Effects of spatially targeted transcutaneous electrical nerve stimulation using an electrode array that measures skin resistance on pain and mobility in patients with osteoarthritis in the knee: a randomized controlled trial

Abstract

A novel device was developed that measured local electrical skin resistance and generated pulsed local electrical currents that were delivered across the skin around the knee for patients with osteoarthritis (termed eBrace TENS). Currents were delivered using an electrode array of 16 small circular electrode elements so that stimulation could be spatially targeted. The aim of this study was to investigate the effects of spatially targeted transcutaneous electrical nerve stimulation (TENS) to points of low skin resistance on pain relief and mobility in osteoarthritis of the knee (OAK). A randomised, controlled, 3-arm, parallel-group trial was designed that compared pain and function following a 30 to 45 minute intervention of TENS at specific locations depending on the local electrical skin resistance. Pain intensity by the visual analogue scale (VAS), 6-minute walk test, maximum voluntary contraction (MVC), and range-of-motion (ROM) were the primary outcomes. Lowest-resistance TENS reduced pain intensity during walking relative to resting baseline compared with random TENS (95% confidence interval of the difference: -20.8mm, -1.26 mm). There were no statistically significant differences between groups in distance during the walk test, maximum voluntary contraction (MVC) or range-of-motion (ROM) measures or WOMAC scores. In conclusion, we provide evidence that use of a matrix electrode that spatially targets strong nonpainful TENS for 30 to 45 minutes at sites of low resistance can reduce pain intensity at rest and during walking.