This paper presents a finite element model of the human lower extremity skeleton system to facilitate the investigation of dynamic responses of the lower extremity to lateral impact loading. The model consists of the femur, the tibia, and the knee ligaments. The geometry and mass distribution of the model were chosen to represent a 50th percentile male lower extremity skeletal structure based on anatomical measurements and available data. The model was constructed using solid hexahedron elements, shell elements and nonlinear spring-damper elements. Linear viscoelastic material was used to describe the mechanical property of the long bones. Boundary conditions were defined in accordance with the configuration of a car-pedestrian lateral collision.

The model was implemented by means of the finite element program DYNA3D. The tibia segment of the model was validated against the published three-point bending test with human leg specimens. The whole model was validated against previously performed tests with lower extremity specimens at impact speeds of 30 and 17 km/h. A stress analysis was performed in terms of the injury mechanism of the lower extremity to a lateral impact loading. The calculated peak tensile stress in the model at impact speed 30 km/h is 160 MPa which corresponds to the stress level of failure of the tibia. At impact speed 17 km/h the peak tensile stress is 102 MPa that is lower than the ultimate tensile stress of the tibia.

The model facilitates the calculation of detailed physical quantities such as stress distribution within simulated structures, and contributes to a better understanding of injury mechanisms at the level of stress analysis.