The goal of this study was to develop a mathematical model of the lower extremity capable of predicting injury risk and simulating the kinetic and kinematic response of the pedestrian lower extremity under vehicle impact loading. The hip-to-foot multi-body model incorporates a detailed facet contact surface, 50th percentile male anthropometric and inertial properties, and stiffness and failure tolerances from the most recent literature. Model validation was achieved using a combination of parameter optimization for component-level kinetic response and full-scale simulations for kinematic response. The three-dimensional kinematic response of the struck-side lower extremity of seven post-mortem human surrogates struck laterally by a sedan at 40 km/h is also presented.