Transcutaneous Electrical Nerve Stimulation and Interferential Current Combined with Exercise for the Treatment of Knee Osteoarthritis: A Randomised Controlled Trial

Interferential current (IFC) and transcutaneous electrical nerve stimulation (TENS) are forms of electrical stimulation frequently used to treat knee osteoarthritis (OA). The relative effectiveness of these two modalities is currently unknown. The purpose of this study was to evaluate the effects of IFC and TENS, when used in conjunction with exercise, on pain and function in patients with knee OA. Forty-six subjects with radiographically confirmed OA were randomly assigned to one of three groups: TENS and standardised exercises, IFC and exercises or exercises alone. An electrical stimulator was used to apply IFC or TENS at 80 Hz for 20 minutes. All groups had a standardised exercise programme. Treatment was applied twice per week for 4 weeks. Outcomes included a 10-point pain rating scale for pain intensity and the Western Ontario and McMaster University Osteoarthritis Index (WOMAC). A two-way repeated measures ANOVA performed on the pain assessment score showed a statistically significant effect of time (p < 0.001), but not of experimental group (p = 0.813) or interaction (p = 0.067). A similar result was obtained for WOMAC score (p < 0.001, p = 0.241 and p = 0.130 for time, group and interaction effects, respectively). All treatment protocols led to significant improvements in pain and function over time. Neither IFC nor TENS displayed significant additional effects over exercise alone.