Transcranial direct current stimulation for knee osteoarthritis: a single-blind randomized sham-controlled trial

Abstract

OBJECTIVE\nTo evaluate the effects of transcranial direct current stimulation on pain and other symptoms of knee osteoarthritis.\n\n\nMETHODS\nWe performed a single-blind randomized sham-controlled trial with two parallel arms in an outpatient clinic of physical medicine and rehabilitation at a teaching hospital. We randomized 54 patients, 30-70 years of age, with knee osteoarthritis into two groups. They had morning stiffness ≤ 30\u202fmin, knee pain ≥ 3 months, joint crepitus, and Kellgren-Lawrence grade 1 or 2 on radiographs. For the active stimulation we administered 2\u202fmA current, 20\u202fmin for each session and for the sham group 30\u202fs stimulation and 20\u202fmin no current. Using the 10/20 International EEG system, the anode was fixed over the contralateral primary motor cortex (C3 or C4), and the cathode was placed on the ipsilateral supraorbital region (Fp1 or Fp2), with respect to the included knee. The program was repeated once daily over 5 consecutive days. Both groups received acetaminophen. We assessed the patients before and after the interventions, and three months post-intervention. The primary outcome was knee pain on the visual analog scale, and the secondary outcome was the Knee injury and Osteoarthritis Outcome Score.\n\n\nRESULTS\nThere was a statistically significant reduction in the intensity of pain within sham and active groups (both p\u202f<\u202f0.001), but no significant difference between the groups (p\u202f=\u202f0.226). Analyses of the Knee injury and Osteoarthritis Outcome Scores showed no clinically important changes.\n\n\nCONCLUSIONS\nTranscranial direct current stimulation does not reduce knee pain, does not abate other symptoms, and does not restore knee function in patients with knee osteoarthritis. The pain reduction in our study could be attributed to either placebo or the acetaminophen effect.