Effect of transcranial direct current stimulation at the left dorsolateral prefrontal cortex combined with quadriceps strengthening exercise in chronic knee osteoarthritis: A double-blind, randomized, sham-controlled trial

Objective To study the effect of transcranial direct current stimulation (tDCS) on the left dorsolateral prefrontal cortex (DLPFC) plus exercise on pain, function, and quality of life in chronic knee osteoarthritis. Design Thirty-two participants with chronic knee osteoarthritis were randomly assigned to real tDCS (anode: left DLPFC, cathode: right supraorbital, 2 mA for 20 minutes) or sham treatment, with quadriceps exercises three times weekly for four weeks. Visual Analog Scale (VAS), pressure pain threshold (PPT), and the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) and Short Form Health Survey-36 (SF-36), were assessed at baseline, post-treatment, and four weeks later. Results No significant differences were found between groups in any outcome after completing 12 sessions [mean difference (95% CI): VAS -0.30 (−9.49, 8.89); PPT 0.033 (−0.039, 0.105); WOMAC 4.22 (−3.35, 11.79); SF-36 − 0.44 (−6.23, 5.35)] or at follow-up [VAS 0.01 (−15.69, 15.71); PPT 0.008 (−0.113, 0.130); WOMAC 4.91 (−7.56, 17.37); SF-36 − 2.96 (−12.11, 6.20)]. Conclusions The findings showed that tDCS over the left DLPFC provided no significant additional benefit to quadriceps exercise compared to sham stimulation in improving pain, function, or quality of life in individuals with chronic knee osteoarthritis.