Add on GTN ointment to exercise programme fails to improve pain and function in chronic mid-portion Achilles tendinopathy: study

Kirwan PD et al conducted a study to investigate if daily treatment with glyceryl trinitrate (GTN) ointment, over 24 weeks combined with a 12-week eccentric exercise programme is more effective for chronic mid-portion Achilles tendinopathy than placebo ointment and eccentric exercise.

GTN is a drug which delivers nitric oxide (NO). Inhibition of NO has been shown to impair tendon healing, whereas the addition of NO has been shown to enhance tendon healing. Only two studies have specifically assessed the use of GTN to deliver NO in Achilles tendinopathy, yielding conflicting results.

This was a single-site randomised double-blind placebo-controlled trial at an acute hospital, Dublin, Ireland. Patients with chronic mid-portion Achilles tendinopathy were randomised to either 24 weeks of daily GTN ointment or placebo ointment. Both groups received an identical 12-week eccentric exercise programme. The primary outcome measure was the Victorian Institute of Sport Assessment–Achilles (VISA-A) questionnaire at 24 weeks, which measures pain, function and activity. Secondary outcomes included pain severity, self-reported physical function, calf muscle function, pressure pain thresholds and ultrasound changes. Statistical analyses were performed according to intention-to-treat principles.

Key findings of the study were:

• 76 patients (30 women; 46 men, mean age ± SD, 45.6 ± 8.2 years) were recruited for the trial.

• Significant improvements in VISA-A scores occurred in both groups at 6-week, 12-week and 24-weekfollow-up.

• The increase was not significantly different between groups, adjusted mean between-group difference from baseline to week 6, –1.33 (95% CI –6.96 to 4.31); week 12, −1.25 (95% CI −8.0 to 5.49) and week 24, –3.8 (95% CI –10.6 to 3.0); negative values favour GTN.

• There was no significant between-group difference in any of the secondary outcome measures at 6, 12 and 24 weeks.

The authors concluded that – “adding daily GTN ointment over 24 weeks to a 12-week eccentric exercise programme did not improve pain, function and activity level in patients with chronic mid-portion Achilles tendinopathy when compared with placebo ointment.” 

Further reading:

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 Kirwan PD et al. Br J Sports Med 2024;58:1035–1043. doi:10.1136/bjsports-2023-108043