Abstract
Objective: It is important and helpful for surgeons to understand the correlation between spinal anatomy and screw trajectory before surgery. We aimed to assess a simple technique using 3D imaging software available on the hospital intranet for visual and quantitative feedback to prepare surgeons for an appropriate entry point and safe trajectory when placing cervical screws. Methods: A total of 59 cervical screws were inserted from C1 to T1 in 12 consecutive patients using this technique. First, a single CT optimal slice was selected from 3D CT images of the cervical spine to determine the intervals of bilateral entry points and lateral angle. Next, this 3D image was rotated to the lateral angle. Finally, bone was cut out on the entry point using subtractive manipulation, which removed the core of the pedicle or lateral mass. Screw trajectory was indicated, and surgeons could assess the correlation between surface landmarks, spinal anatomy, and screw trajectory. Posterior cervical fusion was performed using fluoroscopy. Postoperative outcomes and incidence of complications were retrospectively assessed. Results: One perforation (1.4%) was identified on postoperative CT images. No vascular injuries occurred. Differences in the intended entry point location and lateral angle of the screw from actual postoperative values were 1.49 ± 1.23 mm and 5.46。 ± 4.46。, respectively. Conclusions: A novel 3D CT imaging assessment underwent in cervical screw fixation. This technique is easily accessible on the hospital intranet and provides training in cervical screw placement for fellows. Surgeons can simulate screw placement and share surgical strategy.
Highlights
We propose a simple technique using 3D software to allow for an appropriate entry point and safe trajectory on the hospital intranet monitor
The targeted entry point is 1 - 2 mm medial and 1 - 2 mm inferior to the lateral mass center, and the screw trajectory is parallel to the facet joint under fluoroscopy
We propose a simple preoperative assessment for determining an ideal trajectory for cervical screw placement
Summary
A 3D CT scan of the cervical spine of the patient is first obtained using 1-mm slice thickness (Aquilion 16, Toshiba Medical Systems Corp.). Three multiplanar reformation planes (sagittal, coronal, and axial) are shown for the indicated location Surgeons can access this workstation via the hospital intranet. The intervals of bilateral entry points and left and right lateral angles are obtained. The locations of left and right entry points are marked on reconstructed 3D CT images. The intervals of entry points indicate the location of the left and right entry points This 3D image is rotated to the selected lateral angle (Figure 2). Screw trajectory is indicated by a green line, and viewed in the axial, coronal, and sagittal planes (Figure 3). If the virtual screw trajectory deviates from the pedicle and lateral mass, rotation and entry points can be readjusted. Postoperative radiographs and CT scans were obtained (Figure 5)
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