Osteoarthritis and Electromagnetic Field Therapy

Long popular in Japan, magnet therapy has entered public awareness in the United States.

Read more details about Electromagnetic Field Therapy.

Several double-blind, placebo-controlled studies suggest that pulsed electromagnetic field therapy, a special form of magnet therapy, can improve symptoms of osteoarthritis.^112-115

One small study provides extremely weak supporting evidence for the more ordinary form of magnet therapy: static magnets.¹²⁴

A subsequent much larger study of static magnets failed to find real magnets more effective than placebo magnets, but a manufacturing error may have obscured genuine benefits (some people in the placebo group were accidentally given active magnets).¹⁴⁹

In yet another placebo-controlled trial, the use of a magnetic knee wrap for 12 weeks was associated with a significant increase in quadriceps (thigh muscle) strength in patients with knee osteoarthritis.²⁰¹

Many commercial magnets have such a weak field that it is hard to believe they could affect the body at all. Some, however, are quite powerful and could conceivably cause effects at some depth. (The moving magnetic fields of rTMS and pulsed electromagnetic therapy [PEMF] act differently, and there is little doubt that they can affect nerve tissue and possibly other parts of the body as well.)

A commonly held misconception is that magnets attract the iron in blood cells, thus moving the blood and stimulating circulation. However, the iron in the blood is not in a magnetic form. Static magnets could affect charged particles in the blood, nerves, and cell membranes or subtly alter biochemical reactions, although whether the effect is strong enough to make a difference remains to be shown.¹

1. Frankel R, Liburdy R. Biological effects of static magnetic fields. In: Polk C, Postow E, eds. Handbook of Biological Effects of Electromagnetic Fields. 2nd ed. Boca Raton, FL: CRC Press; 1996.

112. Trock DH, Bollet AJ, Dyer RH Jr, et al. A double-blind trial of the clinical effects of pulsed electromagnetic fields in osteoarthritis. J Rheumatol. 1993;20:456-460.

113. Trock DH, Bollet AJ, Markoll R. The effect of pulsed electromagnetic fields in the treatment of osteoarthritis of the knee and cervical spine. Report of randomized, double blind, placebo controlled trials. J Rheumatol. 1994;21:1903-1911.

114. Jacobson JI, Gorman R, Yamanashi WS, et al. Low-amplitude, extremely low frequency magnetic fields for the treatment of osteoarthritic knees: a double-blind clinical study. Altern Ther Health Med. 2001;7:54-60,62-64,66-69.

115. Nicolakis P, Kollmitzer J, Crevenna R, et al. Pulsed magnetic field therapy for osteoarthritis of the knee—a double-blind sham-controlled trial. Wien Klin Wochenschr. 2002;114:678-684.

124. Wolsko PM, Eisenberg DM, Simon LS et al. Double-blind placebo-controlled trial of static magnets for the treatment of osteoarthritis of the knee: results of a pilot study. Altern Ther Health Med. 2004;10:36-43.

149. Harlow T, Greaves C, White A, et al. Randomised controlled trial of magnetic bracelets for relieving pain in osteoarthritis of the hip and knee. BMJ. 2004;329:1450-1454.

201. Chen CY, Chen CL, Hsu SC, et al. Effect of magnetic knee wrap on quadriceps strength in patients with symptomatic knee osteoarthritis. Arch Phys Med Rehabil. 2008;89:2258-2264.