Introduction From previous research on tendinopathy of the Achilles tendon, wrist extensors and the supraspinatus, it is known that topical glyceryl trinitrate (GTN) has a healing effect. To our knowledge, no studies have been published on the application of GTN in patients with PT.
The aim of this study was to assess if continuous topical GTN treatment improved outcome in patients with chronic PT compared to placebo patches, both combined with heavy load eccentric training.
Methods A randomised double blind, placebo-controlled clinical trial was done, comparing a 12 week programme of using a GTN patch or placebo patch in combination with eccentric squats on a decline board. Measurements were performed at baseline, 6, 12 and 24 weeks. Primary outcome measure was the VISA-P questionnaire. Secondary outcome measures were patient satisfaction and pain scores during sports. Generalised Estimated Equation was used to analyse the treatment, time and treatment x time effect. Analyses were performed following the intention-to-treat principle.
Results VISA-P scores for both groups improved over the study period to 75.0±16.2 and 80.7±22.1 at 24 weeks. Results showed a significant effect for time (p<0.01) but no effect for treatment x time (p=0.80). Mean VAS pain scores during sports for both groups increased over the study period to 6.6±3.0 and 7.8±3.1. Results showed a significant effect for time (p<0.01) but no effect for treatment x time (p=0.38). Patient satisfaction showed no difference between the GTN and the placebo group (p=0.25) after 24 weeks, but did show a significant difference over time (p=0.01). Three patients in the GTN group reported some rash.
Discussion Continuous topical GTN treatment in addition to an eccentric exercise programme does not improve clinical outcome compared to placebo patches and an eccentric exercise programme in patients with chronic patellar tendinopathy.