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Cervical lateral mass screw fixation without fluoroscopic control: analysis of risk factors for complications associated with screw insertion.

Inoue S, Moriyama T, Tachibana T, Okada F, Maruo K, Horinouchi Y, Yoshiya S - Arch Orthop Trauma Surg (2012)

Bottom Line: As intraoperative screw-associated complications, 9.6 % of the screws were found to contact with or breach the vertebral artery foramen.This complication was associated with a significantly lower trajectory angles in the sagittal plane, predominantly at C6 level (69.2 %).In the analysis of potential risk factors for violation of the VA foramen as well as FV during screw insertion, the former incidence was significantly related to the screw trajectory angle (lack of lateral angulation) in the axial plane, while the latter incidence was related to a poor screw trajectory angle in the sagittal plane.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedic Surgery, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo, Japan. inoshin@hyo-med.ac.jp

ABSTRACT

Objective: To examine the outcome of cervical lateral mass screw fixation focusing on analysis of the risk factors for screw-related complications.

Methods: Ninety-four patients who underwent posterior cervical fixation with a total of 457 lateral mass screws were included in the study. The lateral mass screws were placed using a modified Magerl method. Computed tomographic (CT) images were taken in the early postoperative period in all patients, and the screw trajectory angle was measured on both axial and sagittal plane images.

Results: In the postoperative CT analysis for the screw trajectory, 56.5 % of the screws were directed within the acceptable range (within 21-40° on both axial and sagittal planes). As intraoperative screw-associated complications, 9.6 % of the screws were found to contact with or breach the vertebral artery foramen. In this group, the screw trajectory angle on axial plane was significantly lower than in the group without contact. Facet violation was observed in 13 screws (2.8 %). This complication was associated with a significantly lower trajectory angles in the sagittal plane, predominantly at C6 level (69.2 %). In the patient chart review, no serious neurovascular injuries were documented.

Conclusions: In the analysis of potential risk factors for violation of the VA foramen as well as FV during screw insertion, the former incidence was significantly related to the screw trajectory angle (lack of lateral angulation) in the axial plane, while the latter incidence was related to a poor screw trajectory angle in the sagittal plane.

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Determination of orientation of screw trajectory in the image analysis. Axial plane: the angle between the axial screw trajectory and the line perpendicular to the tangential line behind the vertebral body. Sagittal plane: the angle between the sagittal trajectory and the line perpendicular to the tangential line behind the lateral mass
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Fig2: Determination of orientation of screw trajectory in the image analysis. Axial plane: the angle between the axial screw trajectory and the line perpendicular to the tangential line behind the vertebral body. Sagittal plane: the angle between the sagittal trajectory and the line perpendicular to the tangential line behind the lateral mass

Mentions: For all the included patients, CT examinations were performed within 3 weeks after the surgery. The screw trajectory angle was measured on both axial and sagittal planes following the method described by Seybold et al. [29]. Among the serial CT images taken with a slice thickness of 3 mm, the axial slices including the VA foramen and sagittal slices including the facet joint were selected for each of the cervical levels. Violation of the VA foramen as well as the facet joint by the screw was assessed on those images. Screw trajectory was measured using a ruler and a goniometer on the printed CT images showing the screw as well as the bony landmarks (Fig. 2). The acceptable range of the screw trajectory angle was defined within 21–40° on both axial and sagittal planes.Fig. 2


Cervical lateral mass screw fixation without fluoroscopic control: analysis of risk factors for complications associated with screw insertion.

Inoue S, Moriyama T, Tachibana T, Okada F, Maruo K, Horinouchi Y, Yoshiya S - Arch Orthop Trauma Surg (2012)

Determination of orientation of screw trajectory in the image analysis. Axial plane: the angle between the axial screw trajectory and the line perpendicular to the tangential line behind the vertebral body. Sagittal plane: the angle between the sagittal trajectory and the line perpendicular to the tangential line behind the lateral mass
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3376780&req=5

Fig2: Determination of orientation of screw trajectory in the image analysis. Axial plane: the angle between the axial screw trajectory and the line perpendicular to the tangential line behind the vertebral body. Sagittal plane: the angle between the sagittal trajectory and the line perpendicular to the tangential line behind the lateral mass
Mentions: For all the included patients, CT examinations were performed within 3 weeks after the surgery. The screw trajectory angle was measured on both axial and sagittal planes following the method described by Seybold et al. [29]. Among the serial CT images taken with a slice thickness of 3 mm, the axial slices including the VA foramen and sagittal slices including the facet joint were selected for each of the cervical levels. Violation of the VA foramen as well as the facet joint by the screw was assessed on those images. Screw trajectory was measured using a ruler and a goniometer on the printed CT images showing the screw as well as the bony landmarks (Fig. 2). The acceptable range of the screw trajectory angle was defined within 21–40° on both axial and sagittal planes.Fig. 2

Bottom Line: As intraoperative screw-associated complications, 9.6 % of the screws were found to contact with or breach the vertebral artery foramen.This complication was associated with a significantly lower trajectory angles in the sagittal plane, predominantly at C6 level (69.2 %).In the analysis of potential risk factors for violation of the VA foramen as well as FV during screw insertion, the former incidence was significantly related to the screw trajectory angle (lack of lateral angulation) in the axial plane, while the latter incidence was related to a poor screw trajectory angle in the sagittal plane.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedic Surgery, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo, Japan. inoshin@hyo-med.ac.jp

ABSTRACT

Objective: To examine the outcome of cervical lateral mass screw fixation focusing on analysis of the risk factors for screw-related complications.

Methods: Ninety-four patients who underwent posterior cervical fixation with a total of 457 lateral mass screws were included in the study. The lateral mass screws were placed using a modified Magerl method. Computed tomographic (CT) images were taken in the early postoperative period in all patients, and the screw trajectory angle was measured on both axial and sagittal plane images.

Results: In the postoperative CT analysis for the screw trajectory, 56.5 % of the screws were directed within the acceptable range (within 21-40° on both axial and sagittal planes). As intraoperative screw-associated complications, 9.6 % of the screws were found to contact with or breach the vertebral artery foramen. In this group, the screw trajectory angle on axial plane was significantly lower than in the group without contact. Facet violation was observed in 13 screws (2.8 %). This complication was associated with a significantly lower trajectory angles in the sagittal plane, predominantly at C6 level (69.2 %). In the patient chart review, no serious neurovascular injuries were documented.

Conclusions: In the analysis of potential risk factors for violation of the VA foramen as well as FV during screw insertion, the former incidence was significantly related to the screw trajectory angle (lack of lateral angulation) in the axial plane, while the latter incidence was related to a poor screw trajectory angle in the sagittal plane.

Show MeSH
Related in: MedlinePlus