Clinical and motion studies of the Bateman bipolar prosthesis in osteonecrosis of the hip

Forty-seven hips in 38 patients with femoral head osteonecrosis were reviewed for a mean follow-up period of 2.6 years. The average preoperative Harris hip score was 24.7; postoperatively, the average score was 84.5. Cineroentgenographic motion studies were carried out on 14 hips and revealed motion at both the inner and outer bearing up to seven years postoperatively. In the unloaded mode, inner- and outer-bearing motion were equal. In the weight-bearing position, inner-bearing motion increased significantly while outer-bearing motion decreased. Only one case of acetabular wear or protrusio was noted.