Effect of Radiation, Heat, and Aging on In Vitro Wear Resistance of Polyethylene

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Abstract
Using a unique community implant and explant registry, long-term survival of unicompartmental knee arthroplasty was examined and compared with total knee arthroplasty (TKA) survival. All patients with unicompartmental knee arthroplasties done since September 1, 1991 were followed up prospectively to January 31, 2002 to assess survival and reason for revision. Five hundred sixteen unicompartmental knee arthroplasties of nine different designs were done by 23 surgeons. During this period, 39 of the 516 unicompartmental knee arthroplasties were revised. The major revision reasons for unicompartmental knee arthroplasties were progression of arthritis in the uninvolved compartments (51.3%), aseptic loosening (25.6%), and PE wear (20.5%). Kaplan-Meier survival analysis with revision as the end point revealed survival of 92.6% (range, 90.0%–95.2%) at 5 years for these unicompartmental knee arthroplasties and 88.6% (range, 85.0%–92.2%) at 10 years, compared with 94.8% (range, 93.5%–96.0%) at 10 years for primary TKAs. This community registry experience may more accurately reflect the results obtained in community practice, with different surgeons, varying indications, and numerous designs. The current study showed that revision of unicompartmental knee arthroplasties is done most commonly for progression of arthritis in the contralateral compartment, and at a higher rate than revision of primary cemented TKA.