We studied 75 primary total knee arthroplasties (TKAs) performed using a single-radius, high-flex posterior-stabilized insert design with a minimum 5-year follow-up to document its implant specific complications and clinical results. Nonprogressive osteolysis was observed at zone 4 of the femoral component in 6 knees (8%) and at zone 1 of the tibial component in 6 knees (8%). However, no complications associated with high flexion designs, such as early aseptic loosening, were observed.Preoperatively, mean Knee Society Knee Score and Knee Society Function Score were 55.1 and 45.5, respectively (range, 10-83 and 20-80, respectively). At last follow-up, mean Knee Society Knee Score and Knee Society Function Score improved to 94.9 and 85.9, respectively (range, 70-100 [P<.0001] and 45-100 [P<.0001], respectively). Mean maximal flexion was 122.1 degrees (range, 90 degrees -140 degrees ) and mean range of motion (ROM) was 110.3 degrees (range, 80 degrees -135 degrees ) preoperatively, and these values improved to 128.9 degrees (range, 110 degrees -150 degrees [P<.0001]) and 127.8 degrees (range, 110 degrees -150 degrees [P<.0001]), respectively, at last follow-up. Preoperative ROM was found to be the only factor significantly correlated with postoperative ROM at last follow-up by univariate (P=.0020) and multivariate analysis (P<.0067). Accordingly, clinical results were comparable to previous reports of high-flex implants without implant-specific complications.
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