The Zweymüller cementless total hip prosthesis in patients aged 50 years and younger

Sixty-eight young patients (74 prostheses), mean age 43 years (standard deviation 7.7) at the time of the index operation, with a Zweymüller cementless total hip prosthesis were evaluated with a mean follow-up time of 75 months (SD 15.7). At follow-up, the mean Harris Hip Score was 94 (SD 8.1). Six stem prostheses had vertical subsidence and nine cups showed signs indicating possible loosening. The Oxford Hip Score averaged 19 points (SD 8.7). Revision surgery was performed for septic loosening (n=3 stem and cup prostheses), for aseptic loosening of the cup (n=2), and for a traumatic periprosthetic fracture (n=1 stem). Worst case survival analysis for aseptic loosening of the cup showed a probability for revision of 3% (CI₉₅ 0 – 7.2%) with a cumulative survival of 96% (CI₉₅ 100 – 90.3%) after 84 months. For the stem prostheses the probability for revision was 1% (CI₉₅ 0 – 4.3%) after 114 months with a cumulative survival of 99% (CI₉₅ 100 – 95.8%) after 72 months. Worst case cumulative survival for any reason of revision was 94.5% (CI₉₅ 99.9 – 89.2%) after 81 months. Promising results of the Zweymüller cementless hip prosthesis for the younger patient were obtained, although longer follow-up will be necessary.