This Faculty Early Career Development (CAREER) grant will improve our understanding of the mechanistic origins of fatigue fracture in aged and diabetic fragile bones. This will be achieved by combining low-radiation images of bone damage with mechanical testing of bones and machine learning. This is important because fatigue (cyclic) fracture is a prevalent failure mechanism in nearly all engineered structures, but its relevance to the field of bone tissues has been neglected. These fatigue fractures are common in young athletes, especially in dancers. These fractures are also common in those who have bone fragility. For example, aged and diabetic bones have poor collagen quality and become fragile. Fractures are often thought to be the result of a single overload event, such as a fall. However, this may not explain the cause of all catastrophic fractures because it overlooks the role of fatigue from daily activities. This research project will develop novel dynamic imaging and machine learning for capturing the origins of bone failure mechanisms and associated risk factors. The results will ultimately be used to prevent fragility fractures. This research will provide a transferrable methodological framework for medical imaging, and foster the development of new fracture-resistant materials inspired by biological design principles. The research will be integrated into a long-term educational plan to attract the next generation of female engineers through dance class and other creative learning supports. It is of note that female engineering students in Utah, where this work will be done, are particularly underrepresented in comparison to the rest of the United States.
The specific goal of the research is to advance the development of new bone fracture mechanics theory by using a novel synthesis of synchrotron radiation micro-computed tomography and specific machine learning algorithms to capture the 3D damage evolution during mechanical loading. Previous work has shown that this is typically not achievable by standard synchrotron micro-computed tomography imaging, which involves high radiation doses and causes deterioration of tissueâ€™s mechanical properties. The research work will test the hypothesis that collagen cross-linking accumulation and other diabetic changes in bone quality play an important role in driving fragility fractures. The research tasks of this project include: (i) determine the (sole) effect of collagen cross-linking accumulation on fatigue and fracture resistance ; (ii) evaluate the contribution of collagen cross-linking accumulation in diabetic bone resistance compared with other bone quality factors; (iii) quantify the microscale failure mechanisms in deforming diabetic and crosslinking-rich bones during in situ fatigue and fracture tests; and (iv) evaluate whether cyclic loadings might drive a significant fraction of fractures in diabetic and crosslinking-rich bones. This project can reveal the origins of damage mechanisms in all types of collagenous tissues, and has the potential to lower the radiation level and improve image quality of medical scans. This new knowledge will establish the PIâ€™s long-term career in bone fracture mechanics.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.