Grade

Description

I

Screw completely contained in the pedicle.

II

Screw perforates the lateral wall of the pedicle but the tip is completely contained in the vertebral body.

III

Screw pierces the lateral wall of the pedicle.

IV

Perforation of the medial or inferior wall of the pedicle.

V

Perforation the vertebral body and endangers the spinal cord, root or vessel, requires intervention.