High-Risk Tissue Distribution in the Human Proximal Femur Under Sideways Fall Loading

Despite the central role of femoral strength in the etiology of osteoporotic hip fractures [1], the associated micromechanical basis of femoral strength remains poorly understood. Cadaver studies [2] using biomechanical testing have established that both the cortical and trabecular bone contribute to the structural integrity of the proximal femur but these studies did not address mechanisms. Addressing mechanisms, theoretical and finite element continuum analyses have assessed cortical-trabecular load sharing and have described stress and strain distributions throughout the proximal femur [1,3]. However, the regions of the bone at highest risk of initial failure remain unclear, in part because the continuum nature and low spatial resolution of these previous analyses render them incapbable of capturing load transfer associated with the microstructure of the trabecular bone and the sometimes thin cortex. Overcoming this limitation, micro-CT-based finite element analysis has recently been applied to the entire proximal femur [4], but so far only two femurs have been analyzed and thus reported trends are difficult to generalize. To extend this recent work and provide further insight into the microstructural basis of femoral strength, we applied micro-CT based finite element analysis to investigate femoral micro-mechanics in a cohort of elderly human proximal femurs.