Total Hip Arthroplasty with Use of the Cementless Zweymuller Alloclassic System A Concise Follow-up, at a Minimum of 25 Years, of a Previous Report

We previously reported the 10 to 13-year follow-up results for 104 total hip replacements with the Zweymuller Alloclassic stem and a threaded cup in 94 patients. The present study is a clinical and radiographic outcome update after a minimum follow-up of 25 years. Four patients (4 hips) were lost and 46 patients (50 hips) died, leaving 44 patients (50 hips) available for follow-up. Since our previous report, 7 cups and 2 stems were revised. At 20 years, the probability of survival of any component was 84.1% (95% confidence interval [CI], 73.91% to 94.29%) and the cumulative probability of not having stem loosening was 95.9% (95% CI, 95.51% to 96.29%). We observed proximal femoral osteolysis in 15 hips (30%), cortical hypertrophy in 21 hips (42%), and proximal femoral osteopenia in 30 hips (60%). The Zweymuller Alloclassic stem continues to provide excellent results after extended follow-up.