Multiscale Modeling of Ligaments and Tendons

Ligaments and tendons are composed primarily of water and fibrillar type I collagen, which is hierarchically organized into complex structures that span multiple physical scales. Forces at the macroscopic joint level are transmitted via interactions at the mesoscale, microscale and nanoscale. Tissue repair and growth is mediated by fibroblasts and tenocytes, which are subjected to a unique microscale mechanical environment. The burgeoning field of multiscale modeling holds promise in filling the gaps in our understanding of structure–function relationships and mechanotransduction in these tissues, and these questions are difficult or impossible to address using experimental techniques alone. This article reviews the state of the art in multiscale modeling of ligaments and tendons, while providing sufficient background on the structure and function of these tissues to allow a reader who is new to the area to proceed without substantial outside reading. The multiscale structure of ligaments and tendons is described in detail. The available data on material characterization at different physical scales is reviewed as well. The final section of the chapter summarizes the efforts at developing and validating multiscale models that are relevant to ligament and tendon mechanics, and identifies future directions for research. Multiscale modeling of tendon and ligament holds considerable promise in advancing our understanding regarding the complex mechanisms of multiscale force transfer within these tissues.