Computer Simulation of Impact Response of the Human Knee Joint in Car-Pedestrian Accidents

Abstract

Analysis of results from previous mathematical simulations of pedestrian impacts shows that a standard description of the pedestrian model used in the MADYMO is not comparable with simulations performed with biological materials. A 3D pedestrian knee joint model was developed to achieve a better correlation with the results from previous cadaver experiments. The model of the knee joint includes the articular surfaces, ligaments and capsule represented by the ellipsoid and plane elements as well as the spring-damping elements, respectively. The mechanical properties of the knee joint are based on available biomechanical data. To verify the pedestrian model with previous cadaver experiments, the computer simulation have been carried out with our new model of the knee joint by the MADYMO 3D program. To simulate different test conditions which correspond to previous cadaver tests, the following parameters have been varied in our simulations: impact speed, bumper height and bumper compliance. Four computer simulations were performed which were compared with four cadaver test series with five experiments in each series. The bumper force, the condyle interface forces, the ligament forces and the ligament relative elongations were calculated and compared with the results of the cadaver experiments. The output parameters calculated from the new knee joint model correspond well to what was observed in cadaver studies. Two complementary computer simulations were performed to study influence of the upper body to distribution of the forces in the simulated knee structures. From this simulation it seems that body mass has influence on the condyle forces and the trajectory of the lower extremities.