An independent inter- and intra-observer agreement assessment of the AOSpine upper cervical injury classification system

Published:November 14, 2022DOI:



      The complex anatomy of the upper cervical spine resulted in numerous separate classification systems of upper cervical spine trauma. The AOSpine upper cervical classification system (UCCS) was recently described; however, an independent agreement assessment has not been performed.


      To perform an independent evaluation of the AOSpine UCCS.


      Agreement study.


      Eighty four patients with upper cervical spine injuries.


      Inter-observer agreement; intra-observer agreement.


      Complete imaging studies of 84 patients with upper cervical spine injuries, including all morphological types of injuries defined by the AOSpine UCCS were selected and classified by six evaluators (from three different countries). The 84 cases were presented to the same raters randomly after a 4-week interval for repeat evaluation. The Kappa coefficient (κ) was used to determine inter- and intra-observer agreement.


      The interobserver agreement was almost perfect when considering the fracture site (I, II or III), with κ=0.82 (0.78–0.83), but the agreement according to the site and type level was moderate, κ=0.57 (0.55–0.65). The intra-observer agreement was almost perfect considering the injury, with κ=0.83 (0.78–0.86), while according to site and type was substantial, κ=0.69 (0.67–0.71).


      We observed only a moderate inter-observer agreement using this classification. We believe our results can be explained because this classification attempted to organize many different injury types into a single scheme.


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        • Anderson PA
        • Montesano PX.
        Morphology and treatment of occipital condyle fractures.
        Spine (Phila Pa 1976). 1988; 13: 731-736
        • Levine AM
        • Edwards CC.
        Fractures of the atlas.
        J Bone Joint Surg Am. 1991; 73: 680-691
        • Anderson LD
        • D'Alonzo RT.
        Fractures of the odontoid process of the axis.
        J Bone Joint Surg Am. 1974; 56: 1663-1674
        • Levine AM
        • Edwards CC.
        The management of traumatic spondylolisthesis of the axis.
        J Bone Joint Surg Am. 1985; 67: 217-226
        • Shafafy R
        • Valsamis EM
        • Luck J
        • Dimock R
        • Rampersad S
        • Kieffer W
        • et al.
        Predictors of mortality in the elderly patient with a fracture of the odontoid process.
        Bone Joint J. 2019; 101-B: 253-259
        • Effendi B
        • Roy D
        • Cornish B
        • Dussault RG
        • Laurin CA.
        Fractures of the ring of the axis. A classification based on the analysis of 131 cases.
        J Bone Joint Surg Br. 1981; 63-B: 319-327
        • Traynelis VC
        • Marano GD
        • Dunker RO
        • Kaufman HH.
        Traumatic atlanto-occipital dislocation. Case report.
        J Neurosurg. 1986; 65: 863-870
        • Vaccaro AR
        • Karamian BA
        • Levy HA
        • Canseco Jose
        • Rajasekaran Shanmuganathan
        • Benneker Lorin
        • et al.
        Update on upper cervical injury classifications: the new AO upper cervical spine classification system.
        Clin Spine Surg. 2022; 35: 249-255
        • Maeda FL
        • Formentin C
        • de Andrade EJ
        • Sousa Pedro
        • Goyal Dhruv
        • Shroeder Gregory
        • et al.
        Reliability of the New AOSpine classification system for upper cervical traumatic injuries.
        Neurosurgery. 2020; 86: E263-EE70
      1. AOSpine. AOSpine upper cervical classification system. Available at: www.youtubecom/watch?v=KyUYfa_JMb4. 2018. Accessed July 20, 2022.

        • Vaccaro AR
        • Lambrechts MJ
        • Karamian BA
        • Canseco Jose
        • Oner Cumhur
        • Vialle Emiliano
        • et al.
        AO spine upper cervical injury classification system: a description and reliability study.
        Spine J. 2022; (In press)
        • Rotondi MA
        • Donner A.
        A confidence interval approach to sample size estimation for interobserver agreement studies with multiple raters and outcomes.
        J Clin Epidemiol. 2012; 65: 778-784
        • Landis JR
        • Koch GG.
        The measurement of observer agreement for categorical data.
        Biometrics. 1977; 33: 159-174
        • Urrutia J
        • Zamora T
        • Campos M
        • Yurac Ratko
        • Palma Joaquin
        • Mobarec Sebastian
        • et al.
        A comparative agreement evaluation of two subaxial cervical spine injury classification systems: the AOSpine and the Allen and Ferguson schemes.
        Eur Spine J. 2016; 25: 2185-2192
        • Audige L
        • Bhandari M
        • Hanson B
        • Kellam J
        A concept for the validation of fracture classifications.
        J Orthop Trauma. 2005; 19: 401-406
        • Urrutia J
        • Zamora T
        • Yurac R
        • Campos M
        • Palma J
        • Mobarec S
        • et al.
        An independent interobserver reliability and intraobserver reproducibility evaluation of the new AOSpine Thoracolumbar Spine Injury Classification System.
        Spine. 2015; 40 (Phila Pa 1976): E54-E58
        • Urrutia J
        • Zamora T
        • Yurac R
        • Campos M
        • Palma J
        • Mobarec S
        • et al.
        An independent inter- and intraobserver agreement evaluation of the AOSpine subaxial cervical spine injury classification system.
        Spine. 2017; 42 (Phila Pa 1976): 298-303
        • Urrutia J
        • Meissner-Haecker A
        • Astur N
        • Valencia M
        • Yurac R
        • Camino-Willhuber G
        • et al.
        An independent inter- and intraobserver agreement assessment of the AOSpine sacral fracture classification system.
        Spine J. 2021; 21: 1143-1148
        • Karamian BA
        • Schroeder GD
        • Levy HA
        • Canseco Jose
        • Benneker Lorin
        • Kandziora Frank
        • et al.
        The Influence of Surgeon Experience and Subspeciality on the Reliability of the AO Spine Sacral Classification System.
        Spine (Phila Pa 1976). 2021; 46: 1705-1713