PERIPROSTHETIC BONE-DENSITY AROUND FULLY HYDROXYAPATITE-COATED FEMORAL STEM

In this study, periprosthetic bone mineral density was measured at sch eduled time intervals after surgery by dual energy xray absorptiometry in 21 patients to assess the history of bone density redistribution a fter femoral stem insertion. Measurements of changes in bone density w ith time were obtained for the regions of the greater trochanter, the lateral cortex, the tip, the medial cortex, and the calcar. In all reg ions, bone density decreased during the first 3 months after surgery; this was followed by a prolonged period of 18 to 30 months of bone gai n, a subsequent period of steady state, and the final resumption of bo ne aging processes after the third postoperative year. The greatest lo ss was observed in the calcar region after 6 months (greater than 50%) . The characteristic pattern of time related bone density changes obta ined in this study may make it possible to compare other pathologic, d esign, or stiffness related patterns. This could have clinical relevan ce in the early diagnosis of pathologic processes and as a means of ev aluating prosthetic designs.