Effect of etidronate in preventing periprosthetic bone loss following cemented hip arthroplasty: a randomized, double blind, controlled trial.

Introduction: Periprosthetic bone loss occurs after insertion of a total hip prosthesis and is often a result of stress shielding or altered loading of the proximal femur. Preventing the bone loss, which may threaten the prosthesis survival, with an antiresorptive drug would be highly advantageous.

Materials And Methods: Our study investigated the effect of cyclic etidronate therapy on periprosthetic, contralateral hip, and spine bone mineral density (BMD) in a one-year, prospective, randomized, double-blind study in 31 patients after cemented hip arthroplasty. Etidronate was taken orally in a regimen repeated every 14 weeks, and periprosthetic BMD was measured with dual energy X-ray absorptiometry (DXA) in the total periprosthetic area and in the seven Gruen zones at 1 week (baseline), 6 weeks, 3 months, 6 months, and 12 months postoperatively.

Results: In the etidronate group there were significant temporal BMD decreases measured in Gruen zones 2, 3, 6, and 7 and in the entire proximal femur; the greatest decrease was 12.9% and was measured in zone 7 at six months. Also in the etidronate group, there was a significant 2.8% temporal BMD increase in the spine at 12 months. In the placebo group there were significant temporal BMD decreases measured in Gruen zones 1, 2, 3, 5, 6, and 7 and in the entire proximal femur; the greatest decrease was 25.5% and was measured in zone 7 at 12 months. There were no significant differences between the mean BMD measurements of the etidronate and placebo groups.

Conclusion: These findings suggest that cyclic etidronate therapy has no significant effect in suppressing periprosthetic bone loss after cemented hip arthroplasty.