Table 1 Summary of computed tomography grading criteria
Grade | Accuracy of PPSP according to Neo et al. |
|---|---|
0 | No deviation; the screw was contained in the pedicle |
1 | Deviation < 2 mm (i.e., less than half of the screw diameter) |
2 | Deviation > 2 and < 4 mm |
3 | Deviation > 4 mm (i.e., complete deviation) |