Bone Loss Around 2 Different Types of Hip Prostheses

Dual energy x-ray absorptiometry (DXA) allows the measurement of bone mineral density (BMD) around an uncemented hip prosthesis. The aims of this study were: 1) to determine the reproducibility of periprosthetic BMD measurements; 2) to delineate the time course of bone loss that occurs after insertion of a hip prosthesis; and 3) to compare the bone loss around two different types of hip prosthesis. We studied 20 patients: 11 had Bateman and 9 had porous-coated anatomic prostheses inserted. The mean bone loss in 20 patients between 6 and 52 weeks after surgery was 6%. The greatest loss during this period was 18% and occurred from the proximal medial cortex. We conclude that measurement of periprosthetic bone mass by DXA is a precise technique. Bone loss was rapid in the first 6 months following total hip replacement. There was no difference in the bone loss occurring around the two prostheses studied.