Fig. 3

The stress nephogram of the Schanz pedicle screw for the L1 severe fractures after T12 and L2 pedicle screw fixation during anterior flexion. Red is the maximum stress. The maximum stress occurred at the interface of the proximal pedicle and cortical bone, and the stress of the upper screw is greater than that of the lower screw. A1–A6 0°, B1–B6 5°, C1–C6 10°, and D1–D6 15°. There are 6 models in each group