Changes of femoral periprosthetic bone mineral density 6 years after treatment with alendronate following total hip arthroplasty.

Earlier osteodensitometric results of femoral periprosthetic bone showed that postoperative antiresorptive treatment with alendronate following total hip arthroplasty (THA) reduces the periprosthetic bone loss that commonly occurs in the first months after surgery. However, whether alendronate can prevent periprosthetic bone loss over the long term, or if bone loss occurs after discontinuing alendronate is unknown. Femoral periprosthetic bone mineral density (BMD) was assessed in 49 patients 6 years after cementless total hip arthroplasty using dual energy X-ray absorptiometry. Twenty-nine patients were treated postoperatively with alendronate and 20 control patients received no treatment. All patients were followed up at 12 months after surgery in a prospective randomized study. The bone mineral density was evaluated in 7 regions of interest according to the Gruen protocol. Six years after total hip arthroplasty, no significant changes were detected in femoral periprosthetic BMD when compared with results at 1 year, and the bone loss in patients with postoperative alendronate treatment was still significantly less than those without treatment. These results suggest that the prevention of femoral periprosthetic bone loss following THA achieved by postoperative antiresorptive treatment with alendronate is of long-standing effect, and further bone loss does not occur after the first postoperative year.