Does transcutaneous electrical nerve stimulation improve the physical performance of people with knee osteoarthritis?

Background: According to a recent metaanalysis study, there is strong evidence to support the view that transcutaneous electrical nerve stimulation (TENS) is an effective treatment for managing osteoarthritis (OA) knee pain. However, there is limited evidence showing its effectiveness in improving physical function. This study examined whether TENS alone can improve physical function in terms of range of knee motion and the Timed-Up-and-Go Test. Methods: Subjects were randomly allocated into 2 groups receiving TENS at 100 Hz or a placebo TENS. Outcome measures included: 1) visual analog scale for measuring the intensity of the present pain, 2) Timed-Up-and-Go Test, and 3) range of knee motion (ROM). Repeated-measures analysis of variance and Pearson correlation were used for data analyses. Results: By day 10, TENS produced a significantly greater increase in maximum knee ROM than the placebo group (P = 0.033). TENS also significantly increased the pain-limited knee ROM across sessions, but the between-group difference was short of significance (P = 0.067). The decrease in time in performing the Timed-Up-and-Go Test was also not significantly different between the 2 groups. A moderate correlation was observed between the reduction in pain scores and the improvement in the Timed-Up-and-Go Test. Conclusions: Our findings suggested that TENS did improve some of the physical parameters but over 10 days was unable to produce significant improvement in functional performance among people with knee OA. A larger-scale study with the assessment of other functional outcomes may be required to clarify if TENS could improve function in people with knee OA. Also, exercise can be considered to be an important adjunct treatment to TENS to improve function significantly.