Efficacy of different dosing schedules of etidronate for stress shielding after cementless total hip arthroplasty

Forty-four women who had undergone cementless total hip arthroplasty (THA) were selected for determination of the optimum dosage of etidronate in the treatment of stress shielding after surgery. Patients were 55-86 years of age. The patients were randomized into three groups. The control group (n = 17) was not treated with osteoactive drugs. The low-dose group (n = 12) and the high-dose group (n = 15) received 200 mg or 400 mg etidronate daily for 2 weeks, followed by 12 weeks of calcium supplementation of 500 mg/day. These patients received four cycles of therapy over 1 year postoperatively. Periprosthetic bone mineral density (BMD) was measured with dual-energy X-ray absorptiometry at 3 weeks, 6 months, and 12 months. At 12 months, bone loss in the low-dose and high-dose groups was significantly lower compared with the control group in Gruen zones 1 and 7. There were additional significant differences with regard to bone loss between the control group and the high-dose group in zones 2, 4, and 6. Our data suggest that high dosages are more effective in reducing postoperative bone loss after cementless THA.