Abstract / Summary
Objective: Posterior C1–C2 instrumentation is technically demanding because of the complex osseous and vascular anatomy of the atlantoaxial region. This retrospective single-center case series aimed to describe the technical feasibility and observed screw-placement outcomes of a combined microscope-integrated augmented reality (AR)-assisted navigation workflow in patients with atlantoaxial instability. Methods: Two neurosurgeons and one radiologist assessed screw placement accuracy on computed tomography (CT) images using the Gertzbein–Robbins classification, applying the Bredow modification for the cervical spine. Cortical breaches were classified as Grade 1, <1 mm; Grade 2, 1 to <2 mm; Grade 3, 2 to <3 mm; Grade 4, 3 to <4 mm; and Grade 5, ≥4 mm, or as transverse foramen obstruction exceeding half the screw diameter. Grades 1 and 2 were considered acceptable for screw insertion. Results: A total of 40 screws were successfully placed in 10 patients, comprising 20 C1 lateral mass screws and 20 C2 pedicle screws, achieving an overall acceptable placement rate of 97.5% (39/40; 95% CI, 86.8–99.9%). All 20 C1 lateral mass screws were accurately positioned, while the acceptable placement rate for C2 pedicle screws was 95.0%. One C2 pedicle screw in a 1.7 mm pedicle was graded as Grade 3. No clinically apparent vascular or neurological injuries were observed. Conclusions: The combined microscope-integrated AR-assisted navigation workflow was feasible in this small case series, with a high observed acceptable screw-placement rate and no observed neurovascular complications. The independent contribution of AR and its effects on outcomes relative to other guidance techniques require evaluation in larger comparative studies.