Topical glyceryl trinitrate (GTN) and eccentric exercises in the treatment of mid-portion achilles tendinopathy (the NEAT trial): a randomised double-blind placebo-controlled trial.

Achilles tendinopathy affecting the middle portion of the tendon is a stubborn, often long-lasting problem, and eccentric exercise (a specific way of loading the calf muscle) is the standard treatment even though many people still struggle with symptoms. This trial asked whether adding daily glyceryl trinitrate (GTN) ointment, a nitric-oxide releasing treatment previously suggested to help tendon healing, on top of a structured eccentric exercise programme, would improve outcomes more than adding a placebo ointment to the same exercise programme. Both groups improved over the 24 weeks on the main measure of pain, function and activity, but the improvement with GTN was not significantly different from placebo at any of the follow-up points, and none of the secondary measures, including pain, calf strength or ultrasound findings, differed between groups either. This is interesting because it challenges the idea that GTN adds meaningful benefit beyond exercise alone.

The main limitation is that this was a single-site trial with a modest number of participants, so it cannot rule out smaller effects that a larger study might detect.

If you've had ongoing pain in the middle part of your Achilles tendon, you'll know that exercise programmes involving slow, controlled calf loading are usually recommended as first-line treatment. This study looked at whether adding a nitroglycerin-based ointment, applied daily to the skin over the tendon, would help people recover faster or more fully than exercise alone. Everyone in the trial did the same 12-week exercise programme, and half also used the active ointment for 24 weeks while the other half used a placebo ointment that looked and felt the same.

Both groups improved over time, which is encouraging on its own, but the group using the active ointment did not do better than the placebo group on pain, function, activity levels, calf strength, or tendon appearance on ultrasound. This suggests that adding this particular ointment to an exercise programme does not offer extra benefit, at least based on this trial. It was a single, moderately sized study, so it does not close the door completely, but it does not support routine use of the ointment either.

This is a summary of research, not medical advice. Talk to your own healthcare provider about anything affecting your care.

This randomised, double-blind, placebo-controlled trial (n=76) compared 24 weeks of daily topical GTN ointment plus a 12-week eccentric loading programme against placebo ointment plus the same exercise programme, in patients with chronic mid-portion Achilles tendinopathy. The primary outcome, VISA-A score, improved significantly within both groups at 6, 12 and 24 weeks, but intention-to-treat analysis found no statistically significant between-group difference at any time point (adjusted mean differences: -1.33 at week 6, 95% CI -6.96 to 4.31; -1.25 at week 12, 95% CI -8.0 to 5.49; -3.8 at week 24, 95% CI -10.6 to 3.0, negative values favouring GTN). Secondary outcomes, including pain severity, self-reported function, calf muscle function, pressure pain thresholds and ultrasound tendon changes, also showed no significant between-group differences across follow-up.

The within-group improvements in both arms are consistent with the known effect of eccentric exercise itself, and cannot be attributed to either ointment. As a single-site trial with a moderate sample size, this study cannot exclude smaller clinically relevant effects, and confidence intervals were wide enough to be compatible with both modest benefit and modest harm from GTN. These findings do not support adding GTN to eccentric exercise for this population.