ABSTRACT
C1–C2 revision surgery is a technically demanding procedure, as normal anatomic landmarks are obscured, as well as the presence of vital organs: the transition from medulla oblongata to spinal cord and the vertebral artery, with its complex geometric anatomy. The indication for revision of C1–C2 fusion is nonunion with persistent or progressive symptoms, due to pseudarthrosis. The C1–C2 segment has the widest range of motion of any spinal motion segment, and this motion is increased significantly when there is pathological instability present. A patient's age and/or comorbidities may pose a relative contraindication as to what invasive technique can be used or whether an internal or external revision should be performed. Image guidance can be very helpful to guide screw placement in a revision situation due to distortion of the anatomy. Revision of atlantoaxial fusion is associated with an increased risk for intraoperative and postoperative complications due to the altered anatomy.
