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Accuracy and reliability of the AO Spine subaxial cervical spine classification system grading subaxial cervical facet injury morphology

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Abstract

Purpose

A classification system was recently developed by the international association AO Spine for assessing subaxial cervical spine fractures. Significant variability exists between users of the facet component, which consists of four morphological types (F1–F4). The primary aims of this study were to assess the diagnostic accuracy and reliability of this new system’s facet injury morphological classifications.

Methods

A survey consisting of 16 computed tomography (CT) scans of patients with cervical facet fractures was distributed to spine surgeon members of AO Spine Latin America. To provide a gold standard diagnosis for comparison, all 16 injuries had been classified previously by six co-authors and only were included after total consensus was achieved. Demographic and surgical practice characteristics of all respondents were analyzed, and diagnostic accuracy calculated. Inter- and intra-observer agreement rates were calculated across two survey rounds, conducted one month apart.

Results

A total of 135 surgeons completed both surveys, among whom the mean age was 41.6 years (range 26–71), 130 (96.3%) were men, and 83 (61.5%) were orthopedic surgeons. The mean time in practice as a spine surgeon was 9.7 years (1–30). The overall diagnostic accuracy of all responses was 65.4%. Inter-observer and intra-observer agreement rates for F1/F2/F3/F4 were 55.4%/47.6%/64.0%/94.7% and 60.0%/49.1%/58.0%/93.0%, respectively.

Conclusion

This study evaluates the AO Spine Classification System specifically for facet injuries involving the subaxial cervical spine in a large sample of spine surgeons. There was significant variability in diagnostic accuracy for F1 through F3-type fractures, whereas almost universal agreement was achieved for F4-type injuries.

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Acknowledgements

This study was organized by the AO Spine Latin America Trauma Study Group. AO Spine is a clinical division of the AO Foundation, which is an independent medically-guided not-for-profit organization. Study support was provided directly through AO Spine Latin America regarding data collection, data analysis and proofreading.

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Authors and Affiliations

  1. Department of Neurosurgery, Hospital Clínico Regional de Concepción, San Martín 1436, Concepción, Chile

    Juan P. Cabrera

  2. Faculty of Medicine, University of Concepción, Concepción, Chile

    Juan P. Cabrera

  3. Department of Orthopedic and Traumatology, Department of Traumatology, University del Desarrollo (UDD). Spine Unit, Clínica Alemana, Santiago, Chile

    Ratko Yurac & Juan J. Zamorano

  4. Spine Unit, Orthopedic Department, Hospital Español de Mendoza, Mendoza, Argentina

    Alfredo Guiroy

  5. Department of Neurosurgery, University of Campinas (UNICAMP), Campinas, São Paulo, Brazil

    Andrei F. Joaquim

  6. Department of Neurosurgery, University of Passo Fundo, São Vicente de Paulo Hospital, Passo Fundo, Rio Grande do Sul, Brazil

    Charles A. Carazzo

  7. ScienceRight Research Consulting, London, ON, Canada

    Kevin P. White

  8. Department of Orthopedic and Traumatology, Hospital Churruca Visca, Buenos Aires, Argentina

    Marcelo Valacco

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  1. Juan P. Cabrera
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and the AO Spine Latin America Trauma Study Group

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Cabrera, J.P., Yurac, R., Guiroy, A. et al. Accuracy and reliability of the AO Spine subaxial cervical spine classification system grading subaxial cervical facet injury morphology. Eur Spine J 30, 1607–1614 (2021). https://doi.org/10.1007/s00586-021-06837-w

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  • DOI: https://doi.org/10.1007/s00586-021-06837-w

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