Alendronate reduces periprosthetic bone loss after uncemented primary total hip arthroplasty: a prospective randomized study.

Periprosthetic bone loss, especially in the proximal part of the femur, is common after cemented and uncemented total hip arthroplasty (THA). Bone loss can be progressive and, in the extreme, may threaten survival of the prosthesis. To study whether alendronate therapy can reduce bone loss adjacent to prostheses, 13 uncemented primary THA patients were randomized to the study. They received 10 mg alendronate + 500 mg calcium (n = 8) or 500 mg calcium only (n = 5) daily for 6 months follow-up after THA. Periprosthetic bone mineral density (BMD) was measured with dual energy X-ray absorptiometry (DXA). Decreases in periprosthetic BMD in the alendronate-treated group were lower compared with the changes in the calcium-only group in the same regions of interest at the same follow-up time. In the proximal femur, the mean BMD decrease was 17.1% in the calcium-only group, whereas in the alendronate-treated group the decrease was only 0.9% (p = 0.019). The mean periprosthetic BMD change was also significantly different in the total periprosthetic area between the study groups at the end of the follow-up (calcium-only group -9.9% vs. alendronate-treated group -2.6%; p = 0.019). Alendronate therapy led to a significant reduction in periprosthetic bone loss after primary uncemented THA compared with the changes found in patients without therapy. This kind of bone response may improve the support of the prosthesis and may result in better survival of the prosthesis. However, in this study the follow-up time was too short and the study population was too small to make any long-term conclusions as to the prognosis for THA patients treated with alendronate.