Correlation of C2 fractures and vertebral artery injury.

STUDY DESIGN Retrospective review of prospectively collected data. SUMMARY OF BACKGROUND DATA Vertebral artery injuries (VAI) occur commonly after cervical spine trauma. No study has yet examined the association between VAI and specific variants of C2 fractures. OBJECTIVE To evaluate the incidence of VAI (as defined by magnetic resonance imaging/angiography [MRI/A]) in subtypes of C2 fractures. To define the association between the incidence, morphology, and severity of C2 fractures, based on fracture angulation and comminution, and the occurrence of VAI. METHODS Patients admitted to the hospital with C2 fractures between October 2006 and December 2008 to a tertiary care referral center were identified through a prospectively maintained database. Computed tomography (CT) and MRI/A studies were individually reviewed to evaluate the specific C2 fracture type and the occurrence of VAI. Fracture displacement and angulation were measured. Incidence of VAI was compared between different types and subtypes of C2 fractures. The effects of displacement and angulation of the fracture, morphology of foramen transversarium fracture, patient age, and patient gender on VAI were also analyzed. RESULTS One hundred one patients were identified with C2 fractures that met inclusion criteria, and 18 (17.8%) had VAI by MRI/A. There was no correlation between fracture types and VAI. However, in subtype analysis, there was a correlation of VAI with traumatic spondylolisthesis of axis (TSA) and greater degree of angulation (P = 0.0023), communition fracture (P = 0.0341), and presence of bone fragment(s) within the foramen transversarium (P = 0.0075). Multivariate logistic regression indicated that age, gender and the presence of fragments within foramen transversarium were associated with greater risk of VAI. CONCLUSION Vertebral artery injuries are more likely to occur in C2 fractures with comminuted fractures involving the foramen transversarium, with fractures manifesting bony fragment(s) within the foramen transversarium, or with fractures having greater angulation. These risk factors should be considered when a patient presents with isolated axis fracture.