Spine - 2026-08-24 - Journal Article
A Surgical Algorithm for Upper Cervical Trauma Based on the AO Spine Upper Cervical Injury Classification System.
Vaccaro AR, Ng MK, Dalton J, Schnake K, Bransford R, Chhabra HS, El-Sharkawi M, Bigdon S, Joaquim A, Schroeder GD
Topics
Key Takeaway
A 159-surgeon international survey established UC-AOSIS operative thresholds: scores ≤3 favor nonoperative management, scores ≥5 favor surgery, and score 4 represents an equipoise zone without consensus.
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Summary
This study sought to define operative versus nonoperative thresholds for upper cervical spine injuries using the AO Spine Upper Cervical Injury Classification (UCIC) system by surveying 159 international orthopaedic and neurosurgery spine surgeons via clinical vignettes spanning UCIC subtypes A3, B1, B2, B3, and C1 modified by neurological grade and case modifiers. Using a 70% agreement consensus threshold per AO Spine Knowledge Forum Trauma methodology, the resulting UC-AOSIS framework identified scores ≤3 as consistently nonoperative and scores ≥5 as consistently operative across regions and subspecialties. High-morphology-severity patterns (B3, C1), unstable B2 subtypes, and neurologic impairment N2–N4 reliably crossed the operative threshold.
Key Limitation
The algorithm is derived entirely from surgeon preference data without any correlation to patient outcomes, functional recovery, or complication rates, leaving the clinical validity of the proposed thresholds unproven.
Original Abstract
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.