First there was transcutaneous electrical stimulation (TENS) – a form of electrical stimulation for relieving pain. Now, the broad category of electrical stimulation also involves stimulating muscle tissue, to strengthen muscle tissue that supports a joint in addition to relieving pain in and around the joint. This newer category is called neuromuscular electrical stimulation (NMES), and a number of studies in recent years have shown the effectiveness of NMES in electrical knee treatment, specifically on the symptoms of knee osteoarthritis (OA).

In a 2008 study published the journal Clinical Rheumatology, Turkish researchers found that a four-week program of electrical stimulation was just as effective as a four-week exercise program in relieving pain and stiffness and improving physical function (including walking time and ability to go up and down stairs) in a group of 50 women diagnosed with osteoarthritis of the knee.

The researchers concluded that electrical stimulation is a useful option for treating knee osteoarthritis, particularly in patients who are unable to perform an exercise program.

Two earlier studies by researchers in Baltimore also documented the effectiveness of electrical stimulation: knee pain reduced and quadriceps muscle strength increased in older people with osteoarthritis of the knee.

In the first of the two studies, 34 adults over age 60 with confirmed knee osteoarthritis were randomized to either NMES three days a week for 12 weeks plus education or education only. The group receiving NMES plus education showed a nine- to 11-percent increase in quadriceps strength by a number of measures, while the group who received only education saw, by some measures, a seven-percent reduction in strength over the 12-week study.

In the second study, researchers examined the short- and long-term effects of a home-based, 12-week program of NMES on knee OA pain in older adults. In this study, 38 people were assigned to one of two groups: one receiving NMES plus education, the other receiving education only. The researchers measured pain in both groups at baseline and at weeks 4, 8 and 12. Participants receiving NMES also completed a pain diary 15 minutes before and 15 minutes after each treatment.

While no significant difference in pain was seen between the groups over the course of the study, people in the NMES group did experience immediate, short-term relief, reporting There was a significant 22 percent decline in pain 15 minutes after as compared with immediately before each NMES treatment an average 22 percent decline in pain 15 minutes after treatment compared to 15 minutes before.

Electrical stimulation may ease pain and strengthen the quadriceps muscles supporting the knee. It also may delay total knee replacement.

In a recent clinical study conducted at 23 centers across the U.S., 48 men and 109 women, ranging in age from 31 to 88, with moderate-to-severe knee OA wore an FDA-approved electrical stimulation device for six to 10 hours daily (usually while sleeping). Compared to a control group of 101 patients who did not use the device, results showed that 62 percent of the people who used the electrical stimulation device postponed replacement of their knee joint for four years. Only seven percent in the control group did so.