Management of combined atlas and axis fractures: a systematic review

BACKGROUND: Combined atlas-axis fractures are rare occurrences with substantially higher rates of neurologic deficits compared with isolated injuries. Given the intricate anatomic relationship between the atlas and axis vertebra, variable fracture patterns may occur, warranting special considerations from surgeons. METHODS: A systematic search of PubMed and EMBASE was performed following the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Relevant studies on acute combined atlas-axis fractures that provided data on patient demographics, presentation (injury mechanism, neurologic deficits, fracture type), management, complications, and study conclusions were reviewed. RESULTS: A total of 22 articles published from 1977 to 2022, comprising 230 patients, were included in the final analysis. Thirty-seven of the 213 patients (17%) presented with neurologic deficits. The most common atlas injuries were posterior arch fractures (54/169 patients; 32%), combined posterior arch/anterior arch fractures (44/169 patients; 26%), and anterior arch fractures (43/169 patients; 25%). The most common axis injuries were type II odontoid fractures (115/175 patients; 66%). Of the 127 patients managed operatively (127/230 patients; 55%), 45 patients (35%) were treated with C1-C2 posterior spinal fusion, 33 patients (26%) were treated with odontoid screw fixation and anterior/posterior C1-C2 trans-articular screws, 16 patients (13%) were treated with occiputocervical fusion and 12 patients (9%) were treated with odontoid screw fixation alone. CONCLUSIONS: Management strategies are generally based on the type of axis fracture as well as the condition of the transverse ligament. Patients with stable fractures can be successfully managed nonoperatively with a cervical collar or halo immobilization. Combined atlas-axis fractures with an atlantodental interval >5 mm, C1 lateral mass displacement >7 mm, C2-C3 angulation >11° or an MRI demonstrating a disrupted transverse ligament are suggestive of instability and are often successfully managed with surgical intervention. There is no consensus regarding surgical technique.