Subaxial Cervical Spine Injuries: WFNS Spine Committee Recommendations

Abstract

To formulate specific guidelines for the recommendation of subaxial cervical spine injuries concerning classification, management, posttraumatic locked facets and vertebral artery injury. Computerized literature was searched on PubMed and google scholar database from 2009 to 2020. For classification, keywords "Sub Axial Cervical Spine Classification," resulting in 22 articles related to subaxial cervical spine injury classification system (SLICS) system and 11 articles related to AO (Arbeitsgemeinschaft für Osteosynthesefragen, German for "Association for the Study of Internal Fixation") Spine system. The literature search yielded 210 and 78 articles on "management of subaxial cervical spine injuries" and the role of "SLICS" and "AO Spine" respectively. Keywords "management of traumatic facet locks" were searched and closed reduction, traction, approaches and techniques were studied. "Vertebral artery injury and cervical fracture" exhibited 2,328 references from the last 15 years. The objective was to identify the appropriate diagnostic tests and optimal treatment. Up-to-date information was reviewed, and statements were produced to reach a consensus in 2 separate consensus meetings of World Federation of Neurosurgical Societies (WFNS) Spine Committee. The statements were voted and reached a positive or negative consensus using Delphi method. Based on the most relevant literature, panelists in Moscow consensus meeting conducted in May 2019 drafted the statements, and after a preliminary voting session, the consensus was identified on various statements. Another meeting was conducted at Peshawar in November 2019, where in addition to previous statements, few other statements were discussed and voted. Specific recommendations were then formulated guiding classification, management, locked facets and vertebral artery injuries. This review summarizes the WFNS Spine Committee recommendations on subaxial cervical spine injuries.

Keywords: AO Spine; Classification and management; Locked facet; Subaxial cervical spine; Subaxial cervical spine injury classification system; Vertebral artery injury.

Fig. 1.

literature search for classification system of subaxial cervical spine injury. SLICS, subaxial cervical spine injury classification system; AO, Arbeitsgemeinschaft für Osteosynthesefragen (German for “Association for the Study of Internal Fixation”).

Fig. 2.

Sagittal views of computed tomography and magnetic resonance imaging depicting the 4 components of morphology in the subaxial cervical spine injury classification and severity scale. (Permission taken from corresponding author and publisher Wolters Kluwer) [7].

Fig. 3.

AO spine classification system for subaxial cervical spine injuries (©AO Foundation, AO Spine, Switzerland) [23-26,32]. (A) Morphological classification of AO Spine. (B) Algorithm for classifying injuries, and (C) Neurology and Modifiers.

Fig. 4.

Literature search for management protocols of subaxial cervical spine injury.

Fig. 5.

(A) X-ray cervical spine lateral view showing vertical compression fracture stage 3. (B) Sagittal T2-weighted magnetic resonance imaging cervical spine showing vertical compression. (C) X-ray cervical spine lateral view showing surgical management of vertical compression stage 3 injury. Reprinted from Zaveri and Das. Indian J Orthop 2017;51:633 [39].

Fig. 6.

Stages of a compressive flexion injury wedge compression (A), anteroinferior beaking (B), teardrop fracture (C), retrolisthesis of the posterosuperior fragment by < 3 mm (D), retrolisthesis > 3 mm (E).

Fig. 7.

Stages of distractive flexion injury: flexion sprain (A), unifacet dislocation (B), bifacet dislocation with antero-listhesis < 50% (C), anterolisthesis > 50% (D), complete spondyloptosis (E).

Fig. 8.

Stages of a compressive extension injury: unilateral vertebral arch fracture (A), bilateral vertebral arch fractures (B), bilateral vertebral arch fractures with the anterior extension of the fracture (C), but spinal alignment maintained, dissociation between anterior and posterior vertebral columns with progressive anterior translation (D, E).

Fig. 9.

Algorithm for management of unstable reduced fractures of subaxial spine.

Fig. 10.

Algorithm for management of displaced unstable fractures of subaxial spine.

Fig. 11.

Anterior approach (facet lock reduction and anterior fixation). (A) C6/7 facet dislocation (lock). (B) Traction reduction. (C) Anterior stabilization with interbody autograft.

Fig. 12.

Irreducible locked facet management by combined approach. (A) C5/6 facet lock. (B) Magnetic resonance imaging showing large disc prolapse. (C) Irreductible after dissectomy through anterior approach. (D) Patient rotated and locked facet exposed. (E) Upper half of jumped facet drilled out, reduction achieved and posterior stabilization done. (F) After posterior reduction patient again rotated and anterior stabilization done along with autograft.

Fig. 13.

Diagrammatic representation of normal transverse foramen (A) in comparison to vertebral artery injury (B) secondary to displaced fracture > 1 mm into the left transverse foramen in axial view. Black arrow indicates the fracture fragments with disruption of the left transverse foramen.