Efficacy of transcranial direct current stimulation on pain intensity and functionality in patients with knee osteoarthritis: a systematic review and meta-analysis

Abstract

ABSTRACT Objective To investigate whether tDCS is superior to control groups or other interventions for pain relief and improving functionality in KOA patients. Methods PubMed, the Physiotherapy Evidence Database (PEDro), the Cochrane Library, ProQuest, and Scopus databases were searched from inception to July 2022 to identify randomised clinical trials (RCTs). The main outcomes were subjective perception of pain intensity measured either with the Visual Analogue Scale (VAS) or with the Numeric Rating Scale (NRS); and the functionality, assessed with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). As secondary outcomes, pressure pain threshold (PPT), conditioned pain modulation (CPM) and its safety were evaluated. Results We identified 10 RCTs (634 participants). The results showed an important effect favouring tDCS for pain relief [mean difference (MD) = -1.1 cm; 95% confident interval (CI), -2.1 to -0.2)] and for improving functionality [standardised mean difference (SMD) = -0.6, 95% CI, -1.02 to -0.26)]. There was also a significant improvement in PPT (MD = 0.9 Kgf/cm2, 95% CI, 0.1 to 1.6). The certainty of evidence according to GRADE was generally moderate. Conclusions Our findings suggest that tDCS is a safe treatment for reducing pain intensity, and improving functionality, and the pressure pain thresholds in patients with KOA.