Archives of Physical Medicine and Rehabilitation. 2001 Oct;82(10):1453-60
Two Configurations of Static Magnetic Fields for Treating Rheumatoid Arthritis of the Knee: A Double-Blind Clinical Trial
Segal NA, Yoshitaka T, Huston J, Saeki Y, Shimizu M, Fuchs H, Shimaoka Y, Holcomb RR, McLean MJ
INTRODUCTION
RHEUMATOID ARTHRITIS (RA) is a disabling disease that limits patients’ mobility, hampers work, and reduces patients’ quality of life. Joint pain and inflammation, as well as patients’ and physicians’ assessment of disease activity and physical functioning, are used as indices of the effectiveness of treatments. Pharmacologic agents commonly used in the treatment of RA are often costly, and possess numerous potentially toxic side effects that limit their use with many patients.
In older patients, chronic use of nonsteroidal anti-inflammatory drugs is associated with a high frequency of adverse effects. Treatment with corticosteroids, other immunosuppressants, or disease-modifying anti-rheumatic drugs may result in harmful metabolic, renal, or pulmonary side effects, necessitating expensive laboratory monitoring. Minimizing toxic side effects and treatment costs is as important as therapeutic efficacy in identifying useful new treatment modalities.
Electromagnetic fields have been used therapeutically for 2000 years for a wide range of indications. Placebo-controlled trials with pulsed electromagnetic field therapy have shown decreased pain and improved functional performance in patients with osteoarthritis of the knee. There have also been reports of the use of static magnetic fields in treating fibromyalgia, postoperative and traumatic wound pain, and ligamentous injuries, but such studies cannot generally be found in the peer-reviewed medical literature. There have also been some placebo-controlled studies that demonstrated no significant relief of exercise-induced muscle pain7 or low back pain (LBP).
The magnetic fields produced by the devices used in these studies had a tissue penetration of 1 to 3mm, which may not have been sufficient to have effected pain generators. In contrast, pilot studies have suggested that certain static magnetic fields, with deeper tissue penetration, may be efficacious in the treatment of localized pain in postpoliomyelitis syndrome, diabetic neuropathic leg pain, chronic mechanical LBP (also, Holcomb et al, unpublished data) and mechanical knee pain, as well as pain secondary to RA of the knee.
There is also evidence that inflammatory synovitis, induced in the hind joints of rats, can be significantly suppressed by exposure to a static magnetic field. With increasing evidence that both symptomatic pain and the pathologic cellular immune response in arthritic joints can be significantly suppressed with the use of static magnetic fields, larger randomized, double-blind, controlled clinical trials to assess the therapeutic efficacy of static magnetic fields are needed. Such trials will help in accurately assessing the effect of magnetic field therapy, which differs from pharmaceutical assessment.
This randomized, double-blind, controlled, multisite clinical trial was initiated to examine the efficacy of a novel magnetic treatment device as adjunctive therapy for knee pain in patients with RA. Principal outcome measures included patients’ reported pain intensity during MagnaBloc™ therapy,a as recorded in a pain diary, compared with their initial level of pain. Previous studies have not adequately examined the duration of the effect after application of a magnetic field. Thus, the degree, rapidity of onset, and the duration of relief were also assessed.
The study was also aimed at determining whether the level of physical functioning increased in patients who received MagnaBloc therapy as compared with those treated with control devices. The MagnaBloc is a noninvasive device with no known significant risks. Pilot studies support its efficacy in treating mechanical LBP, as well as pain secondary to RA of the knee. The magnetic field produced by the MagnaBloc reversibly blocks action potential firing by adult dorsal root ganglion cells in monolayer cell culture.