Cementless total hip arthroplasty with the rectangular titanium Zweymüller stem: a concise follow-up, at a minimum of twenty years, of previous reports.

In 2002 and 2006, we reported the long-term results of 208 total hip replacements performed with the Zweymüller stem and a threaded cup in 200 patients. The present study gives an update on this patient cohort. At a minimum of twenty years postoperatively, seventy-three patients (seventy-five hips) were available for follow-up; twelve patients were lost to follow-up. The key findings of our previous reports were the absence of aseptic femoral stem loosening and a poor rate of survival of the threaded cup. Since then, two revisions have been performed because of aseptic stem loosening. We observed osteolytic lesions around the proximal part of the femoral component on twenty-four (47%) of fifty-one radiographs, but no stem was deemed at risk for loosening. The probability of survival of the stem at twenty years was 0.96 (95% confidence interval, 0.91 to 0.99), and the probability of survival of the cup at twenty years was 0.67 (95% confidence interval, 0.57 to 0.75). The Zweymüller femoral stem, a tapered, rectangular implant, continues to give excellent long-term results.