Effects of capacitive and resistive electric transfer therapy in patients with knee osteoarthritis: a randomized controlled trial

Capacitive and resistive electric transfer (CRET), an endogenous diathermy treatment, has been demonstrated to reduce pain and improve quality of life in numerous orthopedic degenerative and inflammatory problems but not in knee osteoarthritis (KOA). The aim of this prospective randomized controlled trial was to evaluate whether a 2-week program of CRET can reduce pain, stiffness and functional limitations in KOA compared with a sham treatment. Patients with KOA were randomly assigned to a study group (n = 31) or a control one (n = 22). The study group underwent six intermittent CRET applications, whereas the controls underwent a sham protocol without application of energy. The outcome measures were the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) (primary outcome) and the visual analogue scale (VAS) for pain and Medical Research Council Scale (secondary outcomes). All patients were evaluated before treatment (T0), at the end of treatment (T1), and at 1 (T2) and 3 months after treatment (T3). Results showed that CRET significantly improved strength, physical function and pain in patients with KOA. In the study group a reduction in WOMAC and VAS scores was observed at T1, T2, and T3 compared with T0. No significant changes of WOMAC and VAS scores were observed in the control group across all time points. Considering the small number of sessions, low cost and long-term benefits, CRET might be a useful therapeutic option for the conservative management of KOA to reduce pain, stiffness and functional limitation.