Purpose: Pulsed electromagnetic fields (PEMF) have been employed for treatment of knee Osteoarthritis (OA) with varied success. PEMF signals have been shown to modulate CaM-dependent signaling pathways that orchestrate the release of cytokines and growth factors in cellular responses to injury. This study was designed to determine if PEMF configured to modulate CaM/NO/cGMP signaling would reduce pain in early knee OA.
Methods: This IRB approved double-blind, placebo-controlled, randomized pilot study used VAS pain scores on a 0-10 cm scale with respect to baseline as an outcome measure for each cohort. Patient selection was knee pain for at least 3 months with an imaging study confirming cartilage loss, an initial VAS score ≥ 4, and at least 2 hours of daily standing activity in a physical occupation. Patients with rheumatoid arthritis, gout, pregnancy, cortisone injections, surgery, or viscosupplementation were excluded. The PEMF signal consisted of a 7 msec burst of 6.8 MHz sinusoidal waves repeating at 1burst/sec delivering a peak induced electric field of 34 ± 8 V/m in the knee. The light-weight portable battery operated device was used 15 minutes twice daily, andcould be easily placed over the knee with clothing. Blinding was maintained because this PEMF can only be detected with specialized equipment. Un-blinding occurred after all data was collected. Patients self-reported maximum daily VAS pain scores on an unmarked horizontal 10 cm line (0 = no pain, 10 = worst possible pain) at baseline (day 0), daily for the first 14 days and from day 29 to day 42. Results were analyzed using the Student's t-test or one way repeated measures ANOVA with Holm-Sidek post hoc analysis, as appropriate. Significance was P ≤ 0.05. Data is displayed ± SEM.
Results: There were no adverse effects and the devices were well tolerated. There were no significant baseline differences in mean age, body mass index (BMI), or Kellgren-Lawrence (K-L) radiographic scores, between active and sham cohorts. Thirty four patients started treatment. Of these, 19 (14F, 5M) were shams, and 15 (10F, 5M) were actives. All enrolled patients received PEMF treatment to day 14. Thereafter, 3 active and 7 sham patients dropped out of the study by day 42, citing lack of perceived benefit as the reason, confirmed by VAS scores. The PEMF signal caused 50% ± 11% decrease in mean maximum VAS vs mean baseline VAS for the treated group on day 1, persisting to day 42 (P < 0.001). There was no significant decrease in mean maximum VAS in the sham group (P = 0.227). The overall decrease in VAS scores from baseline was 2.7 ± 0.57 (P < 0.001) for the active group vs 1.5 ± 0.41 (P = 0.168) for the sham group. There was no significant difference in mean start VAS between active and sham groups.
Conclusions: This non-thermal, non-invasive PEMF, when configured to dose CaM/NO/cGMP signaling, has a significant and rapid impact on pain from early knee OA. The PEMF effect on pain is consistent with the known rapid effect of NO signaling on reduction of effusion. The intervention is novel because it is non-pharmacological, and the patient population did not have end stage OA and was required to be on their feet at least two hours a day.
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