To clarify the mechanism of hip fracture and investigate the method of fracture prevention, we developed a fall simulation system which considers the boundary conditions at real fall accidents using a multibody-finite element hybrid model. The hybrid model consists of a detailed finite element model of thigh and hip joint, and multibody model of the other parts of a whole human body. The simulation results showed that knee grounding fall caused hip fracture risk higher than the risk by a lateral impact on the greater trochanter. By comparing the regions of stress concentration, we estimated that a knee grounding causes a cervical fracture while a trochanter grounding may cause a trochanteric fracture.
