Deformation of collagen-based tissues investigated using a systematic review and meta-analysis of synchrotron x-ray scattering studies

Collagen fibrils are the building blocks of many tissues from fish scales and tendons to bone. Synchrotron small-angle X-ray scattering (SAXS) with in situ mechanical testing is a powerful tool to investigate collagen fibril deformation. There is a need to combine data from SAXS studies to investigate structure-function relationships. A literature search used the concepts of mechanical properties, collagen, and SAXS, with 52 articles meeting the eligibility criteria. Here, we report that mineralized tissues transfer a greater proportion of tissue-scale deformation to the fibril: 67% for cortical bone, 49% for tendon, 10% for ligament, and 3% for skin. Across non-mineralized tissues, tissues with less complexity and greater elastin content transfer less deformation to the fibril. The meta-analysis finds 20%–40% lower fibril strain in human aging and disease compared to controls, which contributes toward fracture risk. This synthesis demonstrates how variations in composition and structure tune material properties in collagen-based tissues.