[Cementless cup anchorage in hip endoprostheses. Comparative study of 3 cup systems with titanium surface]

A wealth of commercially available hip endoprotheses makes it difficult for the practitioner to choose the best implant for each individual case. In a multi-centre study, in which 22 hospitals took part, a cementless stem was used 1172 times and was combined with 3 different cementless cup components. The follow up period ranged from 1-8 years. In 321 cases the spherical Mecring cup, in 208 cases the spherical CLS-expansion cup and in 643 cases the conical Weill-ring was implanted. The predominant indication for the THR was primary coxarthrosis (767 patients). Evaluation of clinical results was based on the Merle d'Aubigné score. Good or excellent results were found in 82% for the Mercring, in 85% for the Weill-ring and in 91% when the CLS-expansion cup was used. Whereas 88% of the patients with the Mecring or Weill-ring had minimal or no pain, 94% of the patients had minimal or no pain when the CLS-expansion cup was implanted. Aseptic loosening was found in 1.25% for the Mecring and 1.5% with the Weill-ring. In the CLS-expansion cup group, 2 cases with radiological signs of loosening were seen, but neither patient required revision. The CLS-expansion-cup with the press fit system shows better medium follow-up results in this study, than the Mecring or Weill-ring systems.