Coronal Multiplane Reconstructed Computed Tomography Image Determining Lateral Vertebral Notch-Referred Pedicle Screw Entry Point in Subaxial Cervical Spine: A Preclinical Study

Abstract

OBJECTIVE: To evaluate feasibility of computed tomography (CT) coronal multiplane reconstruction image (CMRI) to determine subaxial cervical pedicle screw (PS) entry point and guide lateral vertebral notch (LVN)-referred technique for subaxial cervical PS insertion. METHODS: Cervical CT scans were performed in 40 volunteers. PS entry point was determined by quantitating PS entry point related to LVN on CMRI. Pedicle mediolateral angle (a) and cephalocaudad angle (b) were also measured to guide the trajectory of PS insertion. Based on these quantitations, 12 human cadaveric subaxial cervical pedicles were inserted with PS referring to LVN. Cortical integrity of each pedicle was evaluated after dissecting the cadaveric vertebrae one by one and confirmed by radiography and CT. The cortical penetration and PS position were classified into 4 grades: 0 (excellent position), I (good position), II (fair position), and III (poor position). RESULTS: On CT CMRI, PS entry point was consistently located approximately 2.2 mm medial to LVN from C3 to C7 and approximately 1.4 mm lower to LVN from C3 to C6, but 1.2 mm higher at C7. Bilateral a angle and b angle showed substantial decrease from cranial to caudal. Cortical integrity of PS positions was excellent and good in 88.33%, fair in 8.33%, and poor in 3.33%. CONCLUSIONS: CMRI is reliable for determining subaxial cervical PS entry point. LVN is a consistent landmark for the notch-referred technique, which is a practical and easy to master technique for subaxial cervical spine PS insertion.