Total hip arthroplasty using an alkali- and heat-treated titanium Zweymüller stem with no trochanteric shoulder: results at 5-year follow-up.

ABSTRACT

BACKGROUND: A trochanteric shoulder is 1 of the characteristics of the original Zweymüller femoral stem for total hip arthroplasty (THA). There have been few clinical reports of THA using recently available versions of Zweymüller-type stems with eliminated trochanteric shoulder. METHODS: 82 consecutive THAs with a Zweymüller-type stem without trochanteric shoulder were analyzed. The stem was made of alkali- and heat-treated titanium, straight, tapered, with rectangular cross-section. Survivorship was estimated with the Kaplan-Meier method. RESULTS: 76 of 82 hips (92.7%) were followed for more than 5 years or until revision. 35 of 82 hips (42.7%), were revised and the predominant reason for revision was aseptic loosening of the femoral stem (34 of 35 hips, 97.1%). Survival with revision for any reason as the endpoint was 71.3% (95% CI, 51.8% to 80.1%) at 5 years. CONCLUSIONS: The survival of the modified Zweymüller-type stem with no trochanteric shoulder was unacceptably low.