Electrical Stimulation for Osteoarthritis: Does it work?

Patient having electrodes applied by a physician for transcutaneous electrical stimulation.

Knee osteoarthritis(OA) is one of the most common forms of OA. It affects over 9,000,000 million in the U.S., and its prevalence is only increasing as the population ages. Total knee replacement offers a good option for the most severe forms of OA, also known as end-stage OA, however this may not be an appropriate choice for younger patients or ones with mild to moderate OA. Furthermore, total knee replacements have a limited life span, and revision knee replacements performed on a knee that was already previously replaced have a much higher rate of complications and overall worse outcomes.

This creates a significant incentive to explore options outside of surgery in order to delay total knee replacement as much as possible.

One form of conservative management that has been used for the treatment of pain related to knee OA is electrical stimulation (ES) therapy. ES involves placement of electrodes around the painful body part, which transmit electric signals (either monophasic or biphasic) around the painful area. The theory behind this method is that nerves is electrical current to conduct messages to the brain, and the external electricity may disrupt the function of pain nerves thereby preventing the pain related signal from ever reaching the brain. Whether this truly works or not remains to be seen. ES comes in a number of different forms including transcutaneous electrical nerve stimulation (TENS), neuromuscular electrical stimulation (NMES), interferential current (IFC), pulsed electrical stimulation (PES), noninvasive interactive neurostimulation (NIN), and many others.

This modality has been tried to alleviated pain in a number of areas besides the knee including low back pain and neck pain. Studies of the use of ES in both neck and back pain showed that ES is no more effective than placebo for the treatment of those conditions. The evidence in the case of ES use for knee pain is slightly more confusion.

A meta-analysis (which combines data from multiple studies) and two reviews have been done on the topic. The recent meta-analysis by Dr. Zeng in colleagues published in the journal Osteoarthritis and Cartilage found that interferential current (IFC) was effective in alleviating pain associated with knee OA. This was supported by a Cochrane review published in 2009, the Cochrane foundation being one of the most highly respected sources of clinical reviews. However a review in 2013 found that IFC did not provide any benefit over a placebo (sham).

Similar confusing, and inconclusive, evidence is found on the use of TENS machines. Cochrane review found that there is no benefit to using these devices of pain associated with OA, however two other studies noted that a benefit may exist. It is easy to see the conundrum that faces doctors when it comes to the use of ES. The American Academy of Orthopaedic Surgeons (AAOS) could not reach a conclusion on the use of ES in knee OA, and stated that insufficient evidence exists to determine whether ES is helpful or not.

Similarly the Osteoarthritis Research Society International (OARSI) left ES out of their list of effective therapies.

While the benefits of ES are uncertain, it’s important to note that the risks are fairly low. ES is considered a fairly safe treatment modality, and the most common complaints are skin related issues. It is difficult to make any conclusive statements given the lack of evidence that ES provides pain relief for patients with OA of the knee. ES may offer marginal benefit to some people, and may help bridge the time until a knee replacement is more appropriate. On the other hand it may be an ineffective treatment modality, provide no additional benefit, in which case the cost associated with ES is not justified. Unfortunately we simply don’t have enough evidence to say at this point.

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