Transcranial direct current stimulation combined with physical exercise in knee osteoarthritis: a protocol for a randomised controlled clinical trial.

introductionOsteoarthritis (OA) is a degenerative and progressive joint condition causing pain and disability. Physical exercise is recognised as the most effective intervention since individuals with this condition often experience muscle weakness, balance deficits and chronic pain. Additionally, knee osteoarthritis (KOA) is associated with central sensitisation, contributing to chronic pain conditions. Transcranial Direct Current Stimulation (tDCS), a non-invasive neuromodulation technique, has been employed to induce changes in pain perception by altering cortical excitability, potentially reducing chronic pain. METHODS AND ANALYSIS: This is a protocol for a randomised controlled trial. Participants will be allocated to two groups: G1 (active tDCS combined with exercise) and G2 (sham tDCS combined with exercise). The intervention protocol will last for 5 weeks, with two sessions per week on non-consecutive days. Pain intensity will be assessed as the primary outcome using the Numeric Rating Scale (NRS). The sample size was calculated based on a minimum clinically important difference of 3 points on the NRS between groups, with a statistical power of 80% and a significance level of 5%. Secondary outcomes will include physical function and global perceived change. ETHICS AND DISSEMINATION: This protocol was approved by the Research Ethics Committee of the Trairi School of Health Sciences, Federal University of Rio Grande do Norte (Approval Number: 6.801.827), and it is in accordance with the Declaration of Helsinki for human research. Results will be published in peer-reviewed journals and presented at scientific events. This trial is registered in the Brazilian Clinical Trials Registry. TRIAL REGISTRATION NUMBER: Brazilian Clinical Trials Registry (RBR-5pb2g33).