Following total hip arthroplasty (THA), femoral periprosthetic bone undergoes a remodeling process that results in bone loss in its proximal regions that may compromise the long-term outcome of THA. Periprosthetic bone loss mainly occurs during the first postoperative months. The question is whether a postoperative treatment with alendronate is effective in reducing periprosthetic bone loss and which doses and duration of treatment are required. In a 12-month prospective, randomized double-blind study, 51 patients undergoing cementless THA were treated postoperatively either with a daily dose of 20 mg alendronate for 2 months and 10 mg for 2 months thereafter (group I), with 20 mg of alendronate for 2 months and 10 mg for 4 months thereafter (group II), or treated with placebo (group III). Proximal femoral bone mineral density (BMD) was measured with dual-energy X-ray absorptiometry (DEXA) and serum biochemical markers of bone turnover bone specific alkaline phosphatase, osteocalcin, and C-terminal telopeptides (CTX-I) were assayed. Six months of alendronate treatment significantly reduced ( p < 0.001) bone loss in proximal medial region (À10%) compared with placebo (À26%). All biochemical markers of bone turnover were suppressed by alendronate. These data suggest that alendronate administered for the first 6 postoperative months following THA was effective in preventing early periprosthetic bone loss. ß

Alendronate, therefore, is capable of preventing initial periprosthetic bone loss. A dosage of 20 mg/d is required initially with daily treatment lasting at least 10 weeks.

Custom designed anatomic femoral hip stems were unable to prevent periprosthetic bone resorption. However it is concluded, that implantation of custom made stems in grossly distorted femoral anatomy induces transmission of forces similar to standard femoral stems implanted in normal medullary anatomy.

Prognostic Study, Level I (high quality prospective study-all patients were enrolled at the same point in their disease with > or = 80% followup of enrolled patients). See the Guidelines for Authors for a complete description of levels of evidence.

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