Anterior Tibia Impacts: A Biofidelity Study between Post-Mortem Human Subjects and Anthropomorphic Test Devices

Injuries to the posterior cruciate ligament (PCL) commonly result from frontal automobile crashes when the occupant’s tibia interacts with the intruding knee bolster of the vehicle. The goal of this research study was to better understand injury to the PCL due to this impact scenario and correlate injury with the response of the knee slider of today’s crash test dummies. Over a span of two years, fourteen post-mortem human subject (PMHS) lower extremities were impacted on the anterior aspect of the tibia, just distal to the tibial tuberosity. The impactor was a 24 kg pneumatic ram with a padded face to simulate the stiffness of a knee bolster. The PMHS tests revealed the stiffness of the knee to be a viscoelastic response and the tibia could displace almost 23mm in relation to the femur before the occupant had a 50% chance of tearing their PCL. Following the PMHS testing, five anthropomorphic test device (ATD) lower extremities were subjected to similar impact conditions. The tested ATDs included the 5 th female, 50 th male standard HIII legs with the ball bearing slider and linear slider, the 5 th female FLX and 50 th male LX lower extremities. The testing revealed that all of the ATD legs were repeatable and the knees had similar stiffnesses no matter what impact energy level was used. The displacement between the tibia and the femur in the ATDs never reached more than 15 mm.