Hydroxyapatite-coated RM cup in primary hip arthroplasty.

We reviewed 113 patients with 127 primary total hip arthroplasties using a hydroxyapatite-coated RM (Robert Mathys) cup. Average patient age was 61 (30-70) years and mean follow-up was 9.4 (6-13) years. Four patients were lost to follow-up and nine patients died of unrelated causes during the course of the study. Three acetabular components were revised; two cups were radiologically loose and one was revised for marginal erosion. No radiolucency was noted in any of the three zones in the remaining cups. There were no cases of cup migration or dislocation. The life table method predicted a 10-year survival rate of 97.9% with revision of the acetabular component for any cause as the endpoint.