Adaptation of Tendon Structure and Function in Tendinopathy With Exercise and Its Relationship to Clinical Outcome.

CONTEXT: Exercise is seen as the most evidence based treatment for managing tendinopathy and although the type of exercise used to manage tendinopathy may induce adaptation in healthy tendons, it is not clear whether these adaptations occur in tendinopathy and if so whether they are associated with improved clinical outcomes.

OBJECTIVE: The aim of the study was to synthesise available evidence for adaptation of the Achilles tendon to eccentric exercise and the relationship between adaptation (change in tendon thickness) and clinical outcomes among people with Achilles tendinopathy.

EVIDENCE ACQUISITION: The search was performed in September 2018 in several databases. Studies investigating the response (clinical outcome, imaging on US/MRI) of pathological tendons (tendinopathy, tendinosis, partial rupture) to at least 12 weeks of eccentric exercise were included. Multiple studies that investigated the same interventions and outcome were pooled and presented in effect size estimates, mean difference (MD) and 95% confidence intervals if measurement scale were the same, or standard mean difference (SMD) and 95% confidence intervals if measurements scales were different. Where data could not be pooled the studies were qualitatively synthesised based on van Tulder et al.

EVIDENCE SYNTHESIS: Eight studies met the inclusion and exclusion criteria and were included in the review. There was strong evidence that Achilles tendon thickness do not decrease in parallel to improved clinical outcomes.

CONCLUSIONS: Whether a longer time to follow up is more important than the intervention (i.e. just the time per se) for a change in tendon thickness as is still unknown? Future studies should investigate whether exercise (or other treatments) can be tailored to optimize tendon adaptation and function, and whether this relates to clinical outcomes.