Navigated Atlas Osteosynthesis for Unstable Jefferson Fractures

Introduction: Jefferson burst fractures of the atlas are typically considered “stable” or “unstable” based upon integrity of the transverse ligament. Whereas stable Jefferson fractures can be treated non-operatively, unstable fractures with mid-substance rupture (Dickman Type I) or bony avulsion (Dickman Type II) of the transverse ligament often require surgical intervention. Atlas osteosynthesis has been proposed as a motion-preserving alternative to atlantoaxial fusion.

Methods: Cases of unstable Jefferson fractures treated with atlas osteosynthesis at a single Level I Trauma Center were identified and retrospectively reviewed. Clinical and radiographic presentation, surgical management and post-operative outcomes were assessed.

Results: Six patients (5 males, 1 female; median age 49.5 years, range 24-61 years) underwent atlas osteosynthesis for unstable Jefferson fractures between 2015 and 2023. All cases demonstrated injury to the transverse ligament (Dickman Type I (n=1), Type II (n=4), and mixed Type I/II (n=1)). Bilateral C1 lateral mass screws were placed with assistance of intraoperative CT guided navigation. Screws were connected to each other using a single 3.5mm rod and fractures reduced. Patients were maintained in a rigid cervical collar following surgery (median duration 12 weeks, range 6-60 weeks). All six patients were followed with serial upright radiographs demonstrating preserved alignment. Five patients obtained outpatient follow-up CT, all of which demonstrated evidence of osseous union across fractures without hardware complication. None developed post-operative occipital-cervical or atlantoaxial instability requiring additional fusion. Median follow-up 11.5 months (range 2-91 months).

Conclusion : Atlas osteosynthesis is an attractive motion-preserving surgical approach to the treatment of unstable Jefferson fractures, avoiding the morbidity of atlantoaxial fusion. Intraoperative navigation can be particularly useful for screw placement in the setting of traumatically distorted anatomy with lateral mass displacement. Classically reserved for Jefferson fractures with Dickman Type II transverse ligament injury, atlas osteosynthesis may also be a viable option for Type I transverse ligament injuries.