0761 - Heterogeneity of Mechanical Properties of Bone Collagen

Introduction: It has been suggested that collagen provides the ductility in bone [1], but the relationship between the failure properties of intact bone and isolated bone collagen has not been investigated. Such a relationship could have substantial clinical implications since ductility, which decreases with age [2-4], affects the ability of bone to deform rather than fracture under severe loading situations such as a fall. Part of the difficulty in establishing such a relationship is the wide range of mechanical properties reported for isolated bone collagen [1, 5-9]. The only explanation for these discrepancies so far has been differences in mechanical testing techniques. Since each previous study examined bone from only one species and anatomical site, it is possible that these differences are due to species and site-related heterogeneity in weight fraction or microstructure of the collagen. Additionally, the mechanical properties of bovine and human bone collagen have never been compared, so the use of a bovine model to investigate age and disease-related affects in humans has not been substantiated. The specific aims of this study were to: 1) compare the mechanical properties of bone collagen from different species and anatomical sites in order to determine if differences reported previously are due to testing technique or tissue heterogeneity and, 2) assess the validity of a bovine model for studying the properties of human bone collagen.