AOSpine subaxial cervical spine injury classification system



This project describes a morphology-based subaxial cervical spine traumatic injury classification system. Using the same approach as the thoracolumbar system, the goal was to develop a comprehensive yet simple classification system with high intra- and interobserver reliability to be used for clinical and research purposes.


A subaxial cervical spine injury classification system was developed using a consensus process among clinical experts. All investigators were required to successfully grade 10 cases to demonstrate comprehension of the system before grading 30 additional cases on two occasions, 1 month apart. Kappa coefficients (κ) were calculated for intraobserver and interobserver reliability.


The classification system is based on three injury morphology types similar to the TL system: compression injuries (A), tension band injuries (B), and translational injuries (C), with additional descriptions for facet injuries, as well as patient-specific modifiers and neurologic status. Intraobserver and interobserver reliability was substantial for all injury subtypes (κ = 0.75 and 0.64, respectively).


The AOSpine subaxial cervical spine injury classification system demonstrated substantial reliability in this initial assessment, and could be a valuable tool for communication, patient care and for research purposes.

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AOSpine is a clinical division of the AO Foundation—an independent medically guided not for profit organization. The AO has a strong financial independence thanks to the foundations endowment. The annual operating activities are financed through three pillars: Collaboration and support agreements with DePuy Synthes and other industrial partners, return on own financial assets and other third party income (e.g., participant fees, R&D projects, memberships). The AOSpine Knowledge Forums are pathology focused working groups acting on behalf of AOSpine in their domain of scientific expertise. Each forum consists of a steering committee of up to 10 international spine experts who meet biannually to discuss research, assess the best evidence for current practices, and formulate clinical trials to advance their field of spine expertise. Authors are compensated for their travel and accommodation costs. Study support is provided directly through AOSpine’s Research department and AO’s Clinical Investigation and Documentation unit. There are no other institutional subsidies, corporate affiliations or funding sources supporting this work unless clearly documented and disclosed.

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Correspondence to Alexander R. Vaccaro.

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Vaccaro, A.R., Koerner, J.D., Radcliff, K.E. et al. AOSpine subaxial cervical spine injury classification system. Eur Spine J 25, 2173–2184 (2016).

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  • AOSpine
  • Subaxial
  • Cervical
  • Spine
  • Trauma
  • Injury
  • Classification