Posterior atlantoaxial stabilization: a new alternative to C1–C2 transarticular screws

Abstract

Purpose of study: Develop new techniques to improve safety and success of C1–C2 fusion procedures.Methods used: A standard posterior C1–C2 exposure is performed. Cross-table lateral fluoroscopy is used to guide and confirm screw trajectories. The C2 pedicle screw entry point is identified and drilled with angles 15 degrees medially and 25 degrees cephalad for pedicle cannulation. Drill depth is stopped short of the C2 transverse foramen. The C1 lateral mass screw insertion point is located beneath the posterior arch of C1 in the midposition of the lateral mass just above the C2 root. The drill is then angled 10 degrees medial to lateral and cephalad toward the anterior tubercle of C1 on lateral fluoroscopy. The C1–C2 joint is then decorticated and packed with local bone fragments. Posterior rods are contoured and connected to polyaxial screw heads, and a cross-connector is applied.of findings: This technique has been used in five cases of atlantoaxial instability at our institution during the past year. There have been no C2 nerve root or vertebral artery injuries. No construct failures have been observed during the current follow-up.Relationship between findings and existing knowledge: C1 lateral mass and C2 pedicle screw fixation offers an alternative means of atlantoaxial fusion. The technique is less demanding than C1–C2 transarticular screw placement and reduces the risk of vertebral artery injury. The linked construct is stable in flexion, extension and rotation. Laminectomy or fracture of the posterior elements does not preclude this fixation technique. We think this procedure will replace the C1–C2 transarticular screw procedure.Overall significance of findings: This new technology has the potential to supplant previous C1–C2 procedures with improved safety and success.Disclosures: Device or drug: pedicle screws. Status: approved.Conflict of interest: No conflicts.