Three-year followup study of topical glyceryl trinitrate treatment of chronic noninsertional Achilles tendinopathy.

BACKGROUND

Topical glyceryl trinitrate treatment has demonstrated short-term efficacy in chronic noninsertional Achilles tendinopathy. No long-term followup is reported. We aimed to assess if the demonstrated efficacy of this treatment persisted 3 years after discontinuation of therapy.

METHODS

A follow-up study of 52 patients (68 tendons) treated with 6 months of glyceryl trinitrate therapy or placebo was performed 3 years after cessation of therapy. Assessment included pain scores, return to previous activity, the Victorian Institute of Sport Achilles tendon scale (VISA-A), asymptomatic patient outcomes, clinical assessment of tendon tenderness, and functional hop test.

RESULTS

Patients treated with topical glyceryl trinitrate had significantly less Achilles tendon tenderness (p = 0.03), and improved VISA-A scores (p = 0.04) than those in the placebo group; 88% (28 of 32 tendons) of patients were completely asymptomatic at 3 years (VISA-A score of 100) compared to 67% (24 of 36 tendons) of patients treated with rehabilitation alone (p = 0.03 with Chi square analysis). Other outcome measures showed nonsignificant trends towards improvement in the glyceryl trinitrate group (pain scores p = 0.07, functional hop test p = 0.07, and return to sport p = 0.16). The mean estimated effect size for all outcome measures was 0.21.

CONCLUSIONS

Topical glyceryl trinitrate treatment has demonstrated efficacy in treating chronic noninsertional Achilles tendinopathy, and the treatment benefits continue at 3 years. Significant differences in asymptomatic patient outcomes for the glyceryl trinitrate group continue at 3 years, and this is confirmed by the effect size estimate. This suggests that the mechanism of action of topical glyceryl trinitrate on chronic tendinopathies is more than an analgesic effect.