Development and validation of a musculoskeletal model of the pelvis in response to lateral impacts

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My general field of interest is musculoskeletal biomechanics related to tissue loading, and the role that advanced age has on these relationships. Within this framework, the proposed program of research will generate novel insights into the basic mechanisms underlying dynamics of the pelvis during lateral impacts. For the 5-year horizon of the proposed grant, my short-term objectives are to characterize system state parameters of the body at the moment of impact initiation during lateral falls on the hip (Theme 1). This knowledge will inform the medium-term objectives of developing and validating a robust mathematical model that accurately predicts the loads applied to the pelvis during fall-related impacts. The initial stages of model development will focus on low-energy impacts from human volunteers (Theme 2). Specifically, 200 human participants will undergo low-energy sideways falls on the hip in a variety of body configurations. Data collected will include applied forces, pressure distribution, kinematics, and muscle activation levels. In addition, detailed skeletal geometry and body composition assessments will be conducted using dual x-ray absorptiometry, ultrasound, and body impedance analysis. The resulting data will be used to develop a mathematical model that accurately predicts the time-varying loads applied to the lateral pelvis during sideways falls on the hip. A variety of model types will be evaluated including: i) lumped-parameter; ii) Hertzian contact; and iii) multiple regression approaches. The most promising model will undergo initial validation using a subset of participant data. In Theme 3, cadavers (accessed through the University of Waterloo's School of Anatomy) will be used to further validate, or refine, the pelvic model of impact. In addition to replicating the low severity impacts performed by human volunteers, model validation will be extended to higher energy impacts more representative of worst-case fall scenarios. Theme 4 of the research will employ similar approaches, but will utilize mechanical hip impact simulators (i.e. a drop tower) to generate the experimental data used for subsequent model validation/refinement. The final phase of the proposed research (Theme 5) will utilize all experimental paradigms to investigate the ability of novel engineering devices and materials to alter impact dynamics during lateral falls on the hip. In summary, the proposed research is novel in its use of complementary research paradigms that will collectively result in a robust, and extremely well-validated, musculoskeletal model of the pelvis in response to lateral impacts. In addition, the resulting data will provide fundamental insights into the biomechanical properties of engineering-based protective devices and materials which could be integrated into the design of more effective products in future research applications.