Electromagnetic effects on forearm disuse osteopenia: a randomized, double-blind, sham-controlled study.

A randomized, double-blind, sham-controlled, feasibility and dosing study was undertaken to determine if a common pulsing electromagnetic field (PEMF) treatment could moderate the substantial osteopenia that occurs after forearm disuse. Ninety-nine subjects were randomized into four groups after a distal radius fracture, or carpal surgery requiring immobilization in a cast. Active or identical sham PEMF transducers were worn on the distal forearm for 1, 2, or 4 h/day for 8 weeks starting after cast removal ("baseline") when bone density continues to decline. Bone mineral density (BMD) and bone geometry were measured in the distal forearm by dual energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT) at entry ("baseline") and 8, 16, and 24 weeks later. Significant average BMD losses after baseline were observed in the affected forearm at all time points (5-7% distally and 3-4% for the radius/ulna shaft). However, after adjusting for age, gender, and baseline BMD there was no evidence of a positive effect of active versus sham PEMF treatment on bone loss by DXA or pQCT for subjects completing all visits (n = 82, ∼20 per group) and for an intent-to-treat analysis (n = 99). Regardless of PEMF exposure, serum bone-specific alkaline phosphatase (BSAP) was normal at baseline and 8 weeks, while serum c-terminal collagen teleopeptide (CTX-1) was markedly elevated at baseline and less so at 8 weeks. Although there was substantial variability in disuse osteopenia, these results suggested that the particular PEMF waveform and durations applied did not affect the continuing substantial disuse bone loss in these subjects.