Gertzbein and Robbins classification

Last revised by Kieran Kusel on 12 Feb 2021

The Gertzbein and Robbins classification assesses the position of transpedicular screws.


Transpedicular screw position is graded from A to E based on the extent by which the screw breaches the cortex of the pedicle 1-3:

  • A: fully intrapedicular position without breach of the pedicle cortex
  • B: exceeding the pedicle cortex <2 mm
  • C: exceeding the pedicle cortex 2-4 mm
  • D: exceeding the pedicle cortex 4-6 mm
  • E: exceeding the pedicle cortex >6 mm or is outside of the pedicle

Grade A and B can be a considered satisfactory operation result 3. In grade C to E, neurological symptoms may occur and can be evaluated as an unsatisfactory surgical result 1,3.

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