Instability, migration and laxity of total hip prostheses. A roentgen stereophotogrammetric study.

Roentgen stereophotogrammetric analysis was used in the evaluation of clinical and/or radiographic problems in 28 total hip replacements without suspicion of infection. Instability of the acetabular and/or the femoral component was revealed in 14 cases. In 21 cases, examined twice, migration of the acetabular component was found in eight cases and migration of the femoral component in 15 cases. The method allows instability and migration of the prosthetic components as well as joint laxity to be determined with a high degree of accuracy.