Langzeitergebnisse zementfreier Hüftvollprothesen (Zweymüller)

Aim of the study: The purpose of the study is the evaluation of subjective, clinical and radiological long-term results of cementless total hip replacements with Zweymuller stems and various cups. Method: 113 of 165 consecutively implanted Zweymuller stems have been examined clinically and radiologically as well as assessed for subjective satisfaction by questionnaire, 26 additional patients were analysed by questionnaire only. Thus, the follow-up rate is 85.5% with a mean follow-up period of 8.9 years (range 5-12.2 years) as far as evaluation of subjective information including data on failures is concerned. The follow-up results were rated by the scores of Merle d'Aubigne and Harris and radiolucent lines on the X-rays were analysed. Results: 96% of the analized patients stated subjective satisfaction. 101 hips caused no or only little pain. The average Harris Hip Score rose from 47.1 preoperative to 86.8 postoperative, the functional value of Merle d'Aubigne rose from 4.9 to 10.1 (maximum 12 points). The survival rate of the stems after 10 years is 96%, the complication rate is very low. 81% of the stems showed a proximal radiolucent line. 3 different kinds of cups were used, 79% of the polyethylene cups and 8% of the titanium cups, respectively, were loosened or had been explanted at the time of examination. Conclusions: During an observation period of 12 years, the implantation of the Zweymuller stem has very successful results. The proximal radiolucent lines should nevertheless cause concerns about the predominantly distal anchoring of the stem. The long-term survival of the stems is much better than that of the titanium cups.