Predictors of Vertebral Artery Injury in Isolated C2 Fractures Based on Fracture Morphology Using CT Angiography

Study Design. Retrospective database analysis. Objective. To determine C2 fracture patterns associated with vertebral artery injury (VAI) as assessed by computed tomography angiography. Summary of Background Data. The incidence of C2 fracture hospitalizations has increased significantly in the last decade. The vertebral arteries are susceptible to injury as each courses through the C2 transverse foramen. Early screening for VAI to institute antithrombotic treatment is critical to prevent ischemic neurological sequelae. Imaging-based fracture classification schemes to determine which patterns are predictors of VAI in isolated C2 fractures using computed tomography angiography have not been described. Methods. Cervical spine computed tomographic (CT) scans at a level I trauma center were reviewed for isolated C2 fractures from 2004 to 2014 under institutional board review approval. Exclusion criteria included penetrating injury or additional cervical/occipital fractures. Fractures were classified using multiplanar CT scans into type I/II/IIa/III spondylolisthesis, type I/IIA/IIB/IIC/III dens, transverse foramen (displacement/comminution/intraforaminal fragments), and miscellaneous vertebral body fractures. Corresponding CT angiograms were assessed for VAI on the basis of the Denver grading criteria. Fisher exact test and Student t test were performed to determine predictors of VAI on the basis of fracture type. Results. Sixty-seven patients met inclusion criteria. Fracture pattern analysis revealed that the majority were dens fractures (50.8%) and traumatic spondylolisthesis (41.8%); 29.9% had miscellaneous coronal/sagittal fractures and 22.4% were a combination. VAI was identified in 37.3% of patients with isolated C2 fractures, and 88% of patients had transverse foramen involvement. Fracture patterns significantly associated with VAI were type III dens and transverse foramen fractures with intraforaminal fragments, with or without comminution. Conclusion. The C2 fracture pattern most associated with VAI was comminuted transverse foramen fracture with intraforaminal fragments. Transverse foramen fracture alone was not found to be significant. These results help stratify patients with isolated C2 fractures who are at high VAI risk and should be further evaluated with computed tomography angiography.