Gertzbein-Robbins classification

Gertzbein-Robbins classification. The grading system reflects the deviation of the screw from the “ideal” intrapedicular trajectory. The grades are as follows:

Grade A, an intrapedicular screw without breach of the cortical layer of the pedicle;

Grade B, a screw that breaches the cortical layer of the pedicle but does not exceed it laterally by more than 2 mm;

Grades C and D, penetration of less than 4 and 6 mm, respectively (arrow);

Grade E, screws (arrows) that do not pass through the pedicle or that, at any given point in their intended intrapedicular course, breach the cortical layer of the pedicle in any direction by more than 6 mm.

Note that the screw that was graded as D has a deviation of more than 4 mm from the intrapedicular directory. Modified with permission from Schatlo et al: J Neurosurg Spine 20:636-243, 2014.

From: https://www.researchgate.net/figure/Gertzbein-Robbins-classification-The-grading-system-reflects-the-deviation-of-the-screw_fig1_316649934