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. 2024 Feb 29;24(1):74.
doi: 10.1186/s12893-024-02358-7.

Free-hand technique of C7 pedicle screw insertion using a simply defined entry point without fluoroscopic guidance for cervical spondylotic myelopathy patients with C3 to C6 instrumented by lateral mass screws: a retrospective cohort study

Jun Jiang #  1 , Chen-Yu Song #  1 , Zheng-Zheng Wu  1 , Zuo-Zhi Xie  1 , Bo Shi  1 , Tao Xu  1 , Han Wang  2 , Yong Qiu  1 , Bin Wang  1 , Ze-Zhang Zhu  1 , Yang Yu  3
Affiliations

Free-hand technique of C7 pedicle screw insertion using a simply defined entry point without fluoroscopic guidance for cervical spondylotic myelopathy patients with C3 to C6 instrumented by lateral mass screws: a retrospective cohort study

Jun Jiang et al. BMC Surg. .

Abstract

Background: Nowadays, both lateral mass screw (LMS) and pedicle screw were effective instrumentation for posterior stabilization of cervical spine. This study aims to evaluate the feasibility of a new free-hand technique of C7 pedicle screw insertion without fluoroscopic guidance for cervical spondylotic myelopathy (CSM) patients with C3 to C6 instrumented by lateral mass screws.

Methods: A total of 53 CSM patients underwent lateral mass screws instrumentation at C3 to C6 levels and pedicle screw instrumentation at C7 level were included. The preoperative 3-dimenional computed tomography (CT) reconstruction images of cervical spine were used to determine 2 different C7 pedicle screw trajectories. Trajectory A passed through the axis of the C7 pedicle while trajectory B selected the midpoint of the base of C7 superior facet as the entry point. All these 53 patients had the C7 pedicle screw inserted through trajectory B by free-hand without fluoroscopic guidance and the postoperative CT images were obtained to evaluate the accuracy of C7 pedicle screw insertion.

Results: Trajectory B had smaller transverse angle, smaller screw length, and smaller screw width but both similar sagittal angle and similar pedicle height when compared with trajectory A. A total of 106 pedicle screws were inserted at C7 through trajectory B and only 8 screws were displaced with the accuracy of screw placement as high as 92.5%.

Conclusion: In CSM patients with C3 to C6 instrumented by LMS, using trajectory B for C7 pedicle screw insertion is easy to both identify the entry point and facilitate the rod insertion.

Keywords: Cervical; Computed tomography; Pedicle screw; Trajectory.

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Conflict of interest statement

The author declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Figures

Fig. 1
Fig. 1
Illustration of two different trajectories for C7 pedicle screw insertion. Axis of cylinder A passed through the center of C7 pedicle while axis of cylinder B penetrated the posterior aspect of C7 at the midpoint of the base of superior facet
Fig. 2
Fig. 2
Illustration of trajectory A. Trajectory A passed through the center of C7 pedicle on axial, sagittal and coronal planes. ɑ: transverse angle; β: sagittal angle; l: screw length; m: sagittal height; n: screw width
Fig. 3
Fig. 3
Illustration of trajectory B. Ep B was located at the midpoint of the base of C7 superior facet. ɑ: transverse angle; β: sagittal angle; l: screw length; m: sagittal height; n: screw width
Fig. 4
Fig. 4
d1: the horizontal distance between Ep A and Ep B; d2: the vertical distance between Ep A and Ep B. The value was positive if Ep A was above Ep B and negative if Ep A was below Ep B
Fig. 5
Fig. 5
The entry point of C7 pedicle screw insertion through trajectory B was keep in line with the entry points of lateral mass screws from C3 to C6, which facilitated the rod insertion
See this image and copyright information in PMC

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