Two-Nation Comparison of Classification and Treatment of Subaxial Cervical Spine Fractures: An Internet-Based Multicenter Study Among Spine Surgeons

Validation of the Hierarchical Nature of the AO Spine Sacral Classification and the Development of the Sacral AO Spine Injury Score

STUDY DESIGN

Global cross-sectional survey.

OBJECTIVE

The objective of this study was to validate the hierarchical nature of the AO Spine Sacral Classification System and develop an injury scoring system.

SUMMARY OF BACKGROUND DATA

Although substantial interobserver and intraobserver reliability of the AO Spine Sacral Classification System has been established, the hierarchical nature of the classification has yet to be validated.

METHODS

Respondents numerically graded each variable within the classification system for severity. Based on the results, a Sacral AO Spine Injury Score (AOSIS) was developed.

RESULTS

A total of 142 responses were received. The classification exhibited a hierarchical Injury Severity Score (ISS) progression (A1: 8 to C3: 95) with few exceptions. Subtypes B1 and B2 fractures showed no significant difference in ISS (B1 43.9 vs. B2 43.4, P =0.362). In addition, the transitions A3→B1 and B3→C0 represent significant decreases in ISS (A3 66.3 vs. B1 43.9, P <0.001; B3 64.2 vs. C0 46.4, P <0.001). Accordingly, A1 injury was assigned a score of 0. A2 and A3 received scores of 1 and 3 points, respectively. Posterior pelvic injuries B1 and B2 both received a score of 2. B3 received a score of 3 points. C0, C1, C2, and C3 received scores of 2, 3, 5, and 6 points, respectively. The scores assigned to neurological modifiers N0, N1, N2, N3, and NX were 0, 1, 2, 4, and 3, respectively. Case-specific modifiers M1, M2, M3, and M4 received scores of 0, 0, 1, and 2 points, respectively.

CONCLUSIONS

The results of this study validate the hierarchical nature of the AO Spine Sacral Classification System. The Sacral AOSIS sets the foundation for further studies to develop a universally accepted treatment algorithm for the treatment of complex sacral injuries.

LEVEL OF EVIDENCE

Level IV-Diagnostic.

The Subaxial Cervical AO Spine Injury Score

STUDY DESIGN

Global cross-sectional survey.

OBJECTIVE

To develop an injury score for the AO Spine Subaxial Cervical Spine Injury Classification System.

METHODS

Respondents numerically graded each variable within the classification system for severity. Based on the results, and with input from the AO Spine Trauma Knowledge Forum, the Subaxial Cervical AO Spine Injury Score was developed.

RESULTS

An A0 injury was assigned an injury score of 0, A1 a score of 1, and A2 a score of 2. Given the significant increase in severity, A3 was given a score of 4. Based on equal severity assessment, A4 and B1 were both assigned a score of 5. B2 and B3 injuries were assigned a score of 6. Unstable C-type injuries were given a score of 7. Stable F1 injuries were assigned a score of 2, with a 2-point increase for F2 injuries. Likewise, F3 injuries received a score of 5, whereas more unstable F4 injuries a score of 7. Neurologic status severity rating scores increased stepwise, with scores of 0 for N0, 1 for N1, and 2 for N2. Consistent with the Thoracolumbar AO Spine Injury Score, N3 (incomplete) and N4 (complete) injuries were given a score of 4. Finally, case-specific modifiers M1 (PLC injury) received a score of 1, while M2 (critical disc herniation) and M3 (spine stiffening disease) received a score of 4.

CONCLUSIONS

The Subaxial Cervical AO Spine Injury Score is an easy-to-use metric that can help develop a surgical algorithm to supplement the AO Spine Subaxial Cervical Spine Injury Classification System.

Cervical spine injuries requiring surgery in a Level I trauma centre in a major German city

BACKGROUND

Cervical spine injuries (CSI) are rare in trauma patients, at about 9.2-16.5/100,000 inhabitants in Scandinavia and Canada, and the annual incidence of CSI surgeries in Norway is around 3.0/100,000 inhabitants. However, despite their rarity, the incidence of CSI has increased, thereby assuming an increasing need for surgery. Outside of Scandinavia, no data about the incidence of CSI and subsequent surgeries exist. Therefore, this study aimed to analyse CSI epidemiology and surgery in a German city with a Level I trauma centre both to understand the injury and improve needs-based planning.

METHODS

This retrospective, monocentre study included all patients who presented with CSI from 2012-2017 at a university hospital with a Level I trauma centre in a major German city and had permanent residency within the city. Based on the assumption that the patients represented all CSI injuries in the city, as they were treated at the only available Level I trauma centre, the annual incidence of surgeries and neurologic deficits due to CSI were calculated.

RESULTS

A total of 465 patients with 609 CSI were identified. Of these patients, 61 both received surgery and resided in the city (mean age, 68.1 ± 18.3 years; 26 female, 35 male). The incidence of CSI surgeries was calculated as 3.24/100,000 person years (1.75/100,000 in the upper and 1.54/100,000 in the subaxial cervical spine). Neurologic deficits occurred in 0.64/100,000 person years. The incidence of both surgeries and neurologic deficits showed no significant changes over the 6-year study period.

CONCLUSIONS

Compared to Scandinavia, an increasing annual incidence for CSI surgeries and neurologic deficits were found. For long-term demand planning with adaptability to demographic changes, cross-regional studies including long-term follow-up are necessary.

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

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.

Subaxial Cervical Spine Injuries: WFNS Spine Committee Recommendations

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.