Tangent modulus estimation of Achilles tendon from ultrasound images

Liliam F. Oliveira¹; Carolina Peixinho¹; Gabriel Abreu e Silva¹; Luciano L. Menegaldo¹

¹ UFRJ

doi:10.20906/CPS/COB-2015-1043

Resumo

The nonlinear nature of tendon elastic properties suggest that tangent modulus is a property that better describe its behavior than a fixed value of the modulus of elasticity. Here, Achilles tendon tangent modulus is estimated in vivo, calculating the integral of incremental strains along the tendon length change and the true area, estimated from tendon diameter measurements and Poisson's ratio. Passive mobilization was applied at the ankle of the volunteers, with a dynamometer at a slow velocity (5°/s). Tendon elongation was tracked with ultrasound images, by monitoring the displacement of the myotendinous junction. Maximum values for tangent modulus were greater than the modulus of elasticity calculated from engineering stress and strain. Such differences increase for larger deformations.

Palavras-chave: biomechanics; Achilles tendon; mechanical properties