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compared to the attending surgeon.DiscussionProper implant orientation is critical to the long term success of a total hip arthroplasty,especially with newer hard bearings. Evaluation of this orientation is also an important part ofpre-operative planning in revision surgery. While leg length discrepancy and offset mismatchare easy to determine based on post-operative x-rays, assessing stem rotation usuallyrequires more powerful imaging methods which are costly and may havesome morbidity. While surgical positioning of stem rotation of many popular proximally fixedtapered cementless stem designs can not be adjusted without significant intra-oparative fracturerisk, the distally fixed rectangular Zweymuller-type stems can accomodate near infinite stemanteversion safely. Our modification to this design enhances its functionality since it can aid infuture pre-operative revision planning should the bearing or acetabular component fail.Poster: 11Isolated Patellar Arthroplasty at 15-Years: Dramatic Femoral, Tibial andPatellar Osteolysis : Not a "Simple Revision".*R Stephen J Burnett - Vancouver Island Health South Island - Victoria, CanadaRajesh Nair - All-Saints University - victoria, CanadaJames D Warren - Vancouver Island Health-South Island - Victoria, Canada*Email: rsjburnett@gmail.comIntroduction: Isolated patellar arthroplasty (IPA) was performed prior to the advent ofpatellofemoral arthroplasty (PFA) for selected indications. The patella was resurfaced and thetrochlea left unresurfaced. No studies of the long-term outcomes of IPA have been reported.The purpose of this study is to present a case with minimum 15-year follow up of IPA.Methods: A 45 year-old female underwent IPA in 1994 for isolated patellar cartilage loss andosteoarthritis, and failed prior treatments(arthroscopy x3, open lateral release) with an allpolyethylene 2-peg cemented patellar component (GUR 1050 ram extruded, g-air sterilization).At 15-years postop, she presented with anterior knee pain, swelling, effusions. Imagingdemonstrated dramatic osteolysis involving the patella, posterior tibial PCL origin, and thefemoral epicondylar collateral ligament origins. The remaining patellar host bone shell was verythin, with moderate OA of the tibia-femoral joint.Results: Conversion to cemented total knee arthroplasty (TKA) was performed withbonegrafting of osteolytic defects, PCL substitution and a stemmed tibial component, andrevision of the patella to a porous metal cementless implant. At 2-years follow up she is painfree, with radiographs demonstrating anatomic implant alignment and the porous metal patellarcomponent ingrown.Discussion: This report demonstrates the dramatic longterm effects of polyethylene wear thatmay occur with patellar arthroplasty. Osteolysis involving not only the patella, but the tibia andfile:///E|/ISTA2010-Abstracts.htm[12/7/2011 3:15:47 PM]