Surgical technique of 3D computer-assisted navigated posterior fixation of the upper cervical spine: illustration of three cases.

Instrumentation of the upper cervical spine, such as cervical pedicle, lateral mass, pars, or translaminar screws, is considered high risk due to the specific challenges of this anatomic region, including the proximity of vertebral and carotid arteries and nerve roots, as well as its delicate bony architecture. In recent years, advanced three-dimensional (3D) imaging techniques, such as intraoperative computed tomography (iCT; AIRO CT), have emerged, enabling computer-assisted navigation (CAN). This integration of real-time imaging into navigation enhances screw accuracy and diminishes perioperative risks, extending to the postsurgical confirmation of screw placement. Although CAN utilization has become more prominent in lumbar and thoracic surgeries, its integration into cervical spine procedures has been constrained thus far. This can be ascribed to the variable screw trajectories necessary for cervical spine procedures, coupled with potential anatomical variations such as a high-riding vertebral artery, increasing the degree of challenge during surgery. To date, no study has comprehensively described in detail the technique of upper cervical instrumentation employing automatic image registration, navigation, and iCT validation of the positioned screws. In this manuscript, a detailed description of CAN in high cervical instrumentation is given, including C1 lateral mass screws with the notching technique, C2 and C3 pars screws, and translaminar screws guided by preoperative magnetic resonance imaging (MRI) data and iCT for assessment of screw position. For this purpose, three different patients suffering from distinct cervical pathologies, such as nonunion of a C2 fracture and atlantoaxial arthropathy with or without ankylosis, are presented, with a specific surgical approach tailored to the anatomical variations of each patient.