Unilateral Cervical Spine Facet Fractures: Radiographic Predictors of Instability

Retrospective cohort study.

The purpose of our study is to identify CT characteristics of unilateral cervical spine facet fractures that are predictive of instability on MRI.

Management of isolated subaxial cervical spine facet fractures is typically based on the neurological status of the patient and perceived stability of the injury. It has been shown that the degree of ligamentous instability can help predict instability and need for surgery, and MRIs are increasingly being used to evaluate these injuries, but not always. While there are studies that evaluate radiographic characteristics of facet fractures on CT, there are few that specify which CT findings predict instability on MRI.

A retrospective review of 49 patients with unilateral cervical facet fractures during a 7-year period from a level I trauma center was performed. All patients had a CT and an MRI performed. Measurements of fracture fragments were obtained from CT scans. MRIs were examined by an independent radiologist and assigned an instability score. CT measurements were compared with MRI instability scores to determine which parameters were predictive of the need for operative stabilization.

Forty-nine patients were identified with unilateral cervical spine facet fractures. Thirty patients initially were treated nonoperatively, and 19 patients underwent surgical stabilization. One patient failed nonoperative management, having neurological deficits and pain at follow-up, and underwent a C6-C7 ACDF later. The average instability score in the operative group was 3.34, versus 1.06 in the conservative treatment group ( P <0.001). Fracture displacement ( P =0.013), multifragmentary fractures ( P <0.001) and MRI instability score ( P <0.001) were correlated with a statistically significant increased likelihood of operative necessity.

Fracture size did not directly correlate with ligamentous injury. Displacement and multifragmentary fractures on CT scan were had the highest correlation with instability scores on MRI. This suggests that patients with subaxial cervical facet fractures that are comminuted or have significant displacement may require operative stabilization.

Level III.