Dataset Information

Establishing the Injury Severity of Subaxial Cervical Spine Trauma: Validating the Hierarchical Nature of the AO Spine Subaxial Cervical Spine Injury Classification System.

ABSTRACT:

Study design

Global cross-sectional survey.

Objective

The aim of this study was to validate the AO Spine Subaxial Cervical Spine Injury Classification by examining the perceived injury severity by surgeon across AO geographical regions and practice experience.

Summary of background data

Previous subaxial cervical spine injury classifications have been limited by subpar interobserver reliability and clinical applicability. In an attempt to create a universally validated scheme with prognostic value, AO Spine established a subaxial cervical spine injury classification involving four elements: injury morphology, facet injury involvement, neurologic status, and case-specific modifiers.

Methods

A survey was sent to 272 AO Spine members across all geographic regions and with a variety of practice experience. Respondents graded the severity of each variable of the classification system on a scale from zero (low severity) to 100 (high severity). Primary outcome was to assess differences in perceived injury severity for each injury type over geographic regions and level of practice experience.

Results

A total of 189 responses were received. Overall, the classification system exhibited a hierarchical progression in subtype injury severity scores. Only three subtypes showed a significant difference in injury severity score among geographic regions: F3 (floating lateral mass fracture, P = 0.04), N3 (incomplete spinal cord injury, P = 0.03), and M2 (critical disk herniation, P = 0.04). When stratified by surgeon experience, pairwise comparison showed only two morphological subtypes, B1 (bony posterior tension band injury, P = 0.02) and F2 (unstable facet fracture, P = 0.03), and one neurologic subtype (N3, P = 0.02) exhibited a significant difference in injury severity score.

Conclusion

The AO Spine Subaxial Cervical Spine Injury Classification System has shown to be reliable and suitable for proper patient management. The study shows this classification is substantially generalizable by geographic region and surgeon experience, and provides a consistent method of communication among physicians while covering the majority of subaxial cervical spine traumatic injuries.Level of Evidence: 4.

SUBMITTER: Schroeder GD

PROVIDER: S-EPMC8057527 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Introduction The cervical spine is a highly mobile segment of the spinal column, liable to a variety of diseases and susceptible to trauma. It is a complex region where many vital structures lie in close proximity. Lateral mass screw fixation has become the method of choice in stabilizing subaxial cervical spine among other posterior cervical fixation techniques whenever the posterior elements are absent or compromised. Objective This study examined cervical specimens of cadavers and cervical computed tomography (CT) scans to minimize as much as possible complications of cervical lateral mass screw placement such as vertebral artery or nerve root injuries, facet joint violations, or inadequate placement. Methods Forty normal cervical CT scans, obtained from the emergency unit as part of the trauma workup, were included in this study plus 10 cervical cadaveric specimens obtained from the Alexandria Neuro-anatomy laboratory. There were three fixed parameters for screw insertion in this study. First, the point of screw insertion was the midpoint of the lateral mass; it was the crossing point between the sagittal and axial planes of the posterior cortex of the lateral mass. Second, the direction of the screw in the craniocaudal plane was 30 degrees cranially to avoid facet joint penetration. Third, the exit point of the screw was located on the ventral cortex of the lateral mass just lateral to the root of the transverse process in the midaxial cut of each lateral mass, to make a sound bicortical fixation without injuring the vertebral artery or the nerve root. The selected screw trajectory in this study was the line drawn between the inlet and exit points. The depth and width of the lateral mass of the cervical vertebrae from C3 to C7 were measured as well as the angle of screw trajectory from the sagittal plane. All these measures were applied on the cadaveric specimens to make sure that no injury to the vertebral artery, nerve root, or facet joint occurred. Results As regards the collected measurements of the lateral mass of all subaxial cervical vertebrae, the study revealed that the average depth of the lateral mass was 12.83 ± 1.28 mm. The average width of the lateral mass was 11.92 ± 0.96 mm. The average divergent angle of bicortical screw insertion without injury to the vertebral artery or the nerve root was 19.51 ± 1.83 degrees. As regard the cadaveric specimens, based on all the collected measurements taken from the CT scans, there was no reported injury to the vertebral arteries or nerve roots or penetration to the facet joints. Conclusion Lateral mass fixation can be applied easily and safely for all levels of subaxial cervical spine from C3 to C6 with the following parameters: (1) the point of entry is the midpoint of the lateral mass; (2) the screw trajectory is directed 30 degrees cranially and 20 degrees laterally; (3) the screw length is 13 to 15 mm.