Fig. 1From: Intraoperative 3D imaging with cone-beam computed tomography leads to revision of pedicle screws in dorsal instrumentation: a retrospective analysisAssessment of the pedicle screw position using the Gertzbein–Robbins–Robbins classification [9]. Marking of the bony pedicle borders by an ellipse. Then determine the maximum screw distance from the (in this case lateral) pedicle borderBack to article page