GTN AND ACHILLES TENDINOPATHY – DOES IT WORK AND IF SO, HOW?

Abstract

Introduction: A recent clinical study has suggested that topical GTN may improve the outcome of non-insertional Achilles tendinopathy. The mechanism for this improvement is obscure but is thought to be due to modulation of local nitric oxide (NO) levels. The purpose of this study was to assess the clinical and histological results of topical GTN for non-insertional Achilles tendonitis.

Methods: 40 patients with non-insertional Achilles tendonitis underwent standard non-operative therapy. 20 patients also used topical GTN daily. AOFAS, AOS visual analogue scores and SF36 forms were completed pre-treatment and 3 months later.

Patients who failed conservative treatment and underwent surgery had histological examination of achilles tendon and histochemical analysis for isomers of NOS (eNOS and iNOS) as a marker of NO production.

Results: There was an overall improvement in symptoms in both groups but no significant difference in the improvement bewtween them – there was no additional benefit in using GTN patches. 4 patients also had to stop using patches within 3 weeks because of headaches.

Histological examination did not show any difference in collagen synthesis or remodelling between the 2 groups and there was no evidence of stimulated wound fibroblasts in the GTN group. There was no difference between the groups in the expression of eNOS or iNOS.

Conclusion: This study fails to demonstrate any improvement in symptoms when using GTN patches. There is no histological evidence that GTN promotes degenerate tendon to stimulate wound fibroblasts and increase collagen synthesis and remodelling. GTN patches do not appear to modulate the expression of NOS enzymes in diseased Achilles tendon. The use of GTN patches in the treatment of non-insertional Achilles tendonitis remains questionable and the role of NO as a mediator of inflammatory response remains elusive.