Accuracy of atlantoaxial screw placement using computed tomography-based navigation system-assisted surgery: The single-level vertebral registration

• Published in: Interdisciplinary neurosurgery : Advanced techniques and case management Vol. 32; p. 101740
• Main Authors: Oearsakul, Thakul, Tunthanathip, Thara, Kaewborisutsakul, Anukoon
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-06-2023; Elsevier
• Subjects: Atlantoaxial; C1 lateral mass; C2 pedicle; Navigation system; Pedicle screws; C2 pedicle; C1LM; Navigation system; HRVA; Pedicle screws; C1 lateral mass; C2PS; Atlantoaxial
• ISSN: 2214-7519; 2214-7519
• DOI: 10.1016/j.inat.2023.101740

•Posterior approach fixation is commonly used to treat atlantoaxial instability.•C1 and C2 posterior screw fixation faces anatomy and motion (fracture) challenges.•CT-based navigation systems help the surgeon place the instrumentation fixation.•Single-level registration was successful when navigation systems were used.•Small size of C1 lateral mass and of C2 pedicles demands attention in navigation.
Posterior screw fixation via a C1 lateral mass screw combined with a C2 pedicle screw is a well-known technique for atlantoaxial instability. However, screw malposition can occur because of the complex anatomical structure of this region. This study aimed to evaluate the accuracy and risk factors of cortical breach following the C1 lateral mass and/or C2 pedicle screw insertion using a preoperative computed tomography (CT)-based navigation system with a single-level vertebral registration method.
This retrospective cohort study included patients who had undergone a C1 lateral mass and/or a C2 pedicle screw placement using a preoperative CT-based navigation system from January 2013 to March 2020 from the university hospital. The extent of screw deviation was classified as: within the pedicle (grade 0), out of pedicle < 2 mm (grade I), from 2 to 4 mm (grade II), and > 4 mm (grade III). The risk of cortical breach was evaluated using multivariate analysis.
Seventy-eight C1 lateral masses and 71 C2 pedicle screws were inserted into 42 patients. The accuracy of screw placement was as follows: 133 grade 0 (89.3 %), 14 grade I (9.4 %), and two grade II (1.3 %). No screws required repositioning, and no vertebral artery injury or neurological deficit was associated with this technique. Additionally, a diameter of < 5 mm was associated with the cortical breach in the multivariate analysis.
C1 lateral mass and C2 pedicle screw placement could be safely and effectively performed by using a preoperative CT-based navigation system with a single-level registration technique. The risk factors for cortical breach are the C1 lateral mass and C2 pedicle diameters.