Quantification of elastic properties of Achille's tendon: a first step to explore muscle-tendon structures exposed to substantial injury incidence

Tendons are actors in the transmission of forces deployed by muscles and thus are of capital importance for the high-performance of athletes. However, athletes are often prone to injuries such as tendinopathy. In this work we investigate supersonic shear imaging techniques to characterize mechanical properties of Achilles tendon. The aim of our study is to confirm the utility of stiffness measurement to monitor tendon and to develop new biomarkers such as shear wave attenuation to improvethis monitoring. The question that this study attempts to answer concerns the reproducibility over time of the measurement of the mechanical properties of tendon tissue and its impact on the conclusions of the health status of athletes. The volunteers' feet are positioned at an angle of 20°. In this configuration, the shear modulus is equal to
$227 \pm 121$
kPa and the attenuation
$40 \pm 14$
Np/cm/Hz. The inter-day coefficient of variation is calculated to quantify the minimum measurable variation that would result from tendon tissue pathology, 21.4% for the shear modulus and 12.5% for the attenuation.