A good quality, positive trial of pulsed electromagnetic fields for knee osteoarthritis

PainSci » bibliography » Bagnato et al 2016
updated Jan 6, 2018

Tags: arthritis, knee, electrotherapy, good news, aging, pain problems, leg, limbs, devices, treatment

Two pages on PainSci cite Bagnato 2016: 1. Zapped! Does TENS work for pain? 2. TENS has a complicated, awesome cousin: pulsed electromagnetic field therapy

PainSci commentary on Bagnato 2016: ?This page is one of thousands in the PainScience.com bibliography. It is not a general article: it is focused on a single scientific paper, and it may provide only just enough context for the summary to make sense. Links to other papers and more general information are provided wherever possible.

This was a rigorous test of wearable pulsed electromagnetic fields (PEMF) for older patients with osteoarthritis of the knee: moderate to severe cases with X-ray evidence and pain of at least 4/10 for more than six months, despite maximum tolerated medication. Sixty patients wore either a real PEMF device for 12 hours per day, or a fake; neither they nor the researchers knew who got real PEMF (double-blind). PEMF is particularly easy to test properly, because it causes no sensation, making it much easier to compare to an active placebo.

The placebo devices do not emit a radiofrequency electromagnetic field but are identical to the active devices, including a light-emitting diode light showing operation. The energy from the active device is not felt by the user, and the active device cannot be distinguished in any way from the placebo device.

Their pain and knee function were compared. PEMF won decisively: the real-PEMF patients enjoyed a 25.5% reduction in pain, compared to a 3.6% reduction for the fake-PEMF patients. Knee function improved as well, though not as much. I hope everyone got a real PEMF device at the end!

That’s compelling evidence. Not that there aren’t caveats. There are always caveats.

Although the results seem straightforwardly positive, the authors explain that “some of the effects of this therapeutic approach might be derived from neuromodulation of the pain mechanism”: that is, it might be “just” a pain-killer, as opposed to actually helping to heal arthritic cartilage. (But killing pain effectively would be a pretty good second place.)

Also, the device used is extremely low-power (a tiny battery) — so low that it's quite implausible that it could possibly have a therapeutic effect, and these results need replication to be believed, no matter how good the study seems.

The Bioelectronics Corporation manufactures PEMF devices, and provided the pulsed electromagnetic fields and placebo devices, but they did not fund the study and the authors declared no conflict of interest. These devices are widely available to consumers: see ActiPatch®.

~ Paul Ingraham

original abstract †Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

OBJECTIVES: This trial aimed to test the effectiveness of a wearable pulsed electromagnetic fields (PEMF) device in the management of pain in knee OA patients.

METHODS: In this randomized [with equal randomization (1:1)], double-blind, placebo-controlled clinical trial, patients with radiographic evidence of knee OA and persistent pain higher than 40 mm on the visual analog scale (VAS) were recruited. The trial consisted of 12 h daily treatment for 1 month in 60 knee OA patients. The primary outcome measure was the reduction in pain intensity, assessed through VAS and WOMAC scores. Secondary outcomes included quality of life assessment through the 36-item Medical Outcomes Study Short-Form version 2 (SF-36 v2), pressure pain threshold (PPT) and changes in intake of NSAIDs/analgesics.

RESULTS: Sixty-six patients were included, and 60 completed the study. After 1 month, PEMF induced a significant reduction in VAS pain and WOMAC scores compared with placebo. Additionally, pain tolerance, as expressed by PPT changes, and physical health improved in PEMF-treated patients. A mean treatment effect of -0.73 (95% CI - 1.24 to - 0.19) was seen in VAS score, while the effect size was -0.34 (95% CI - 0.85 to 0.17) for WOMAC score. Twenty-six per cent of patients in the PEMF group stopped NSAID/analgesic therapy. No adverse events were detected.

CONCLUSION: These results suggest that PEMF therapy is effective for pain management in knee OA patients and also affects pain threshold and physical functioning. Future larger studies, including head-to-head studies comparing PEMF therapy with standard pharmacological approaches in OA, are warranted.

original abstract †Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

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