O2631 HYBRID ALUMINA TOTAL HIP ARTHROPLASTY IN PATIENTS YOUNGER THAN 55 YEARS. A 6- TO 11-YEAR EVALUATION

Aim: The aim of the study was to analyze the results of hybrid alumina prothesis using a pressþt metal backed socket and a cemented stem in young and active patients. Methods: From 1990 to 1992, 71 hybrid alumina-onalumina hip replacements were performed in 62 consecutive patients under age 55, with a mean age of 46 years at surgery. There were 56 primary procedures and 15 revision procedures. The prostheses included a cemented Ti alloy stem, a 32-mm alumina head, and a press-þt metal backed socket with an alumina insert. Results: 3 patients (4 hips) died from unrelated causes. 4 hips had revision surgery for deep infection, unexplained persistant pain, fracture of alumina head, and socket aseptic loosening. The 9-year survival rate was 93.7% if revision for any cause was the end point, and 98.4% if revision for aseptic loosening was the end point. Results in surviving patients with a minimal 5-year followup and an average followup of 8 years (57 hips) were excellent in 47 hips (82.5%), very good in 8 hips (14%), good in 1 hip and fair in one hip. 38% of the sockets had a thin and partial lucent line and 1 socket had a complete lucency less than 1mm thick. One stem had isolated femoral osteolysis. There was no detectable component migration nor acetabular osteolysis. Conclusion: Hybrid alumina prosthesis gave satisfactory results at mid term in active patients. Press-þt metal backed socket appeared as a reliable method of acetabular þxation in alumina-alumina hip replacement. Excellent results of cemented stem þxation may be related to low wear debris production.