Experimental and numerical investigations of factors influencing bone fracture tolerance

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This research is concerned with the development of comprehensive injury criteria and injury-predicting finite element (FE) models, with a focus on the lower leg. Injury criteria are used by a variety of industries (e.g., automotive, defence) to evaluate protective systems, but have historically been oversimplified. Furthermore, computer models are commonly used to evaluate fracture risk, but little work has been done to ensure that bone is properly modeled. Lower leg injuries are frequent in accidents and can have significant long-term effects on quality of life. As such, there is a need for improved injury criteria and enhanced numerical models to better understand these injuries and assess the potential of novel protective technologies. The effect of loading rate and lower leg posture are two significant factors that will influence injury risk, but have yet to be investigated. Through experimental testing of cadaveric specimens new injury criteria will be developed that include the effect of load duration, leg angle and ankle position. This will permit more appropriate evaluation of devices such as footrests and energy attenuating materials for their protective capabilities. Corresponding loads measured by 'crash test dummies' will be determined, thus providing guidelines to industry for safety assessments. As well, an instrumented boot will be developed to provide a means to evaluate injury risk to the foot/ankle, a region not yet instrumented. Studies will be conducted to determine the optimal parameters needed to model bone for injury predicting computer studies, and a numerical model of the lower leg will be developed and validated against the aforementioned test data. The factors which influence injury risk are not well understood. By further developing the injury criteria used to evaluate safety measures, the prevalence of debilitating traumatic injuries can be reduced. This will result in a better protected population and reduced long term effects for those involved in traumatic events.