Early predictive value of supine and upright X-ray films of odontoid fractures treated with halo-vest immobilization

Background Although halo-vest immobilization remains a common form of treatment for type II odontoid fractures, nonunion and C1–2 instability may be the result in up to 20% to 40% of patients. Purpose Supine and upright lateral X-ray films may allow early identification of patients likely to fail halo-vest treatment and earlier surgical treatment with decreased morbidity from prolonged unsuccessful halo-vest immobilization. Study design/setting A prospective cohort study was performed. Patient sample Twenty patients with type II odontoid fractures. Outcome measures Posttreatment nonunion and C1–2 instability as determined by plain X-ray films and computed tomography scan. Methods Both supine and upright lateral X-ray films were obtained immediately after halo-vest application and at the 2-week, 6-week, and 3-month follow-up. Flexion-extension lateral X-ray films were obtained after halo-vest removal. Patients with nonunion or instability underwent computed tomography scan. Upright X-ray films were compared serially to identify loss of reduction. Pairs of supine and upright X-ray films were compared to measure any change in displacement or angulation upon transition from supine to upright position. Nonunion patients were compared with healed patients to determine any difference in fracture behavior based on serial supine and upright X-ray films. Results Twenty patients with type II odontoid fractures were identified during the study period. Three patients with multiple trauma underwent immediate surgical stabilization. Three elderly patients with nondisplaced fractures were treated in a cervical orthosis. Fourteen patients initiated and completed 3 months of halo-vest immobilization. After halo-vest removal, 4 of 14 patients (29%) showed radiographic nonunion or instability. In all 4 nonunion patients, supine and upright radiographs at 2 weeks revealed change in fracture angulation ≥5° between the supine and upright positions. In three of these patients standard serial upright lateral X-ray films failed to identify any loss of reduction. In the remaining patient, progressive angulation of 15° was observed. No measurable change in angulation between supine and upright X-ray films was observed in any patient who healed successfully with halo-vest treatment. Conclusions Obtaining both supine and upright lateral X-ray films during the follow-up period may identify patients at risk for failure of halo-vest treatment as early as 2 weeks after initiation of treatment. A change in fracture angulation ≥5° suggests an increased risk of treatment failure and the potential benefit of early surgical stabilization.