Structure-function relationships in functionally distinct tendons: implications for multi-scale biomechanics

Tendon is a multi-scale fibre composite material, in which highly aligned collagen units are interspersed with a more hydrated proteoglycan-rich matrix at multiple nano-to macro-length scales, leading to a tissue with excellent uniaxial tensile strength and stiffness. However, despite this well-accepted universal hierarchical organisation, evaluation of the functional role of different tendons highlights that they vary considerably and require markedly varied mechanical characteristics. Specifically, energy storing tendons such as the Achilles must be highly extensible and able to store and release energy in an elastic manner. By contrast, positional tendons such as the digital extensor tendons of the hand require some dampening and the capacity to modulate muscle contraction into precise skeletal movement. These disparate functional requirements necessitate structural and compositional optimization, and our research has focused on characterising mechanistic structure-function differences between tendons and their impact on tendon biomechanics in health, disease and aging.