Context 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.