A Surgical Algorithm for Upper Cervical Trauma Based on the AO Spine Upper Cervical Injury Classification System.

STUDY DESIGN: Global cross-sectional survey. OBJECTIVE: To establish a surgical algorithm for upper cervical spine injuries using the AO Spine Upper Cervical Injury Classification (UCIC) system, defining operative thresholds using a novel proposed Upper Cervical AO-Spine Injury Score (UC-AOSIS). SUMMARY OF BACKGROUND DATA: The AO Spine UCIC system provides a hierarchical, morphology-based classification for upper cervical spine trauma. Although reliability has been previously demonstrated, there is no established consensus on operative versus nonoperative management for specific UCIC subtypes. METHODS: A survey including clinical vignettes of UCIC injury types (A3, B1, B2, B3, and C1), modified by neurological grades (N0-N4) and case-specific modifiers (M1-M5), was distributed to orthopaedic spine surgeons/neurosurgeons across AO Spine regions. Surgeons were asked whether a patient should undergo operative/nonoperative management for each scenario. Decision-making patterns were analyzed to identify severity thresholds, which were incorporated into a scoring framework. RESULTS: A total of 159 surgeons responded. An operative consensus threshold of 70% agreement was determined by AO Spine Knowledge Forum Trauma methodology, with consensus reached for most injury patterns. Across all regions and surgical subspecialties, fracture patterns with UC-AOSIS scores ≤3 were consistently managed nonoperatively, while those with scores ≥5 were treated operatively. Injuries given a score of 4 demonstrated variable surgeon preference, falling into an "equipoise" zone without strong consensus for either approach. CONCLUSION: The AO Spine Upper Cervical Classification System, combined with international multispecialty surgeon input, enabled creation of a novel surgical algorithm for upper cervical trauma (UC-AOSIS). High-severity morphology (B3, C1), unstable B2 subtypes, and any associated neurologic impairment (N2-N4) meet operative thresholds. LEVEL OF EVIDENCE: 4.