The effect of alendronate on bone mass after distal forearm fracture

Fracture and immobilization of an extremity lead to bone loss at the fractu re and at adjacent sites. We conducted a 1-year, single-center, prospective , randomized, double-blind study to determine whether bone loss would occur in the distal radius after a Colles' fracture and whether this loss could be prevented using an antiresorptive drug (alendronate). Thirty-seven women with a recent fracture of the distal forearm and low bone mineral density (BMD) of the lumbar spine were randomized to receive either 10 mg alendrona te daily err placebo. BMD of both forearms was measured at baseline and aft er 3, 6, and 12 months. The results of four women who developed reflex symp athetic dystrophy were not included in the analysis. In the placebo group, there was a significant reduction at 3 months and 6 months in BMD of total radius (p < 0.01), one-third distal radius (p < 0.01), middistal radius (p < 0.05), and ultradistal radius (p < 0.01) on the fractured side. The loss in BMD at one-third distal radius remained significant at month 12 (p less than or equal to 0.001). In the alendronate group BMD of total distal radiu s, one-third distal radius, and middistal radius at the fractured side rema ined unchanged. BMD of ultradistal radius increased significantly at months 3, 6, and 12, compared with baseline (p < 0.05). The difference between th e two treatment groups was significant at 3 months and 6 months and borderl ine significant (p = 0.054) after 1 year in total distal radius. In ultradi stal radius the differences were significant at all time points. We conclud e that BMD of the distal radius of a recently fractured forearm decreases s ignificantly in the 6 months after fracture and the resulting deficit remai ns evident at least 1 year after fracture. This bone loss can be prevented by alendronate.