Mechano-adaptive models of healing tendons

Mechanical loading has been shown to positively influence tendon healing; however, the mechanisms remain unclear. This study aimed to evaluate the ability of biophysical stimuli - principal and deviatoric strain - in regulating healing using finite element (FE) method. Axisymmetric FE models were created based on a fibre-reinforced continuum formulation with distributed collagen fibre orientations, and the parameters were quantified using model fitting against experimental data of rat Achilles tendons during healing. A mechanoregulatory scheme proposed tissue types with higher stiffness could only form at lower strain. The mechano-adaptive simulations were performed in ABAQUS for strain analyses and in MATLAB to update material properties. A stimulus was counted to favour healing when fibre re-reorganisation progressed to completion following the expected sequence of tissue type turnover. Simulation result suggested that the mechano-adaptation when regulated by principal strain predicted re-organisation comparable to experimental findings.