Management of Nondisplaced Type II Odontoid Fractures in Elderly Patients: A Comparison of Military and Civilian Populations

Study Design: Retrospective cohort study. Objective: The purpose of this study is to investigate patterns of surgical treatment of nondisplaced type II odontoid fractures. Summary of Background Data: Odontoid fractures represent ∼1/3 of all cervical spine fractures, resulting from low-energy mechanisms in the elderly. Type I and III odontoid fractures are typically treated nonoperatively with Aspen collar immobilization. Treatment of type II odontoid process fractures is of particular interest because of the risk of nonunion, secondary to the watershed blood supply to the base of the odontoid process. Though there is consistent agreement regarding the management of displaced type II fractures, there is marked heterogeneity in the clinical management of nondisplaced type II fractures. Methods: We queried the Military Health System Data Repository for the ICD-10 codes for nondisplaced type II odontoid fractures and CPT codes for surgical treatment, from 2015 to 2022. We excluded patients under the age of 65, polytraumatized patients, and patients with a diagnosis of displaced type II odontoid fracture during any clinical encounter. Results: Four hundred two patients were diagnosed with nondisplaced type II odontoid fractures. 90.3% of patients underwent nonoperative management. Of the 39 patients (9.70%) undergoing surgery, 56% underwent C1-C2 arthrodesis and 44% underwent anterior odontoid screw fixation. There was no significant difference between surgical rates in the military and nonmilitary population (P=0.46). No patient with an initially diagnosed nondisplaced fracture experienced late displacement. The nonunion prevalence was 3.2% and only occurred in patients managed nonoperatively. No patient with an isolated type II odontoid fracture nonunion underwent surgery. Conclusions: Nonoperative management of nondisplaced type II odontoid fractures is the preferred treatment modality in this cohort. C1-C2 fusion remains the most common surgical treatment modality. There is no evidence that late displacement is common or expected in patients undergoing nonoperative management. No patient with a diagnosed fracture nonunion underwent delayed surgical intervention.