Long-term survivorship analysis of hip arthroplasty with vitallium mold cup

Cup arthroplasty was used in the initial attempts to preserve the bone stock of the femoral head and neck for hip reconstruction. However, little conclusive data are available regarding its long-term survivorship. We present a long-term survivorship analysis (mean follow-up, 19.3 years; range, 5–36.6 years) after vitallium mold arthroplasty in 77 secondary osteoarthritic hips. Kaplan–Meier survivorship analysis predicted a survival rate for vitallium mold arthroplasty of 81.6% (95% confidence interval [CI], 76.7–86.5) at 20 years and 59.1% (95% CI, 51.8–66.5) at 30 years, with conversion to total hip arthroplasty as the endpoint. The mean Merle d’Aubigné and Postel hip score showed a significant decrease in mobility from 4.12 (range, 3.18–5.86) 6 months after the operation to 3.19 (range, 1.7–4.6) at the last follow-up. No significant differences were observed for the pain score from 6 months after the operation (5.05; range, 4.2–5.9) to the last follow-up (4.46; range, 2.88–6.04)) or score for the ability to walk, from 6 months after the operation (2.5; range, 1.4–3.6) to the last follow-up (3.13; range, 1.59–4.67). Radiographically, the proximal and medial migration of the cup measured at the last follow-up was 10.4 ± 5.4mm (P < 0.01) and 0.2 ± 2.1mm (P > 0.05), respectively. Our results indicate inferior long-term survivorship after vitallium mold compared with that after Charnley low-friction arthroplasty.