Abstract Objective The aim of this systematic review and meta‐analysis is to determine the effects of transcranial direct current stimulation (TDCS) on pain (considering the different types of pain measured) and function in adults with knee osteoarthritis (OA). Literature Survey The Cochrane Library, MEDLINE, Web of Science, Embase, Scopus, Physiotherapy Evidence Database, Literatura Latinoamericana y del Caribe en Ciencias de la Salud , and Science Direct were searched from inception to December 2023. Reference lists of selected trials and previously published and cited reviews were also examined. Results were restricted to randomized controlled trials on adults with knee OA, with TDCS as the primary intervention. Studies that included other knee issues or that compared TDCS with other therapies without a control group were excluded. Methodology Study characteristics, such as author, year of publication, study design, intervention description, sample characteristics and outcomes, were described. The Cochrane risk‐of‐bias tool and the Grading of Recommendations Assessment, Development, and Evaluation system were used to assess the individual and global risk of bias and quality of evidence. To analyze the effects of the interventions on clinical outcomes, a meta‐analysis was performed. The outcomes included were self‐reported pain and function, pain pressure threshold (PPT), and conditioned pain measure (CPM). Intervention comparisons were grouped as “active TDCS” and “sham TDCS”. Synthesis A total of 1045 participants completed the interventions. The meta‐analysis demonstrated significant improvement in self‐reported pain intensity measured with the visual analogue scale or numerical rating scale (Cohen's d = −1.05 95% CI, −1.40 to −0.70), pain measured according to PPT (Cohen's d = −0.77 95% CI, −1.45 to −0.09) and function (Cohen's d = −0.29 95% CI, −0.54 to −0.04) with active TDCS as compared with sham TDCS. There was no difference in CPM between interventions. Conclusions TDCS intervention alone or in combination with other techniques improves self‐reported pain intensity (as measured by visual analogue scale, numerical rating scale, or PPT) and function in knee OA but has no impact on the endogenous pain inhibition system as measured with CPM.
Moreno‐Segura et al. (Tue,) studied this question.