Microcurrent therapy in the treatment of knee osteoarthritis. Could it be more than a placebo-effect? A randomized controlled trial.

BACKGROUND: Microcurrent therapy (MCT) is a novel electrotherapy modality with very low current-levels that may reduce pain especially in joints and muscles. AIM: To explore potential effects of MCT on pain in patients with knee osteoarthritis, to explore effects of different treatment parameters and to distinguish them from placebo-effects. DESIGN: Randomized four arms controlled clinical trial. SETTING: Outpatient tertiary medical care center. POPULATION: 56 patients with knee OA (K&L-Score II or III), 14 male and 38 female, mean age: 71.7 (+/- 7.3), pain intensity higher than NRS 3 from 10. METHODS: Patients were randomized into four groups: MCT with 100 muA (group A), MCT with 25 muA (group B), sham-treatment (group C) and a control-group without intervention. Treatment groups received 10 sessions of MCT for 30 min each over a period of 22 days. The primary outcome was daily pain intensity throughout the treatment period measured by a NRS from 0-10. Second outcome measurements were the KOOS (Knee Osteoarthritis outcome score), the SF-36-Questionnaire, the 6-min-walking-test and the Get-up-and-go-test. RESULTS: Evening pain was reduced significantly in the verum-groups compared to sham group (Group A vs. Group C: p < 0.001, Group B vs. Group C: p= 0.006) and to no intervention (Group A vs. Group D: p< 0.001, Group B vs. Group D: p=0.002). The difference between sham-therapy and no therapy was not significant. In the pre-post analysis of the KOOS group A improved significantly in the subscale Symptoms. Group A and B and D improved in the subscale ADL. CONCLUSIONS: The results of this RCT suggest that MCT has beneficial effects on pain in patients with knee osteoarthritis that are not explained by a placebo effect. Due to the explorative, pilot character of the study, further confirmation is needed before clear recommendations can be given. CLINICAL REHABILITATION IMPACT: More high quality RCTs with transparent parameters should be investigated to elucidate potential effects of MCT in the field of physical medicine and rehabilitation. At the present time MCT is an treatment option that could be helpful in particular for patients who are afraid of unpleasant sensations from electrotherapy with stronger currents.