Fluoroscopic Detection of Ventral Wall Violation during C2 Intralaminar Screw Insertion: A Descriptive Study

Abstract

Introduction: The C2 (second cervical) laminar screws were considered for rigid fixation of the axis because the use of pars or pedicle screws posed a risk to the vertebral artery with C2. Though considered to be a relatively safe method, ventral spinal canal violations have been reported in laminar screws fixations. Fluoroscopy-based image guidance may increase the accuracy and safety of the technique. Aim: To report the use of fluoroscopy technique in the detection of ventral wall violation during C2 intralaminar screw insertion. Materials and Methods: This descriptive study reports seven dry axis vertebrae from the adult south Indian population for which fluoroscopic analysis was done from January 2013 to December 2013. True lateral views were taken before and after applying a vertical line of barium paint on the ventral surface of the lamina at two points: at the centre of the lamina and close to the facet joints at the face to-laminar junction. Results: In the total seven dry axis vertebrae analysed, the mean ratio of the distance from the spinolaminar junction to the barium line (drawn on the ventral surface of the lamina just next to face to laminar junction) to the distance between the spinolaminar junction and uppermost part of inferior articular facet of C2 vertebrae was 0.465±0.0389 mm. Conclusion: Even though considered a relatively safer technique, laminar cortical violations have been reported in C2 translaminar screw fixations. Fluoroscopy-based imaging guidance can improve the accuracy of C2 translaminar screw insertion, as this technology provides real-time imaging during the process of screw insertion and helps in accurate screw sizing.

Keywords

• anatomy
• computer-assisted
• isocentre c-arm
• navigation
• translaminar screw
• vertebra