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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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Related in: MedlinePlus

Violation of the edge of VA foramen by the left lateral mass screw is identified. The screw trajectory angle in the axial plane is 5°
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Fig3: Violation of the edge of VA foramen by the left lateral mass screw is identified. The screw trajectory angle in the axial plane is 5°

Mentions: Analysis of the axial image at each level revealed contact of the screw with the edge of the VA foramen in 8.5 % (39 of 457) of the screws. Moreover, 5 screws (1.1 %) were observed to violate the edge of the foramen (Fig. 3). In total, 44 screws (9.6 %) were classified as the contact group, while no contact or violation was observed on CT images in the remaining 413 group 2 screws (90.4 %). In the analysis of the factors related to the contact or violation of the screw, it was shown that the axial trajectory angle in the contact group (18.5°) was significantly lower than the angle in the non-contact group (26.7°) with a statistical significance (P < 0.0001). When the axial trajectory angle in the contact group was compared among the levels, no difference was detected. In the comparison of the sagittal projection angle and screw length between the contact and non-contact groups, no significant difference was observed.Table 3


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)

Violation of the edge of VA foramen by the left lateral mass screw is identified. The screw trajectory angle in the axial plane is 5°
© Copyright Policy
Related In: Results  -  Collection

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

Fig3: Violation of the edge of VA foramen by the left lateral mass screw is identified. The screw trajectory angle in the axial plane is 5°
Mentions: Analysis of the axial image at each level revealed contact of the screw with the edge of the VA foramen in 8.5 % (39 of 457) of the screws. Moreover, 5 screws (1.1 %) were observed to violate the edge of the foramen (Fig. 3). In total, 44 screws (9.6 %) were classified as the contact group, while no contact or violation was observed on CT images in the remaining 413 group 2 screws (90.4 %). In the analysis of the factors related to the contact or violation of the screw, it was shown that the axial trajectory angle in the contact group (18.5°) was significantly lower than the angle in the non-contact group (26.7°) with a statistical significance (P < 0.0001). When the axial trajectory angle in the contact group was compared among the levels, no difference was detected. In the comparison of the sagittal projection angle and screw length between the contact and non-contact groups, no significant difference was observed.Table 3

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