McMaster University

McMaster University

Atlantoaxial instability in acute odontoid fractures

MacOrtho is pleased to announce the most recent publication in the Spine journal. This publication is entitled “Atlantoaxial instability in acute odontoid fractures is associated with nonunion and mortality."

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Evaniew N, Yarascavitch B, Madden K, Ghert M, Drew B, Bhandari M, Kwok D. Atlantoaxial instability in acute odontoid fractures is associated with nonunion and mortality. Spine J. 2014 Mar 21. pii: S1529-9430(14)00303-9. doi: 10.1016/j.spinee.2014.03.029. [Epub ahead of print]


BACKGROUND CONTEXT: Odontoid fractures are the most common geriatric cervical spine fractures. Non-union rates have been reported to be up to 40%, mortality up to 35%, and poor functional outcomes are common. Atlantoaxial instability (AAI) is a plausible prognostic factor, but its role has not been previously examined.

PURPOSE: To determine the effect of severe AAI on the outcomes of non-union and mortality in patients with acute odontoid fractures.

STUDY DESIGN/SETTING: Retrospective Cohort/Single-Institution PATIENT SAMPLE: One hundred and twenty-four consecutive patients with acute odontoid fractures.

OUTCOME MEASURES: Rates of non-union and mortality.

METHODS: Two independent blinded reviewers measured AAI using post-injury CT scans. Patients were classified as having "severe" or "minimal" AAI on the basis of greater versus less than or equal to 50% mean subluxation across each C1-C2 facet joint. Rates of non-union and mortality were compared using independent samples t-tests and adjusted for age, displacement, and subtype using binary logistic regression. This study received funding from the Hamilton Health Sciences Spine Program and Dr. Bhandari is funded in part by a Canada Research Chair. The authors do not declare any conflicts of interest.

RESULTS: One hundred and seven patients had minimal AAI, and 17 had severe AAI. Mean follow-up was 4.4 months (SD=4.6). Patients with severe AAI were more likely to experience non-union (29% vs 10%, respectively; p=0.03) and mortality (35% vs 14%, respectively; p=0.03) regardless of treatment modality. Fracture displacement correlated with AAI (r2 = 0.65). When adjusted for patient age, the odds ratio of non-union with severe AAI approached significance at 3.3 (95% CI: 0.9 - 11.7). Mortality prediction with AAI approached a two-fold increased risk (odds ratio = 2.1; 95% CI: 0.6 - 6.8). In patients with type-II fractures, the odds of mortality with severe AAI approached a threefold higher risk (odds ratio = 3.3; 95% CI: 0.9 - 12.3).

CONCLUSIONS: Patients with acute odontoid fractures and severe AAI may be more likely to experience non-union and mortality, suggesting the possibility that aggressive management could be warranted. Further investigation with a large prospective study including patient-important functional outcomes is justified.

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