Clinical results and wear performance of bipolar hip endo prosthesis with alumina outer head and alumina inner head inserted for rheumatoid patients

摘要

Fifteen patients (20 hip joints) with rheumatoid arthritis, who underwent hip arthroplasties using alumina-made bipolar endoprosthesis with or without bone graft, were evaluated clinically and roentgenographically. They were followed at least for five years (range; 5-9 ys). Average hip scores improved from 32 to 72 postoperatively. According to the roentgenographic analysis, osteolysis as well as aseptic loosening of femoral components was not observed in all of the hip joints. Although proximal migration of the outer head was seen in all of the hip joint, that was not progressive in seven out of the 20 hips. In addition, the proximal migration did not affect hip scores as well as patients' daily function. One hip joint was revised due to the breakage of alumina inner head. Average linear wear rate of polyethylene insert was 0.07 mm/year according to the computer digital analysis. The results of the present study suggests that alumina-made bipolar endoprosthesis may be an alternative to total hip arthroplasty for rheumatoid patients because of low wear performance and less invasive surgery.