acta Orthop Scand 2002;73(4):392-9. 2:34 p.m. Venous Thromboembolism Prophylaxis: Clinical Outcomes with Chemoprophylaxis Vincent D. Pellegrini, M.D. Fractionated heparins and pentasaccharide are the most effective agents in reducing venographic DVT after total hip arthroplasty. However, low-intensity warfarin (target INR 2.0) combines safety, by avoidance of bleeding complications, with efficacy in secondary prevention of clinical VTED events after total hip arthroplasty. As such, warfarin represents a “therapeutic compromise”; less dramatic primary prevention of venographic thrombosis is accepted in exchange for a lower bleeding rate than is seen with newer agents that more completely eliminate venographic thrombosis. In 1,972 patients, 1,032 completed screening contrast venography; 175 (16.9%) had deep venous thrombosis. Patients discharged on warfarin had a 0.27% (1/360) readmission rate compared with 2.2% (19/880; p=0.02) for patients with negative venograms discharged without further anticoagulation. Three patients (0.15%) suffered a fatal pulmonary embolism; each had negative venography and no outpatient prophylaxis. Major bleeding (0.05%) resulted in one death from an intracranial event. Surveillance venography was a poor predictor of thromboembolism risk and need for extended anticoagulation therapy. Routine secondary prophylaxis with extended low-intensity (INR 2.0) warfarin reduces venous thromboembolism-related readmission with negligible bleeding risk. 2:42 p.m. Multimodal Prophylaxis and Aspirin Eduardo A. Salvati, M.D., Nigel E. Sharrock, Alejandro Gonzalez Della Valle and Thomas P. Sculco, M.D. During the last four decades we have developed a multifaceted approach to prevent VTE following THR.1 Preoperative measures include discontinuation of procoagulant drugs, timed according to their known half-life, and autologous blood donation. Regional anesthesia minimizes the risk of thromboembolism by enhancing blood flow and hypotension reduces blood loss and provides a bloodless field, which expedites surgery. The intraoperative hypercoagulable state, which is strongly activated during femoral instrumentation, is minimized by a small dose of intravenous intraoperative heparin (10U/kg) administered prior to femoral work and by repeated lavage and aspiration of the intramedullary contents. The duration of the femoral vein occlusion, caused by the extreme position of the lower extremity during femoral work, is kept to a minimum to reduce venous stasis and endothelial injury. Preheating the femoral component to ± 43º C shortens cement polymerization by ± 5 minutes. Immediately after surgery, venous flow is enhanced with intermittent pneumatic compression. As soon as the muscle function is recovered the patient is strongly urged to perform repeated and vigorous active flexion-extension exercises of the ankles and start early ambulation. Aspirin (325mg bid) is administered to patients with no predisposing factors for VTE and who mobilize promptly (83%). Aspirin prophylaxis is safe, inexpensive, well tolerated, easy to administer, requires no monitoring and has analgesic and antipyretic effects. Aspirin also reduces the risk of arterial complications and of ectopic ossification. Warfarin is administered to patients who were already receiving it before surgery or who have a recognized predisposition for VTE (17%).2 This multimodal approach is beneficial on all three components of Virchow’s Triad (venous stasis, endothelial injury and hypercoagulability) rather than relying only on postoperative anticoagulation. It has resulted in very low rates of symptomatic VTE in 2032 THA prospectively studied (2.5% DVT and 0.6% PE, none fatal), with no bleeding complications. 3 We recently conducted a meta-analysis of the English literature published from 1996 to 2006 to determine whether potent anticoagulants (LMWH, ximelagatran, fondaparinux, or BAY 59-7939) confer any benefit on mortality during the first 3 months after THA and TKA. The meta-analysis showed potent anticoagulation in 14,750 TJR did not prevent PE and was associated with the highest all-cause mortality (0.47%). The multimodal approach (regional anesthesia, pneumatic compression, and aspirin) in 7193 TJR demonstrated the lowest all-cause mortality (0.19%; p = 0.003); warfarin in 5006 TJR was associated with an intermediate all-cause mortality (0.41%).4 Other authors have also reported on the increase risk of bleeding with aggressive anticoagulation.5,6 In conclusion, our multimodal prophylaxis is safe and effective. Following this protocol, the postoperative anticoagulation does not need to be aggressive in the patient with no predisposing factors for VTE and who mobilizes promptly. 1. Salvati EA, Sharrock NE, MB, Westrich G, Potter HG, Gonzalez Della Valle A, Sculco TP. Three decades of clinical, basic, and applied research on thromboembolic disease after THA. The 2007 ABJS Nicolas Andry Award. Clin Orthop Relat Res. 2007;459:246-254. 2. Beksac B, Gonzalez Della Valle A, Salvati EA. Thromboembolic disease after THA: Who is at Risk? Clin Orthop Relat Res. 2006;453:211-224. 3. Gonzalez Della Valle A, Serota A, Sorriaux G. Go G, Sharrock NE, Sculco TP, Salvati EA. Venous thromboembolism is rare with a multimodal prophylaxis protocol after THA. Clin Orthop Relat Res. 2006;443:146-153. 4. Sharrock NE, Gonzalez Della Valle A, Go G, Salvati EA. Potent anticoagulants are associated with a higher all-cause mortality after THA and TKR. Clin Orthop Relat Res. 2008;466:714-721 5. Callaghan J, Dorr LD, Engh GA, Hanssen AD, Healy WL, Lachiewicz PF, Lonner JH, Lotke PA, Ranawat CS, Ritter MA, Salvati EA, Sculco TP, Thornhill TS. Prophylaxis for thromboembolic disease. J Arthroplasty. 2005;20:273-274. 6. Burnett RS, Clohisy JC, Wright RW, McDonald DJ, Shively RA, Givens SA, Barrack RL. Failure of the American College of Chest Physicians-1A protocol for lovenox in clinical outcomes for thromboembolic prophylaxis. J Arthroplasty. 2007;22:317-324. 3:21 p.m. The Transverse Acetabular Ligament as a Guide to Anteversion In Total Hip Arthroplasty Mark W. Pagnano, M.D. Malposition of the acetabular component in total hip arthroplasty has been associated with instability, wear, impingement and the need for revision surgery. Substantial attention has been devoted to strategies to reliably and reproducibly choose the orientation of the acetabular component at the time of THA. In the current era in which many THA are done with smaller incisions there are fewer bony landmarks readily identifiable by the surgeon intraoperatively and that may make acetabular component orientation even more challenging. Some surgeons spend considerable time and effort preoperatively to position the patient on the operative table; but that strategy has limitations as our patient population includes greater numbers of obese and morbidly obese patients. Computer navigation has been introduced as a mechanism to improve the reproducibility of acetabular component position; but the early results with navigation have shown little or no measurable clinical benefit. Substantial scientific discussion continues to be carried out to define the ideal acetabular component position to aim for with the computer in individual patients. Other discussions revolve around the ideal strategy to deal with pelvic tilt and the confounding fact that some patient’s pelvic tilt changes substantially from preoperative to post-THA while other patient’s pelvic tilt does not change. Archbold et al. have recently reported the results of 1000 consecutive THA using the transverse acetabular ligament as a guide to acetabular component position. In those 1000 consecutive cases done through a posterior approach the TAL was used to establish acetabular anteversion and the depth of acetabular reaming; a formal posterior capusular repair was also done and those authors found a 0.6% incidence of dislocation. The transverse acetabular ligament (TAL) is a structure that can be identified reliably in almost all hips at the time of THA. In some cases the TAL is covered by soft tissue or bone that requires removal in order to see it effectively. The TAL extends across the inferior edge of the acetabulum over the inferior acetabular notch and acts as the inferior extension of the acetabular labrum. The TAL forms a straight line that can be used to define the anteversion of the acetabulum; the acetabular component can be positioned parallel to the TAL to define the anteversion. In addition the TAL can be used as an aid in determining the depth of acetabular reaming as the inferior edge of the acetabular component should lie just deep to the most superficial fibers of the TAL. Archbold HAP et al: The transverse acetabular ligament an aid to the orientation of the acetabular component during primary THA. JBJS Br 2006;88:883-886. 3:29 p.m. Anatomic Landmarks for Acetabular Positioning: The Sciatic Notch & Acetabular Anteversion James A. D’Antonio, M.D. Acetabular preparation and component positioning has a direct effect on hip biomechanics, bearing surface wear, functional ROM and stability, leg length, and presents the greatest challenge for a successful THA. Anatomic cadaver studies have shown that the true anteversion varies between 19°-21° and abduction 50°-55°. Cup positioning during THA is a 3D combination of abduction and version with version being a combination of IR and flexion. Computer ROM models demonstrate the following to maximize functional ROM: an abduction angle between 45°-55°; anteversion angle between 20°-30° given femoral anteversion of 10°-15°; combined femoral acetabular anteversion of 35°-40°. Acetabular components can be positioned utilizing external alignment guides, navigation, or anatomic landmarks. External alignment guides are notoriously inaccurate because there is no accounting for pelvic tilt and/or flexion when the patient is in the lateral decubitis position. The desired acetabular position can be achieved utilizing the following anatomic landmarks: the ishium (flush with the posterior wall); inferior rim; anterior rim; and the sciatic notch, a reliable indicator for acetabular anteversion. The notch acetabular angle (89°) is defined as a line from the AP rims that intersects a line from the posterior rim to the top of the sciatic notch. Paralleling that posterior rim to sciatic notch line on insertion will essentially yield an anatomic anteversion of 20°. For the majority of patients, a more desirable increased anteversion of 25°-30° requires that the insert direction be angled posterior to the top of the sciatic notch. This position of increased anteversion will typically result in the cup being placed inside the anterior wall, and flush with the posterior wall. Positioning the bottom of the cup within the inferior rim will keep the cup at the desired 45°-55° abduction angle. Utilizing these techniques, 631 consecutive primary total hips performed through a posterior approach over a five-year period have a dislocation rate of 0.34% (2 cases). Measured mean abduction was 49.1° with a +/- 5° variation in 82% of cases and a +/- 10° variation in 98% of cases. The acetabular anteversion was consistently within +/- 5° of the mean in 97% of cases and within +/- 10° in 100% of cases studied. Acetabular component positioning has a significant effect on the long-term success of THA. Utilizing anatomic landmarks including the sciatic notch as a guide for anteversion, accurate and consistent positioning of the socket can be achieved in a high percentage of cases. 3:37 p.m. Acetabular Orientation: Anterolateral Approach in the Supine Position Richard H. Rothman, M.D., Ph.D. and Matthew S. Austin, M.D. Total hip arthroplasty is one of the most successful operations performed today. The acetabular component is the keystone to the success of the procedure. The goal of proper acetabular component placement is to minimize dislocations and avoid impingement. This goal is affected by the surgical approach, orientation of the pelvis, and choice of bearing surface. The authors present their approach to acetabular component orientation via the anterolateral approach in the supine position. 3:45 p.m. Combined Anteversion Technique for Cup Position Lawrence D. Dorr, M.D. Conversion from cemented stem fixation to cementless stem use changes the requirements for cup position. Cemented stem position can be reliably fixed between 10-20 degrees anteversion, so targeting cup anteversion at 20 degrees will most often result in a combined anteversion of 30-45 degrees. Cementless stem position is between 10-20 degrees anteversion in only 43% of hips; 10% are in absolute retroversion; 42% between 0-9 degrees anteversion; and 5% more than 20 degrees anteversion. The mean anteversion for cementless stems is between 8-10 degrees, lower in men. Men are lower because young men have more retroverted femurs. The loss of control of stem anteversion is because of a rigid metal stem in a fixed bone shape. Cup position must be customized to the patient for two reasons: Cementless stem position and pelvic tilt. Pelvic tilt results in a cup position 10 degrees different than expected in 7.5% of hips and 6-9 degrees different in 21% of hips. The rationale for the combined anteversion technique of THR is the necessity to customize the cup anteversion for the achieved cementless stem anteversion. The safe zone for this combined anteversion is 25-50 degrees. The most accurate method for making the decision for cup position is with imageless computer navigation which permits cup anteversion adjusted for pelvic tilt (functional cup position) and for the inflexible cementless stem anteversion. 3:53 p.m. Cemented Liners Into Shells John J. Callaghan, M.D. There are several clinical scenarios to consider cementing an acetabular liner into a secure cementless shell including cases of: 1) inadequate capturing mechanism, 2) damaged locking mechanisms, 3) unavailability of the mating polyethylene liner, 4) instability following debridement for wear, 5) instability at the time of femoral side revision, and 6) recurrent dislocation. The last two situations are common scenarios for cementing a constrained liner into a secure shell. Technique includes: 1) scoring the shell in cases with no screw holes or polished inner shells, 2) scoring the acetabular liner in a “spider web” pattern, 3) pressurizing cement into the shell, and 4) inserting a liner that allows 2 millimeters of cement mantle. Results of Cementing Constrained Liner Into Secure Cementless Shell A. Callaghan et al. JBJS 2004 i. 31 hips ii. 2-10 year follow-up iii. 2 of 31 failed iv. Technical considerations 1. Do not cement proud 2. Do not cement into a malpositioned shell B. Haft et al. J Arthroplasty 2002 i. 17 hips ii. Minimum 1 year follow-up iii. 1 of 17 failed iv. Technical considerations 1. Do not cement proud Results of Cementing Non-Constrained Liners Into Secure Cementless Shell A. Beaule et al. JBJS 2004 i. 32 hips ii. Mean 5.1 year avg f/u iii. 4 components revised for loosening References: 1. Beaule PE, Ebramzadeh E, LeDuff M, Prasad R, Amstutz HC. Cementing a liner into a stable cementless acetabular shell: the double-socket technique. JBJS 86-A, 2004, pp 929-34. 2. Callaghan JJ, Parvizi J, Novak CC, Bremner B, Shrader W, Lewallen DG, Johnston RC, and Goetz DD. A constrained liner cemented into a secure cementless acetabular shell. JBJS 86-A, 2004, pp 2206-11. 3. Goetz DD, Bremner BR, Callaghan JJ, Capello WN, and Johnston RC. Salvage of a recurrently dislocating total hip prosthesis with use of a constrained acetabular component. A concise follow-up of a previous report. JBJS 86-A, 2004, pp 2419-23. 4. Haft GF, Heiner AD, Dorr LD, Brown TD, and Callaghan JJ. A biomechanical analysis of polyethylene liner cementation into a fixed metal acetabular shell. JBJS 85-A, 2003, pp 1100-10. 5. Haft GF, Heiner AD, Callaghan JJ, Dorr LD, Wan Z, Long W, Longjohn DB, and Brown TD. Polyethylene liner cementation into fixed acetabular shells. J Arthroplasty 17(4 Suppl 1), 2002, pp 167-70. 4:20 p.m. Revision of Surface Replacement Michael Mont, M.D. This presentation will describe video techniques for revising a failed surface replacement. Most of the revisions will be for femoral neck fractures. In this situation, one can revise to a standard total hip replacement and also revise the acetabulum. Fortunately, most prosthetic companies have availability of modular heads that can fit into the acetabular component and fit in to enable leaving the acetabular component. In multiple studies, the revision of a surface replacement has not been found to be more difficult than primary total hip arthroplasties. 4:27 p.m. Monoblock Femoral Revision Thomas K. Fehring, M.D. The ideal femoral stem is easy to insert, has reproducible results, and is able to handle most revision situations. While no stem is appropriate for all revisions, extensively coated stems are appropriate to manage Type I through III defects where isthmic bone is available for fixation. The use of this stem is not appropriate in a Type IV defect where the metaphysis is nonsupportive and the diaphysis is not intact due to severe bone loss. In this situation, reliable distal fixation with an extensively coated stem is not possible and other alternatives should be sought. For most revisions however, the workhorse for femoral revision has been monoblock extensively coated stems. To optimize results careful preoperative planning should be done to ensure 4-6 cm. of intimate endosteal contact or “scratch fit”. It is important to template the lateral as well as the AP film to assess femoral bow. Proper surgical technique is also important to achieve stable fixation in a revision situation. After implant removal, reaming proceeds until a tight fit over a 4-6 cm. diaphyseal segment is obtained. Intraoperative x-rays are useful to confirm appropriate alignment, appropriate size, and complete cement removal. When using a straight stem one under-reams by .5 mm. When using a curved stem reaming is dependent on bone quality and length of the curved stem. In preparation for implanting a straight stem, one should insert a reamer the same diameter as the final implant to determine the amount of scratch fit that will occur. The reamer should “catch” or “hang up” at least 4-6 cm. above the predetermined seating level. Stem impaction should be slow and methodical. The implant should advance with each blow. The surgeon should pause periodically to let the bone accommodate to the implant. Full impaction can take up to five minutes. Excellent results have been reported using this type of implant with this surgical technique (1,2,3). Non-modular extensively coated stems must be considered the gold standard for femoral revision of Type I through III femoral defects. References: 1. Paprosky WG, Greidanus NV, Antoniou J: Minimum 10-year-results of extensively porous-coated stems in revision hip arthroplasty. Clin Orthop 369, 1999. 2. Moreland JR, Moreno MA: Cementless femoral revision arthroplasty of the hip: Minimum 5 years follow-up. Clin Orthop 393, 2001. 3. Nadaud MC, Griffin WL, Fehring TK, Mason JB, Tabor Jr T, Odum S, Nussman DS: Cementless revision total hip arthroplasty without allograft in severe proximal femoral defects. J Arthroplasty 20 (6), 2005. 4:35 p.m. Modular Femoral Revision Wayne G. Paprosky, M.D., F.A.C.S. Introduction: Significant femoral bone loss can be encountered in the multiply revised patient. Deficient proximal bone requires either a bulk allograft or a femoral component that allows stable distal fixation. Modular tapered stems have been utilized by the senior author in patients with severe femoral deficiency (Type III B and Type IV bone) as the relatively poor results of fully porous coated stems were evaluated. This study will review our current experience with the use of a modular tapered stem in patients with Type IIIB and Type IV femoral defects. Materials and Methods: 24 patients had a femoral revision for a Type III B or Type IV femoral defect between 2000 and 2005 using either a Link (Link Orthopaedics, Pine Brook, NJ) or ZMR (Zimmer, Warsaw, Indiana) modular tapered prosthesis. 13 patients were identified to have a Type III B defect and 11 patients had a Type IV defect. Surgical indication was aseptic loosening for 14 patients, second stage re-implantation for infection in four patients and a peri-prosthetic fracture in six patients. A posterior approach was used in all patients. An extended trochanteric osteotomy was performed in 16 of the 24 patients. The acetabular component was revised in 15 of the 24 revisions. Fifteen patients had a XL taper ZMR, two patients had a Link prosthesis and seven patients had a non XL tapered ZMR. The average follow-up for the entire cohort of revision patients was 3.0 years (range, 2-5 years). Post-op, all patients’ hips were placed in an abduction brace with toe-touch weight bearing for 6 weeks post-op before being advanced to weight bearing as tolerated. Results: Of the twenty-four patients included in this study, one patient required femoral re-revision for sepsis and this same individual required a constrained liner for recurrent dislocation. One patient had a femoral re-revision for subsidence and was revised to a larger diameter ZMR. One patient had a fracture of the ZMR taper and this was revised to an XL taper. Functional outcomes demonstrated that three patients required the use of a walker, five patients required the use of a came and sixteen patients walked without assistive devices. Twenty-four patients had no pain or minimal pain and four patients reported moderate pain. One patient later required femoral re-revision for septic loosening. There were no components revised for aseptic loosening and none of the unrevised components showed subsidence. Discussion: Extensively coated stems have shown excellent results for many revisions, but have shown higher rates of failure among patients with femoral remodeling in retroversion, an enlarged endosteal diameter or an ectatic canal. A modular tapered implant provides axial and rotational stability through the use of distal splines while the proximal body segments can allow independent adjustment of leg length, offset and anteversion. Based on our results, the use of a modular stem is an alternative option when dealing with a severely bone deficient femur. 4:42 p.m. Revisions of the Patulous Intramedullary Canal David G. Lewallen M.D. Routine femoral revision surgery is dependent on the achievement of stable support and maximal contact on host bone. The majority of femoral revisions are currently non-cemented and employs monoblock or modular implants generally inserted so as to engage intact host bone distal to the prior failed implant, bypassing the damaged proximal femur. Multiple failures of progressively longer and larger diameter implants, and/or infection of a prior arthroplasty, can lead to a markedly enlarged, patulous femoral canal with cavitary or segmental deficiency that extends beyond the diaphysis and into the distal femur. Stable support of even the largest diameter extensively coated cylindrical or modular tapered implants may not be possible when bone damage extends down to the distal metaphyseal level. Options for femoral reconstruction in instances where cavitary or segmental deficiency and canal enlargement precludes use of standard revision devices include: 1. Cemented stem fixation into the expanding distal metaphysis 2. Long stem impaction grafting with adjunctive strut grafting to prevent stem tip fracture 3. Intramedullary (Intussusception) Femoral Allografting with cemented femoral stem fixation into the allograft. 4. Custom Highly Porous Metal Intramedullary Femoral Augments as a “prosthetic allograft” used in the manner of an Intussusception Bone Graft. 5. A Total Femoral Replacement Prosthesis Each of these methods has specific advantages and disadvantages at present. The availability of off the shelf, cost effective, modular intramedullary femoral augments would greatly facilitate and simplify the reconstruction of these most challenging of femoral revision procedures. 4:50 p.m. Revision of Absent Proximal Femur Allan E. Gross, M.D., FRCSC Uncontained femoral defects greater than 8cms in length can be managed by tumour prostheses, distal fixation implants, or proximal femoral allografts. Tumour prostheses and distal fixation implants require at least 6cms of diaphyseal bone for fixation, do not provide a good environment for reattachment of bone and muscle, and are difficult to re-revise. Proximal femoral allograft reconstruction allows for attachment of bone and muscle, does not require distal fixation, and can be used if less than 6cms of diaphyseal bone is available. Our technique does not violate the host canal with cement or an ingrowth surface thereby facilitating future revision surgery. The long stem implant is cemented into the allograft only and the allograft host junction is stabilized by a step cut or oblique osteotomy and cortical struts if necessary. 93 PFA’s were student in 92 patients with a follow-up of 15 years or greater. The average age was 63 years (range 49-81 years). The average number of previous revision procedures was 2.5 (range 1-5). Radiographic assessment of the construct looking for allograft-host union, component stability, trochanteric union, graft fracture and resorption was performed and survivorship of the construct was analyzed. At 15 year review 36 patients had died (34 with the original PFA in situ) and 6 were lost to follow-up. The average length of the PFA was 14.7 (range 8-32cm). Failure due to infection occurred in 4.4% and of these 50% were successfully revised. Aseptic loosening occurred in 5.9%. Non-union occurred in 5.5% and dislocation in 9%. Revision of the PFA for all reasons excluding the acetabulum was performed in 10.7% of cases. A successful construct, defined as a stable implant with no need for re-revision surgery at the time of latest follow-up, was seen in 83.1%. Proximal femoral allograft for revision hip arthroplasty in femoral segmental bone loss proves to be an excellent and durable alternative at an average follow-up of 15 years. 4:57 p.m. Two-Stage Management of Infection After Hip Replacement Using an Interval Antibiotic Spacer Clive P. Duncan, M.D., M.Sc., FRCSC The concept of the PROSTALAC, an acronym meaning prosthesis of antibiotic loaded acrylic cement was developed in 1986. The rationale was to deliver a high end prolonged dose of antibiotic locally to the infected tissues, while maintaining anatomy, mobilizing the patient and facilitating the second stage. Basic science and clinical outcome studies over the past 20 years have purported the safety and efficacy of this technique. A most recent study of 99 patients, with a follow up of 10-15 years, at our centre has demonstrated a 96% success rate long term and patient-reported outcomes that are indistinguishable from those achieved with revision of the non infected case. The principles underlying the technique include identification of the organism(s) and the antibiotic sensitivity profile before operation, adequate debridement and removal of all foreign material, the stable but non-rigid implantation of a facsimile of a hip using antibiotic-loaded acrylic, no drains (so as to avoid removal of antibiotic-rich periprosthetic fluid), secure wound closure and rapid patient mobilization. ????? follows six weeks of intravenous antibiotics, reinvestigation of the patient to rule out persistence of infection, and reintervention to reconstruct the hip at an average of 12 weeks after the first stage. A variety of PROSTALAC systems are available to the surgeon, basic ‘homemade’ models constructed in the OR, or a variety of propriety systems available on the market. The system we use includes a metal stem, a snap-fit socket, PLAKOS cement, antibiotics based on the organism and sensitivity profile as well as a system of molds manufacture the system during the case. President: Lawrence Dorr, M.D. First Vice-President: Wayne Paprosky, M.D. Second Vice-President: William Maloney, M.D. Secretary-Treasurer: Vincent Pellegrini, M. D. Member At Large: Steven MacDonald, M.D. Chairman Ed Committee: Douglas Dennis, M. D. Immediate Past President: John Callaghan, M. D. President: Daniel J. Berry, M.D. 1st Vice President: David G. Lewallen, M.D. 2nd Vice President: William J Robb, III, M.D. 3rd Vice President: Mary I. O’Connor, M.D. Treasurer: Carlos J. Lavernia, M.D. Secretary: James B. Stiehl, M.D. Immediate Past Presidents: William J. Hozack, M.D. Joseph C. McCarthy, M.D. Educational Committee Chair: Thomas P. Schmalzried, M.D. Members At Large: Michael H. Huo, M.D. Audley M. Mackel, III, M.D. Arlen D. Hanssen, M.D. Steven M. Teeny, M.D. |
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