Thoracic and lumbar spinal impact tolerance

Thoracolumbar injuries resulting from motor vehicle accidents, falls, and assaults have a high risk of morbidity and mortality. However, there are no biomechanically based standards that address this problem.

This study used four cadaveric porcine specimens as a model for direct spinal impact injuries to humans to determine an appropriate injury tolerance value. The anthropometric parameters of these specimens are compared with values found in a large human cadaveric dataset. Each specimen was subjected to five impacts on the dorsal surface of the lower thorax and abdomen.

The injuries ranged from mild spinous process fractures to endplate fractures with anterior longitudinal ligament (ALL) transactions with a maximum AIS=3. The average peak reaction force for the thoracic failure tests was 4720+/-1340 N, and the average peak reaction force for the lumbar failure tests was 4650+/-1590 N.

When scaled to human values using anthropometric parameters determined in this study, the force at which there is a 50% risk of injury is 10,200+/-3900 N. This value favorably compares to that found in the existing literature on isolated vertebral segments.

After demonstrating that the porcine model can be used as a spinal impact model for the human, the resulting injury risk value can be used in determining new standards for human injury risk or in guiding the design of safety equipment for the back.