Comparison of the efficacy of transcutaneous electrical nerve stimulation, interferential currents, and shortwave diathermy in knee osteoarthritis: a double-blind, randomized, controlled, multicenter study.

OBJECTIVE: To compare the effectiveness of transcutaneous electrical nerve stimulation (TENS), interferential currents (IFCs), and shortwave diathermy (SWD) against each other and sham intervention with exercise training and education as a multimodal package.

DESIGN: A double-blind, randomized, controlled, multicenter trial.

SETTING: Departments of physical medicine and rehabilitation in 4 centers.

PARTICIPANTS: Patients (N=203) with knee osteoarthritis (OA).

INTERVENTIONS: The patients were randomized by the principal center into the following 6 treatment groups: TENS sham, TENS, IFCs sham, IFCs, SWD sham, and SWD. All interventions were applied 5 times a week for 3 weeks. In addition, exercises and an education program were given. The exercises were carried out as part of a home-based training program after 3 weeks' supervised group exercise.

MAIN OUTCOME MEASURES: Primary outcome was a visual analog scale (0-100mm) to assess knee pain. Other outcome measures were time to walk a distance of 15m, range of motion, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Nottingham Health Profile, and paracetamol intake (in grams).

RESULTS: We found a significant decrease in all assessment parameters (P<.05), without a significant difference among the groups except WOMAC stiffness score and range of motion. However, the intake of paracetamol was significantly lower in each treatment group when compared with the sham groups at 3 months (P<.05). Also, the patients in the IFCs group used a lower amount of paracetamol at 6 months (P<.05) in comparison with the IFCs sham group.

CONCLUSIONS: Although all groups showed significant improvements, we can suggest that the use of physical therapy agents in knee OA provided additional benefits in improving pain because paracetamol intake was significantly higher in the patients who were treated with 3 sham interventions in addition to exercise and education.