A Cochrane Systematic Review of electrostimulation trials in osteoarthritis has concluded that despite twenty years of research on the use of a treatment called transcutaneous nerve stimulation (TENS) for osteoarthritis in the knee, researchers still cannot say whether it reduces pain or physical disability.

Osteoarthritis is the most common cause of pain and physical disability in older people. In TENS, a widely used form of treatment for osteoarthritis, an electrical current is applied to the skin at the joint to stimulate the nerves and try to relieve pain.

Data was reviewed from 18 small trials that together included 813 osteoarthritis patients. For physical disability, 29 out of 100 people who received TENS treatment responded to treatment, compared to 26 out of 100 people who received fake TENS treatment or took their usual treatments. There was no difference in pain relief or in the number who dropped out due to adverse effects.

"Although some people who have electrostimulation treatment for osteoarthritis of the knee show some improvement, our data suggest that this may not be greater than the improvement experienced by those who receive placebo treatment," said lead researcher, Anne Rutjes. "After two decades of research on the use of these methods there is still no clear evidence that they work."

Data was only available for a few small trials and many of these were of very poor quality. In particular, most did not provide enough information about the number of drop outs and some failed to make any mention at all of adverse effects. "To clarify the effectiveness of TENS as a treatment for osteoarthritis we need larger, better quality trials," says Rutjes.
References:
1. Anne Rutje, et al. Transcutaneous electrostimulation for osteoarthritis of the knee. Cochrane Database Syst Rev. 2009 Oct 7;(4):CD002823. PMID: 19821296.