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