Bipolar permanent magnets for a pilot study
Chronic low back pain is one of the most prevalent and costly medical conditions in the United States. Permanent magnets have become a popular treatment for various musculoskeletal conditions, including low back pain, despite little scientific support for therapeutic benefit. OBJECTIVE: To compare the effectiveness of 1 type of therapeutic magnet, a bipolar permanent magnet, with a matching placebo device for patients with chronic low back pain. DESIGN: Randomized, double-blind, placebo-controlled, crossover pilot study conducted from February 1998 to May 1999. SETTING: An ambulatory care physical medicine and rehabilitation clinic at a Veterans Affairs hospital. PATIENTS: Nineteen men and 1 woman with stable low back pain of a mean of 19 years' duration, with no past use of magnet therapy for low back pain. Twenty patients were determined to provide 80% power in the study at P<.05 to detect a difference of 2 points (the difference believed to be clinically significant) on a visual analog scale (VAS). INTERVENTIONS: For each patient, real and sham bipolar permanent magnets were applied, on alternate weeks, for 6 hours per day, 3 days per week for 1 week, with a 1-week washout period between the 2 treatment weeks. MAIN OUTCOME MEASURES: Pretreatment and posttreatment pain intensity on a VAS; sensory and affective components of pain on the Pain Rating Index (PRI) of the McGill Pain Questionnaire; and range of motion (ROM) measurements of the lumbosacral spine, compared by real vs sham treatment. RESULTS: Mean VAS scores declined by 0.49 (SD, 0.96) points for real magnet treatment and by 0.44 (SD, 1.4) points for sham treatment (P = .90). No statistically significant differences were noted in the effect between real and sham magnets with any of the other outcome measures (ROM, P = .66; PRI, P = .55). CONCLUSIONS: Application of 1 variety of permanent magnet had no effect on our small group of subjects with chronic low back pain.