Abstract： Objective To investigate the mechanism associated with thoracolumbar burst fractures.Methods Stress distribution of the spine in the upright, flexion and extension positions was analyzed using a three-dimensional finite element model of the spinal motion segment. Results Stress concentration was noted at the pedicle and posterosuperior part of the vertebral body near the pedicle.Conclusion Stress concentration of the spine may be implicated in the biomechanical mechanism underlying thoracolumbar burst fractures. Burst fractures are defined as injuries of both the anterior and middle