Minimum 15-Year Survival Of A Biconvex Inlay Patellar Component In Primary Total Knee Arthroplasty: An Analysis Of 2,530 TKA From A Single Institution.

INTRODUCTION: Routine patellar resurfacing during primary total knee arthroplasty (TKA) remains controversial. To our knowledge, there are no studies reporting the long-term performance of a cemented biconvex all-polyethylene inlay component implanted at the time of primary TKA. The purpose of this study was to examine the 15-year survivorship and long-term clinical outcomes of this biconvex inlay patella used at our institution.

METHODS: We retrospectively reviewed our prospectively collected institutional database and identified 2,530 patients who underwent cemented TKA with a single prosthetic design (from 1996 to 2007) where the patella was resurfaced using this cemented biconvex inlay patellar. The mean age at surgery was 68 years (range, 29 to 93). The mean body mass index was 33.0 (range, 16.4 to 76.3), with 61.9% women. At the time of analysis, the mean time from surgery was 20.4 years (range, 15 to 26). We used Kaplan-Meier analysis to calculate survivorship at 15 years. We analyzed clinical outcomes using three patient-reported outcome measures collected prospectively.

RESULTS: The 15-year survivorship with revision surgery for all causes as the end point was 97.1 % (95% CI [confidence interval] 96.1 to 98.1%). The 15 year survivorship with revision surgery for a patella-related complication as the end point was 99.7% (95% CI 99.4 to 1.0). At a minimum of 13 years post-TKA, patients showed significant improvement in scores for the Knee Society Clinical Rating System (P < 0.001), Western Ontario and McMaster University Osteoarthritis Index (P < 0.001), and Veterans Rand 12 Item Health Survey physical component (P < 0.001).

CONCLUSION: Routine patellar resurfacing using a biconvex inlay patellar component has excellent survivorship and a low rate of complications at 15 years post-TKA.