Insertion Angle of Pedicle Screws in the Subaxial Cervical Spine: The Analysis of Computed Tomography-Navigated Insertion of Pedicle Screws

Abstract

Four orthopedic spine surgeons measured the radiological parameters of pedicle screws in the cervical spine using a postoperative computed tomography (CT) scan. Purpose: This study analyzed the insertion angle of CT-navigated insertion of pedicle screws in the subaxial cervical spine and classified them according to their position. Overview of Literature: Overall, a pedicle transverse angle of 33.6°-50.2° with a mean angle of 45° relative to the midline has been reported in the literature. Methods: The insertion angles of 87 pedicle screws inserted using CT-based navigation in the subaxial cervical spine were measured in the postoperative CT. The screw positioning was determined according to the modified Gertzbein and Robbins classification. Results: Total 89.3% (n=78) of the pedicle screws inserted using CT-based navigation showed good placement. The mean insertion angle of the pedicle screws that showed good positioning was 29.9°±9.9°. The pedicle screws showing bad positioning had a mean insertion angle of 26.8°±10.5° (p=0.157). The interobserver reliability showed a reliable measurement intraclass correlation coefficient: 0.994 (95% confidence interval, 0.992-0.996). Conclusions: The present results show that the insertion angle of the pedicle screws in the subaxial cervical spine was smaller than the actual pedicle transverse angle, as per the literature. One reason for this discrepancy could be that the navigation systems allow the insertion of cervical pedicle screws with a lower convergence.

Clinical efficiency of operating room-based sliding gantry CT as compared to mobile cone-beam CT-based navigated pedicle screw placement in 853 patients and 6733 screws

“…While the accuracy of pedicle screw placement and revision rates of the present study are comparable to earlier publications on navigated pedicle screws, the differences of durations are difficult to compare since measurements, subgroups, and the complexity of surgeries vary across publications. With a special regard to instrumentation of the cervical spine and cervicothoracic junction, the present study's results show one of the largest cohorts with CT-navigated cervical pedicle screws [23][24][25][26]. The present subanalysis showed less differences for the comparison of the ORCT and CBCT group.…”

Medial Pedicle Pivot Point Using Preoperative Computed Tomography Morphometric Measurements for Cervical Pedicle Screw Insertion: A Novel Technique and Case Series

“…Since the screw diameter was 3.5 mm, following the strict surgical indication of a PD ≥3.5 mm was important for our technique. Interestingly, most previously reported techniques did not consider PD when planning surgery, which may have resulted in a higher rate of pedicle breach or pedicle fractures when the screws were inserted [11,15,19,22,24]. In earlier studies regarding pedicle insertion, the lateral direction was most common.…”

“…Currently, with technological advances such as computer assisted navigation (CAN) systems such as Stealth Station Spine Surgery Imaging and Surgical Navigation with Oarm (Medtronic, Minneapolis, MN, USA) or Ziehm Vision FD Vario 3-D with NaviPort 2 of 12 integration (Ziehm Imaging, Orlando, FL, USA), it has become possible to contribute to accurate posterior fixation [11,12]. However, since CAN system requires considerable expensive equipment from an economic point of view, there is an environmental limitation that all medical institutions cannot be equipped with a CAN system.…”

Navigation for surgical treatment of disorders of the cervical spine – A systematic review

“…22,23 Other studies using ioCT only or in comparison with freehand placement reported pedicle screw misplacement rates ranging between 2 and 12%. [17][18][19]25,26 This appears to be slightly superior to intraoperative 3D fluoroscopy with pedicle screw misplacement rates ranging between 3 and 20% [27][28][29][30][32][33][34][35][36][37][38] ; direct comparisons, however, are lacking.…”