Fig. 7

Axial (Z-axis) displacement nephogram of the micro-motion of vertebral defect area of Schanz pedicle screw for L1 severe fracture during posterior extension. Red is the maximum displacement upward, and blue is the maximum displacement downward. A1–A6 0°, B1–B6 5°, C1– C6 10°, and D1–D6 15°. There are 6 models in each group