ABSTRACT
Objective To discuss the technique and value of preoperative reformatting with three-dimensional computed tomography technique for C_2 pedicle screw track.Methods GE Light Speed 16 Pro spinal CT scans of 15 adult dry vertebrae were loaded into an imaging station (software ADW4.2).Two methods of C_2 pedicle screw techniques were analyzed through virtual screw trajectory by VR (volume rendering) and MPR (multiple planar reformatting) techniques,in method A,screw entry point was the intersection between the media-vertical and the cranial line of C_2 inferior facet joint,in method B,the screw track was from the cranial and medial quadrant of the dorsal part of C_2 inferior facet joint.Results The screw track could be observed dynamically from any plane.Two vertebrae were ob- served with smaller height in isthmus and the medial edge of the transverse foramen since no space was a- vailable for the screw.The screw trajectories data were compared between method A and method B,which showed that the angles towards the cephalad (in sagittal plane) and midline (in transverse plane) were bigger in method A than in method B (P＜0.05,0.01),but the safe screw diameter was smaller in method A than in method B (P＜0.05),and there was no difference of the screw length between the two methods(P＜0.05 ).Conclusion In this research,the individual C_2 pedicle screw entry points, screw diameter and security screw angle can be simulated,and the screw track can be observed dynami- cally to make sure if it transits the bone structure completely.Preoperative three-dimensional computed tomography reformatting for pedicle screw track is of great value in clinical and basic researches.