Drug Therapy Increases Bone Density in Osteonecrosis of the Femoral Head in Canines

Although many different pathogeneticmechanisms have been proposed for osteonecrosis of the femoral head, the repair process leads to structural collapse when bone resorption exceeds production. The purpose of the current study was to determine the effects of two agents with known bone-altering qualities, alendronate and simvastatin, on the healing response of a cryosurgically induced necrotic lesion of the femoral head in canines. Eighteen beagles had cryosurgical necrosis of the right femoral head. After 2 weeks, in a blinded, placebo-controlled, randomized fashion, a 10-mg dose of oral alendronate (n D 6), a 40 mg dose of simvastatin (n D 6), or a placebo (n D 6) was administered daily for 12 weeks. At sacrifice, bone densitometry and histomorphometry quantified bone in the femoral head. In the alendronate-treated animals, a 16% increase in bone mineral density of the femoral head with induced osteonecrosis was found compared with the placebo group. Increases in bone volume and trabecular thickness also were detected in the alendronate and simvastatin groups, with alendronate having the greatest effect. Clinically, increasing the amount of bone in the femoral head may forestall mechanisms leading to joint collapse characteristic of advanced osteonecrosis of the femoral head. (Journal of Surgical Orthopaedic Advances 13(4):210–216, 2004)