Transcranial Direct Current Stimulation and Mobility Functioning in Older Adults with Knee Osteoarthritis Pain: A Double-Blind, Randomized, Sham-Controlled Pilot Clinical Study

Osteoarthritis (OA) of the knee is one of the leading causes of impaired mobility functioning. Because pharmacologic treatments may increase the risk of adverse effects, researchers are becoming interested in non-pharmacologic interventions that target central nervous system pain processing. Thus, we sought to assess the preliminary efficacy of transcranial direct current stimulation (tDCS) on mobility functioning in adults with knee OA pain. We conducted a double-blind, randomized, sham-controlled pilot clinical study in 40 community-dwelling participants who were 50−70 years old with knee OA. The participants were randomly assigned to receive either five daily sessions of 2mA tDCS for 20 minutes or sham tDCS. The anode electrode was placed over the primary motor cortex of the hemisphere contralateral to the affected knee, and the cathode electrode was placed over the supraorbital region ipsilateral to the affected knee. Mobility functioning was measured at baseline and after tDCS via a 6-minute walk test (6MWT). Participants had a mean age of 59 years (SD = 8 years), and 53% were female. After five daily sessions, the tDCS group had greater increases in the 6MWT distance (19.29 ± 5.72 meters) than the sham group (3.55 ± 7.44 meters). The mean difference between groups was 15.74 meters (t=1.68, df=38, p=.102, Cohen’s d = 0.53). Our preliminary results show that tDCS in participants with knee OA has a moderate to large effect size for improving mobility functioning. Further studies with larger samples and longer-term follow-up are needed.