QUANTITATIVE BONE SCANNING AFTER ASYMPTOMATIC CHARNLEY ARTHROPLASTY

To establish the normal pattern of postoperative tracer uptake we perf ormed 73 technetium-99m methylene diphosphonate scans following primar y Charnley hip replacements for arthrosis in 68 patients without clini cal, hematological and radiographic complications. The patients were d ivided into 7 subgroups according to the period, 6-24 months, between surgery and scan. There were 10-12 patients in each subgroup. A high-r esolution gamma camera with a large field of view was used. Ratios of uptake in each of 10 peri-prosthetic zones to normal bone were calcula ted. Femoral uptake was found to decrease in linear fashion from 6 to 12 months after surgery. Thereafter the uptake remained unaltered at l evels nearly twice the normal ones in the greater trochanter and nearl y 1.5 times in the lesser trochanter, returning to almost normal level s in other zones. Acetabular uptake remained elevated throughout.