AOSpine subaxial cervical spine injury classification system

FLM fractures of the subaxial cervical spine involves separation of the lateral mass from the vertebrae via a disruption of both the lamina and pedicle, resulting in a disconnection of the superior and inferior articular processes. This subset of cervical spine fractures is highly unstable, making proper treatment selection of great importance.

Methods: In this single-center, retrospective study, we identified patients meeting the definition of an FLM fracture. Radiological imaging from the date of injury was reviewed to ensure presence this injury pattern. Treatment course was assessed to determine nonoperative versus operative treatment. Operative treatment was divided into patients who underwent anterior, posterior, or combined anterior-posterior spinal fusion. We then reviewed postoperative complications among each of the subgroups.

Results: Forty-five patients were determined to have a FLM fracture over a 10-year span. The nonoperative group had n=25, and evidently, there were no patients that crossed over to surgery due to subluxation of the cervical spine after nonoperative treatment. The operative treatment group had n=20, and consisted of 6 anterior, 12 posterior, and 2 combined approaches. Complications appeared in posterior and combined groups. Two hardware failures were noted in the posterior group, along with two postoperative respiratory complications in the combined group. No complications were observed for the anterior group.

Conclusions: None of the nonoperative patients in this study required further operation or management of their injury, indicating nonoperative treatment as a potentially satisfactory management for appropriately selected FLM fractures ¹⁾