Fusion strategy after odontoid fracture and three-column atlantoaxial displacement in a patient with prior C2-pelvis fusion: a case report.

Background: Surgical intervention for scoliosis often involves extensive spinal fusions, at times spanning from the cervical spine to the pelvis. Proximal junctional failure is a known complication of C2-pelvis fusions, frequently presenting as fractures of the odontoid process. Managing these fractures is complex due to anatomical constraints and the need for structural stability while minimizing risks. This report presents a nuanced solution for a C2 fracture involving all three columns and C1 displacement in a patient with previous anterior C3-C6 and posterior C2-pelvis fusions. Case Description: A 66-year-old male with extensive spinal fusion history presented with bilateral hand paresthesia, global extremity weakness, and neck pain following a fall. Imaging revealed a comminuted type II odontoid fracture with C2 ventral body and right lateral mass involvement, along with significant spondylolisthesis of C2 secondary to ligamentous injury. Surgery was indicated due to spinal instability. Intraoperative reduction was followed by a new occiput-C7 posterior arthrodesis, including pedicle screws at C6 and C7 with a quad rod construct. C6 and C7 were not instrumented previously, or their instrumentation had been removed at some point during one of the several revisions that the patient underwent. The new rods were purposefully kept longer to connect the occipital plate to the C6 and C7 pedicle screws and then to the original C2-pelvis fusion at upper thoracic levels using side-to-side connectors. This conferred more stability to the new construct. Conclusions: This case highlights a surgical strategy for stabilizing complex cervical fractures in patients with previous extensive fusions and limited options for fixation while allowing minimal disruption of previous fusion masses and preexisting hardware. By extending the fusion to the occiput, using cervical pedicle screws, and integrating existing hardware, we achieved sound structural stability. This approach offers a potential fusion strategy for similar cases where preserving fusion integrity and spinal stability is critical amidst challenging anatomical constraints.