Transcutaneous electrical nerve stimulation as an adjunct to education and exercise for knee osteoarthritis

The authors conducted this study to find the additional effects of Transcutaneous Electrical Nerve Stimulation (TENS) for knee osteoarthritis (OA) when administered in addition to a group education and exercise programme (‘knee group’).  The study was a randomised sham-controlled clinical trial. Patients referred for physiotherapy with suspected knee OA (confirmed using the American College of Rheumatology clinical criteria) were invited. Exclusion criteria included co-morbidities preventing exercise, previous TENS experience and TENS contraindications. Prospective sample size calculations required n=67 in each trial arm. 224 participants (mean age 61 years, 37% men) were randomised to three arms: TENS & knee group (n=73); Sham TENS & knee group (n=74); knee group (n=77). All patients entered an evidence-based six-week group education and exercise programme (‘knee group’). Active TENS produced a “strong but comfortable” paraesthesia within the painful area and was used as much as needed during the six-week period. Sham TENS used dummy devices with no electrical output. Blinded assessment took place at baseline, 3, 6, 12 and 24 weeks. The primary outcome was the Western Ontario & McMaster Universities Osteoarthritis Index (WOMAC) function subscale at 6 weeks. Secondary outcomes included WOMAC pain, stiffness and total scores; extensor muscle torque; global assessment of change; exercise adherence; and exercise self-efficacy. Data analysis was by intention to treat. The outcomes of all the patients in their study improved over time (p<0.05) but there were no differences between trial arms (p>0.05). All improvements were maintained at 24-week follow-up.

The authors concluded that there were not any added benefits of TENS, failing to support its use as a treatment adjunct under these circumstances.