Immediate Effects of Transcutaneous Electrical Nerve Stimulation on Pain and Physical Performance in Individuals With Preradiographic Knee Osteoarthritis: A Randomized Controlled Trial

OBJECTIVE: To investigate the effect of transcutaneous electrical nerve stimulation (TENS) on knee pain and comprehensive physical function in preradiographic knee osteoarthritis. DESIGN: A single, participant-blinded, randomized controlled trial (RCT) with pre-post design. SETTING: University research laboratory. PARTICIPANTS: Patients with knee pain belonging to Kellgren-Lawrence grade 0 or 1 (N=50; aged 50-69y) were randomly assigned to the TENS (n=25) and sham-TENS groups (n=25). INTERVENTIONS: All participants wore the TENS device under the patella of the symptomatic knee. After measurement, the TENS devices in the TENS group were turned on, and those in the sham-TENS group were not connected. MAIN OUTCOME MEASURES: The primary outcome measures included the stair climb test, timed Up and Go (TUG) test, 6-minute walk test (6MWT), and knee pain evaluated using the visual analog scale (VAS) for stair climb test, TUG test, and 6MWT. Secondary outcomes included knee extensor strengths and the 2-step test and stand-up test from the locomotive syndrome risk test. RESULTS: Multiple regression analysis revealed that TENS intervention significantly improved the walk distance and VAS score of the 6MWT, after adjusting for premeasurement data (distance; P=.015, VAS; P=.030). CONCLUSIONS: Use of TENS improved the VAS score for pain and the distance walked in the 6MWT for individuals with Kellgren-Lawrence grade 0 or 1 of the knee. Thus, TENS may be effective for long-distance walking in patients with preradiographic knee osteoarthritis.