Treatment for acetabular dysplasia using the uncemented RM acetabular component - a 20 year follow-up.

Our study reports a sub-group of patients with developmental dysplasia from a previously published larger series, with particular emphasis on the use of the uncemented RM acetabular component. We evaluated the long term results of 93 consecutive uncemented THAs in 80 patients using the titanium-coated RM acetabular component and the CLS femoral component in a prospective study. Eighteen hips in 16 patients had osteoarthritis secondary to developmental dysplasia of the hip. The mean follow-up was 19.6 years (18.2 to 20.9). Fourteen patients with 15 hips were clinically and radiographically examined and evaluated. Two patients with 3 hips died. No patient was lost to follow-up. No implant had to be revised, and no cases showed evidence of radiographic loosening. Nine acetabular components were not completely covered by host bone but this did not affect the outcome. At the latest follow-up the mean Harris Hip Score was 92 (81 to 100). The mean annual wear rate was 0.12 mm. The RM acetabular component performed well over 20 years in this selected group of patients. Complete acetabular containment was not needed, thus allowing reliable reconstruction of the anatomical centre of rotation.