Design: Randomised, sham-controlled superiority trial with blinded outcome assessment
Population: 96 adults with knee osteoarthritis in an exercise therapy programme
Primary outcome: KOOS pain subscale
Effect: Adjusted difference 1.05 points (95% CI −5.19 to 7.29) post-intervention

A Brazilian sham-controlled trial randomised 96 people with knee osteoarthritis to a structured exercise programme with either active high-frequency TENS or sham stimulation during sessions. The idea was that pain relief during movement might help people exercise more effectively.

There was no difference in knee pain on the KOOS pain subscale after the programme or at one month, and the confidence intervals excluded the pre-set 10-point minimal important difference. None of the secondary outcomes — function, strength, self-efficacy, disability — differed either. No adverse effects were reported.

The trial lacked an exercise-only arm, did not formally test whether blinding held, and followed patients only for a month. Within those limits, it does not support adding TENS during exercise sessions. Exercise itself remains the core treatment.

Prioritise a structured exercise programme as first-line treatment for knee osteoarthritis.
Do not add high-frequency TENS during exercise sessions expecting extra pain relief; this trial found none.
Redirect time and cost towards supervised exercise, weight management and education.
Address movement-evoked pain with pacing and graded progression rather than adjuncts.

Why it matters

TENS is widely used in physiotherapy clinics, and this trial suggests it may not add to what exercise already achieves.

The statistics, in plain English

The mean difference in pain was about 1 point on a 100-point scale (95% CI −5.2 to 7.3). Even the upper end of that interval is below the 10 points patients would notice, so a meaningful benefit is unlikely.