Fixation of cemented acetabular prostheses. The influence of preoperative diagnosis.

The authors evaluated the fixation of cemented acetabular prostheses in patients with osteoarthritis (20 hips), rheumatoid arthritis (15 hips), and sequelae after fracture of the femoral neck (13 hips) using roentgen stereophotogrammetric analysis. The three-dimensional displacements of the cups were measured during the first 2 postoperative years, and radiographs were examined to assess bone quality, containment, inclination, and area of cement surrounding the cups. There was a greater proportion of migrating cups in patients with rheumatoid arthritis and fracture of the femoral neck compared with osteoarthritis. Patients with poor bone quality according to the modified Engh index, small cement area surrounding the cups, and cups with small inclination displayed increased frequency of migration.