Influence of local exposure to static magnetic field on pain perception and bone turnover of osteoporotic patients with vertebral deformity - a randomized controlled trial.

PURPOSE: Static magnetic field (SMF) could improve pain sensation and bone turnover. In a single-center randomized double-blind placebo-controlled study we investigated the effects of SMF exposure on subjective pain and bone turnover. MATERIALS AND METHODS: Postmenopausal osteoporotic women (aged 50-70 years) with bone deformity and back pain were randomized to 10 weekly visits of 30-min SMF (n = 6) or treatment with non-magnetized pads (n = 5) on the back. Primary and secondary outcomes were changes in pain sensation on a visual analogue scale (VAS) during each visit and over 10 weeks, respectively. Tertiary outcomes were changes in osteocalcin and ß-crosslaps. SMF was inhomogeneous with 192 millitesla peak-to-peak value by 19 tesla/meter gradient of the magnetic flux density at 3 mm. RESULTS: Participants randomized to sham had higher VAS at baseline (mean difference: 2.8, 95% confidence interval (CI) 0.47-5.2 cm). Both SMF and sham similarly reduced short term pain (sham-SMF: 0.59, 95% CI - 0.31-1.49 cm, p = 0.195). VAS did not change in SMF, while it decreased in the sham group (between-group difference 0.27, 95% CI 0.04-0.50 cm/visit). Bone turnover markers remained stable. CONCLUSIONS: SMF as used in this investigation is not recommended for pain relief in postmenopausal women with vertebral deformity. The finding on long-term pain relief may relate to unbalanced randomization.