BACKGROUND: Based on the phenomenon that most thoracolumbar primary fracture line passes the center of the pedicle, we proposed an injury mechanism model to evaluate. METHODS: Consecutive patients with thoracolumbar fractures treated operatively between October 2019, and December 2020 were analyzed retrospectively. Demographic and spinal radiographical parameters were measured and recorded. Pedicle hyperintensity on T2-weighted sagittal MR images was labeled. We examined the relationship between the course of the line (Radius) connecting the center of the pedicle of the injured vertebra and the IAR and orientation of the thoracolumbar primary fracture line. A partial correlation test was calculated to find correlations between demographic and spinal radiographical parameters. Nonlinear regression analysis was run with the Radius as the dependent variable and the other spinal kyphosis parameters as the independent variables to verify this model. RESULTS: Ninety-seven patients with 104 thoracolumbar fractures were included in this study. Ninety-four (90.4%) thoracolumbar fractures showed a high signal on MRI T2 through the pedicle. Involvement of the center of the pedicle was distributed among most AOTL Type A and Type B thoracolumbar fractures. In total, 92.3% of primary vertebral fracture lines followed the Radius of the model (r2 = 0.940). CONCLUSIONS: We provide a simple and quantifiable spinal instantaneous injury mechanism model for thoracolumbar fractures. Specifically, most AOTL type A and B thoracolumbar primary fracture line conforms to this model.