Dynamic finite element analysis of the lumbar spine injury on collision

The incident rate of spinal cord injury is about 1200 cases per year in Taiwan, mainly due to the motorcycle accident. About 30% of the spinal cord injury and bone fracture is located at the lumbar spine region. The purpose of this study was to investigate the possible lumbar spine injury pattern in four types of car-motorcycle accidents. A ligamentous finite element Ll to L5 lumbar spine model with spinal canal was modeled and analyzed using LSDYNA3D. The simulation included: rear impact, front impact, lateral impact and side impact. The results showed that the severest bone fracture was in the case of frontal impact, the max principle stress of 305 Mpa was located at the pedicle base of L5. The frontal impact also leaded the largest right-lateral disc bulge at the L1-2, the bulge was 4.84 mm. The maximum spinal canal stenosis of 2.74 mm was due to the first mode of spinal column buckling in the simulation of lateral impact at the L1. The combination impact forces of lateral bending and compression such as the frontal impact, or lateral bending and torsion (lateral impact) is the vital condition to cause spinal cord injury and vertebral body fracture.