Bone scans in patients with osteoarthritis of the hip for the evaluation of bipolar hip arthroplasty: quantitative analysis using SPECT

To establish the time-course of bone scans after bipolar hip arthroplasty (BHA) bone scanning was performed before and after surgery in 22 hips. The influence of migration of the outer head into the acetabulum on the time-course of bone scans was examined by analyzing the relationship between the uptake of radioisotope and the magnitude of migration. The bone scans were quantitatively analyzed by single photon emission computed tomography (SPECT) on the basis of the ratio of radioactivity at the acetabulum to that in the anterior superior iliac spine (ASIS). The increased radionuclide activity decreased exponentially to a baseline with time after surgery. The postoperative uptake ratio could be expressed as a function of the preoperative uptake ratio and the postoperative length of time. The regression slope representing the decreasing rate of uptake showed no significant differences between two groups divided by the magnitude of migration of the outer head. Migration of the outer head was considered not to influence the time-course of the bone scans.