This study examined the biomechanical response of the lumbar spine, including kinematics and kinetics, of six post mortem human subjects (PMHS) during frontal motor vehicle impacts of 20 and 40 kph. Frontal motor vehicle impacts were simulated using the frontal impact sled system at the University of Virginia. Subjects were male and chosen such that their anthropometry approximated the 50 percentile male size and mass. The kinematic results showed that the peak resultant lower torso acceleration was an average of -18 g's for the 11.1 m/s (40 kph) tests and -6.2 g's for the 5.6 m/s (20 kph) tests. The lumbar axial rotation excursions had the largest relative values compared to normal physiologic ranges of motion. Flexion extension and lateral bending were well within normal range.

Inverse dynamic methods were used to characterize the forces at the low back during during the frontal impacts. The mean peak anterior shear forces were at 2913 N (655 pounds). The mean peak axial compressive forces were 3461 N (778 pounds) and the mean peak lateral shear forces were 773 N (174 pounds). The results showed that the anterior shear forces have the most potential to be injurious.

Anthropometric test dummies have been used extensively in academics and in industry as a means of testing the human response to impact. The biomechanical response of the lumbar spine of the H3 and Thor crash test dummies were compared to that of the PMHS. Comparisons showed that the accelerations of the pelvic centers of mass of the PMHS and the H3 were significantly lower than the Thor-NT. The lumbar forces for H3 were lower than the PMHS. The Thor thoracic forces were also significantly lower than the PMHS thoracic forces. This study showed that more work needs to be done to improve the biofidelity of H3 and Thor crash test dummies.