Clinical study of bipolar arthroplasty *
Bipolar arthroplasty using a Kyosera ceramic; outer head and an Omnifit femoral stem was performed on 19 cases ; 5 cases with aseptic nccrosis of the femoral head, and 14 cases with osteoarthritis. Acetabulum reaming performed on 14 joints, and acctabuloplasty with a bone graft on 11 joints. Nineteen hips were followed for a mean period of 6.7 years after the arthroplasty. The patients ranged in age from 37 to 60 years old (average, 51.6 years old) at the time of the operation. Their clinical score was assessed by the hip rating score of the Japanese Orthopedic Association, which assigns a maximum of 100 points. The preoperative clinical score ranged from 17 to 81 points (mean, 44.4 points). The postoperative score improved to a range of 60 to 100 points (mean, 84.7 points). Of the 19 hips examined, 7 hips were pain-free. As measured from serial roentgenograms after the operation, the overall distance of superior migration of the prosthesis was a mean 4.1 mm. The overall distance of lateral migration of the prosthesis was a mean 2.5 mm. However migration of the prosthesis was not a clinical inconvinience. No correlation between the clinical results and the degree of acetabular migration was noted. Osteolysis was observed in only one joint around the outer head and six joints (31.6%) around the stems. Reconstruction for severe acetabular defects can be achieved successfully using this technique, but long-term follow up evaluation is needed to fully assess the role of this procedure in relation to other available options. (Accepted on October 26, 1998) Kawasaki Igakkaishi 24(4) : 221-230, 1998
