Abnormal deformation and failure of bone tissue at the smallest level directly contributes to the incidence of bone fragility fractures in the elderly. These fractures are a major concern for the health care of elderly and osteoporotic patients because the fractures often cause death and are always painful. Fragility fractures are mainly caused by negative changes in the shape of the whole bone and also by negative changes in the bone tissue itself that are caused by age, disease or as drug side-effects. There is no validated model for how the bone ultrastructure creates the properties of the whole bone. As a result, it isn't currently possible to understand which of the changes in the tissue directly cause a weakening of the whole bone. This research will create fundamental understanding of the ultrastructural origins of such bone fragility fractures. The results will bridge the knowledge gap between the nano-structure biology and whole bone biomechanics of bone, thus enabling future advances in effective prediction and prevention of bone fragility fractures. The multidisciplinary approach will help broaden participation of underrepresented students in research and bring in positive impacts on engineering education.
The unique multiscale modeling approach in this study will, for the first time, allow for a systematic investigation on the ultrastructural origins of bone fragility fractures. Briefly, bone will be computer modeled as a composite of mineralized collagen fibrils embedded in an extrafibrillar matrix based on the extensive experimental and analytical observations provided in the literature and collected by the investigators in previous research. A cohesive finite element approach will be used to capture the ultrastructural behavior of bone tissue and its relationship with the bulk properties of a whole bone. Based on simulations, the relationships between ultrastructural features and the in situ and bulk mechanical behavior of bone will be established. The efficacy of the multiscale model in prediction of bulk bone behavior based on ultrastructural features will be tested for accuracy using several in vitro and in vivo experiments.
