Effect of Rehabilitation Exercise on Achilles tendinopathy- a Rat Model

Abstract

The Achilles tendon plays an important role in plantar flexion of ankle joint The Achilles tendinopathy often occurs in athletes and it associates with tenderness pain and the long duration of conservative treatments Strengthening and stretching exercises are commonly adapted to improve the pain score or activity level in clinical rehabilitation The purpose of this study is to investigate the effects of different rehabilitation protocols on mechanical properties and sonographic assessments of the Achilles tendon with a rat model The tendinopathy rat model was established by injecting collagenase in the Achilles tendon After resting for 4 weeks 12-week-old male Sprague-Dawley rats with a medium severity level of sonographic assessments were randomly assigned to 4 groups eccentric group concentric group passive range of motion group and control group A self-designed rehabilitation system was developed and used to control the angular velocity the range of motion of ankle joint and contraction types as well as generate calf muscles contraction using electrical stimulation After 6 weeks of training the sonographic assessments were tested Then the specimen including parts of gastrocnemius Achilles tendon and calcaneus was collected for the following tensile testing By Mann-Whitney analysis there are significant differences between EE and CE groups in their maximum force (p=0 032) and maximum stress (p=0 032) However neither maximum stress nor maximum force has correlation with integral torque The results might explain why isolated eccentric exercise has better clinical effects on healing Achilles tendinopathy than isolated concentric exercise The higher torque exerted from eccentric than concentric contraction may not be the dominant impact on why eccentric exercise is more effective than concentric exercise for healing Achilles tendon In addition correlating the results of mechanical testing with sonographic assessments there are moderately negative correlation between Young’s modulus and echogenicity (r=-0 483) as well as moderate correlation between cross-sectional area and vascularity (p=0 469) These results provide the links from the non-invasive sonographic assessments to the mechanical properties of the tendon

Date of Award	2014 Aug 29
Original language	English
Supervisor	Fong-chin Su (Supervisor)