Virtual Reconstruction of Long Bone Fracture in Car-to-pedestrian Collisions Using Multi-body System and Finite Element Method

Abstract

Lower limb injures are frequently observed in passenger car traffic accidents. Previous studies of the injuries focus on long bone fractures by using either cadaver component tests or simulations of the long bone kinematics, which lack in-depth study on the fractures in stress analysis. This paper aims to investigate lower limb impact biomechanics in real-world car to pedestrian accidents and to predict fractures of long bones in term of stress parameter for femur, tibia, and fibula. For the above purposes, a 3D finite element (FE) model of human body lower limb (HBM-LL) is developed based on human anatomy. The model consists of the pelvis, femur, tibia, fibula, patella, foot bones, primary tendons, knee joint capsule, meniscus, and ligaments. The FE model is validated by comparing the results from a lateral impact between simulations and tests with cadaver lower limb specimens. Two real-world accidents are selected from an in-depth accident database with detailed information about the accident scene, car impact speed, damage to the car, and pedestrian injuries. Multi-body system (MBS) models are used to reconstruct the kinematics of the pedestrians in the two accidents and the impact conditions are calculated for initial impact velocity and orientations of the car and pedestrian during the collision. The FE model is used to perform injury reconstructions and predict the fractures by using physical parameters, such as von Mises stress of long bones. The calculated failure level of the long bones is correlated with the injury outcomes observed from the two accident cases. The reconstruction result shows that the HBM-LL FE model has acceptable biofidelity and can be applied to predict the risk of long bone fractures. This study provides an efficient methodology to investigate the long bone fracture suffered from vehicle traffic collisions.