The effects of anodal tDCS on pain reduction in people with knee osteoarthritis: A systematic review and meta-analysis

To synthesise the literature on the efficacy of primary motor cortex anodal transcranial direct current stimulation (M1-a-tDCS), as a standalone or priming technique, for pain reduction in people with knee osteoarthritis (KOA). The systematic literature search was conducted in MEDLINE, CINAHL, Embase and CENTRAL according to PRISMA statement. Fourteen studies involving 740 people with KOA were included. In the meta-analysis, six studies compared a-tDCS alone with sham stimulation, and five studies compared a-tDCS combined with other methods with sham stimulation. We found positive effect of a-tDCS alone on pain in KOA (standard mean difference (SMD) −0.52; 95% CI, −0.78 to −0.25; P=0.001; I2 = 69%). Further, a-tDCS with other treatments showed positive effect (SMD −1.23; 95% CI, −1.59 to −0.88; P