Patients with knee osteoarthritis (OA) often rely on analgesics for pain relief. Long-term use of such treatments, however, increases the risk of adverse events. A recently published study by investigators from Italy indicates pulsed electromagnetic field therapy (PEMFT) might provide a safe and effective alternative to pharmacologic treatment.1 In the study, patients who received PEMFT for knee OA reported a significant reduction in pain and showed several other improvements compared with those receiving treatment with a sham device.
“In addition to its safety, one of the most important advantages of using pulsed electromagnetic fields is its efficacy profile, which we observed with regard to pain perception, pain threshold, and knee function,” said the study’s lead author Gian Luca Bagnato, MD, Division of Rheumatology, Department of Clinical and Experimental Medicine, University of Messina, Italy, in an e-mail interview with Rheumatology Advisor.
Previous studies assessing PEMFT for knee OA have shown conflicting results, but Bagnato and colleagues note that their results support those observed in previous high-quality randomized clinical trials. In their study, patients with radiographic evidence of knee OA and persistent pain higher than 40 mm on the visual analog scale (VAS) were randomly assigned (1:1) to receive a PEMFT wearable device that emits a safe form on non-ionizing electromagnetic radiation or a sham device that had no electromagnetic properties but was otherwise identical to the active device. Patients were required to wear the device consecutively for a minimum of 12 hours daily and to log their use of the device for 1 month, after which the safety and efficacy of treatment were evaluated.
At the end of the 1-month study period, 30 patients in each group had completed the study and were included in the assessment. Both groups reported similar average use of their respective devices (11.3 ± 0.8 h/d for the active device vs 11 ± 0.7 h/d for the sham device).
The primary outcome measure was reduction in pain intensity, as assessed through VAS and the Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores. Secondary outcome measures included quality of life, pressure pain threshold, and changes in use of nonsteroidal anti-inflammatory drugs (NSAIDs) and other analgesics.
At 1 month, patients receiving PEMFT had a 25.5% reduction in VAS pain scores, a 23.4% reduction in WOMAC pain subscale scores, and an 18.4% reduction in WOMAC total score. In comparison, those receiving the sham device had a 3.6% reduction in VAS scores and a 2.3% reduction in both WOMAC scores. The mean treatment effect observed in VAS score was -0.73 (95% confidence interval [CI], -1.24 to -0.19), whereas the effect size associated with improvement in all WOMAC subscales was -0.34 (95% CI, -0.85 to -0.17).
Among those receiving PEMFT, WOMAC assessments also showed consistent improvements in stiffness and function, changes in pressure pain threshold pointed to improved pain tolerance, and the 36-item Medical Outcomes Study Short Form version 2 revealed improved physical health but no improvements in mental health. Furthermore, 26% of patients in the PEMFT group stopped taking NSAIDs or other analgesics, whereas 3 patients (10%) in the sham device group started a new therapy to manage chronic pain and only 1 patient (3%) was able to stop taking analgesics. Neither group reported any adverse effects.
Summary and Clinical Applicability
Bagnato and colleagues’ study provides additional evidence that PEMFT may be an effective emerging treatment for knee OA; however, the study was short, had a small study population, and patients continued to use analgesics. The authors acknowledge that larger and more long-term studies are needed comparing PEMFT directly with pharmacologic approaches to better establish the role of this treatment in knee OA.
Nevertheless, Dr Bagnato believes the treatment holds promise. “The possibility of obtaining a safe and effective home-based management tool for knee OA, one of the most frequently experienced joint diseases worldwide, is very attractive,” he told Rheumatology Advisor, noting that several such devices are already available as over-the-counter (OTC) products in Europe.
In the United States, although several PEMFT devices have been approved by the US Food and Drug Administration, they are only available by prescription; however, applications for OTC clearance are being considered, Dr Bagnato noted.
1. Bagnato GL, Miceli G, Marino N, Sciortino D, Bagnato GF. Pulsed electromagnetic fields in knee osteoarthritis: a double blind, placebo-controlled, randomized clinical trial. Rheumatology (Oxford). http://rheumatology.oxfordjournals.org/content/early/2016/01/29/rheumatology.kev426.long. Published December 24, 2015. Accessed January 7, 2016.