AB0079 EFFECT OF HYALURONIC ACIDLOCAL INJECTIONS ON ACHILLES TENDINOPATHIES: AN OBSERVATIONAL STUDY ON TENDON VISCOELASTIC PROPERTIES AND THEIR RELATIONSHIPS WITH CLINICAL OUTCOMES

Abstract

Background: Effect of hyaluronic acid local injections on Achilles tendinopathies: an observational study on tendon viscoelastic properties and their relationships with clinical outcomes. Objectives: Achilles tendinopathy (AT) affects athletes, recreational exercisers and also inactive people, where it is sometimes associated with arthritic phenotypes. The aim of this study was to evaluate the efficacy of a three-local injections regimen of hyaluronic acid (HA) in middle aged patients with a diagnosis of AT; the relationships of the functional, biochemical and clinical outcomes with the viscoelastic properties of the tendon were also studied Methods: 8 patients previously diagnosed for monolateral AT were enrolled. AT was confirmed before the first local HA injection (T0) by clinical examination, MRI and thermography. At T0 patients were assessed for maximal voluntary isometric contraction (MVI) involving Achilles tendon (both injured and healthy), and pain level with a Likert scale; Achilles tendon viscoelastic state, i.e. tone and stiffness, were then measured at relaxed state and at 10% of MVI with MyotonPro (Myoton Ltd, UK). Finally patients received the first HA injection (RegenFlex T&M, a blend of 2 to 1000 KDa HA, Regenyal, IT). All the measurements were repeated at T1 (15 days after the first injections and immediately prior the second), at T2 (15 days after the second injection and prior the third) and at T3 (15 days after the third injection), i.e. over a total of 45 days in which clinical visits were also performed. Furthermore, before each injection, injured tendon exudates were collected by needle aspiration and the levels of IL-1β and matrix metalloprotease 3 (MMP-3) were determined with an ELISA test. Results: At T0, pain score and MVI were significantly higher and lower in injured tendons, respectively. Accordingly, tone and stiffness values were significantly different between injured and contralateral tendons, especially when measured at the relaxed state. Interestingly, the above differences gradually disappeared at T1, 2 and 3. In keeping with these results, tendon exudates volumes also decreased over time, as well as the levels of IL-1β and MMP-3. Conclusion: RegenFlex T&M promoted a progressive healing of AT, with recovery of clinical, functional and tendon’s viscoelastic state.