BONE REMODELING IN THE PROXIMAL FEMUR AFTER CHARNLEY TOTAL HIP-ARTHROPLASTY

We measured bone mineral density (BMD) in the proximal femur by dual-e nergy X-ray absorptiometry (DEXA) in 20 patients after cemented total hip arthroplasty over a period of one year. We found a statistically s ignificant reduction in periprosthetic BMD after six months on the med ial side and on the lateral side adjacent to the mid and distal thirds of the prosthesis. At one year after operation there was a mean 6.7% reduction in BMD in the region of the calcar and a mean 5.3% increase in BMD in the femoral shaft distal to the tip of the implant. These ch anges reflect a pattern of reduced stress in the proximal femur and in creased stress around the tip of the prosthesis. They support current concepts of bone remodelling in the proximal femur in response to pros thetic implantation.