Double-blind placebo-controlled trial of static magnets for the treatment of osteoarthritis of the knee: results of a pilot study.
BACKGROUND
Outpatient clinical studies of magnet therapy, a complementary therapy commonly used to treat osteoarthritis (OA), have been limited by the absence of a credible placebo control.


OBJECTIVE
Our objective was to assess the feasibility and promise of studying static magnetic therapy for knee OA and determine the ability of a new placebo-magnet device to provide concealment of group assignment.


METHODS
Randomized, double-blind, placebo-controlled clinical trial.


METHODS
Academic teaching hospital in Boston.


METHODS
We enrolled 29 subjects with idiopathic or post-traumatic OA of the knee.


METHODS
Subjects received either high-strength magnetic (active) or placebo-magnetic (placebo) knee sleeve treatment for 4 hours in a monitored setting and self-treatment 6 hours daily for 6 weeks.


METHODS
Primary outcomes were change in knee pain as measured by the WOMAC Osteoarthritis Index Pain Subscale at 6 weeks and extent of group concealment at study end.


RESULTS
At 4 hours, VAS pain scores (+/- SE) on a 5-item scale (0-500, 500 worst) decreased 79 +/- 18 mm in the active group and 10 +/- 21 mm in the placebo group (P < 0.05). There were no significant differences in any primary or secondary measure of efficacy between the treatment groups at 6 weeks. Despite widespread testing for magnetic properties, at study end, 69% of the active group and 77% of the placebo group (P > 0.2) believed that they had been assigned to the active treatment group.


CONCLUSIONS
Despite our small sample size, magnets showed statistically significant efficacy compared to placebo after 4 hours under rigorously controlled conditions. The sustained efficacy of magnetic therapy for knee osteoarthritis could be assessed in an adequately powered trial utilizing an appropriate control such our new placebo-magnet device.
Wolsko
Peter M
PM
Division for Research and Education, Harvard Medical School, Boston, MA, USA.
Eisenberg
David M
DM
Simon
Lee S
LS
Davis
Roger B
RB
Walleczek
Jan
J
Mayo-Smith
Michael
M
Kaptchuk
Ted J
TJ
Phillips
Russell S
RS
D000368:Aged; D018771:Arthralgia / Q000628:therapy*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008280:Magnetics / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000628:therapy*; D010147:Pain Measurement / Q000379:methods; D010865:Pilot Projects; D012720:Severity of Illness Index; D013997:Time Factors; D016896:Treatment Outcome