EFFICACY OF A STATIC MAGNETIC DEVICE AGAINST KNEE PAIN ASSOCIATED WITH INFLAMMATORY ARTHRITIS

Neil Segal, Joseph Houston, M.D., Howard Fuchs, M.D., Robert Holcomb, M.D, Ph.D. and Michael J. McLean, M.D, Ph.D.

Electromagnetic fields have been used therapeutically for 2000 years, for indications ranging from headaches to gout. There is considerable evidence that steady direct current and time-variant electromagnetic fields are produced by living bone through metabolic activity and pizoelectric activity upon bone deformation respectively. Pulsed electromagnetic fields (PEMF) have been used for acceleration of fracture and osteotomy healing. These effects have been shown to be mediated by reduction of osteoclastic resorption of bone, increased vascularization and increased rate of bone formation by osteoblasts, and these mechanisms have been studied on cellular and gene transcription levels.

Placebo-controlled trials have shown decreased pain and improved functional performance in patients with osteoarthritis of the knee with PEMF therapy. However, relatively few clinical studies have examined the effects of static magnetic fields. In this study, we examined the efficacy of treatment with a static magnetic field generator as adjunctive therapy for the joint pain in patients with inflammatory arthritis.

The MagnaBloc™ (MB; U.S. patent no 5,312,321) is a non-invasive non-significant risk device, consisting of four permanent magnets arrayed with alternating polarity in a hypoallergenic plastic case. The MagnaBloc™ is approximately 3.5 centimeters in diameter, weighs approximately 30 grams and generates a magnetic field of 190 millitesla. This device reduced mechanical low back pain and knee pain significantly more than placebo. Much larger time invariant magnetic fields like those produced by magnetic resonance imaging devices have not been shown to be harmful to man or animals.

This study was designed to evaluate a protocol for use in a large double-blind, placebo-controlled study. The principal outcome measure was pain intensity in patients receiving MB therapy compared to baseline level of pain. In addition to assessment for anti-nociceptive and anti-inflammatory effects, this study also assessed the effect of MB treatment on the level of physical functioning. Volunteers for this study included patients over the age of eighteen with inflammatory arthritis (rheumatoid or psoriatic arthritis) and persistent knee pain despite appropriate use of medications.

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