Comparing cervical spine movement during intubation with a video laryngoscope versus a standard laryngoscope in cervical spine surgery patients.

- Name: Videolaryngoscopy (ClearVue) with hyper-angulated blade. - Description: Participants in this group undergo endotracheal intubation using the ClearVue videolaryngoscope (Infinium Medical, USA) equipped with a non-channeled, hyper-angulated blade (D-blade, size 3 or 4). A malleable stylet is inserted into the endotracheal tube and pre-curved to 60° to match the blade’s curvature and optical axis. - Procedure details: + Anesthesia: General anesthesia is induced with propofol, fentanyl, and rocuronium. Adequate neuromuscular blockade is confirmed by a Train-of-Four (TOF) ratio of 0% before intubation. + Stabilization: Manual In-Line Stabilization (MILS) is performed by a dedicated assistant to maintain the cervical spine in a neutral position throughout the procedure. + Imaging: Lateral cervical spine images are recorded using fluoroscopy (C-arm) at two specific timepoints: "pre-intubation" (neutral position) and "best glottic view" (static hold just before tube insertion) . + Provider: Intubation is performed by an experienced anesthesiologist. Adherence to the intervention was monitored through a strictly enforced standardized protocol to minimize variability. Specific adherence strategies included: * Objective Monitoring: Neuromuscular blockade was continuously monitored using a TOFscan device, and intubation proceeded only after confirming a TOF ratio of 0%. * Direct Observation: A dedicated research assistant recorded procedural milestones (intubation time) and ensured the assigned laryngoscope was used according to the randomization result. * Imaging Verification: Fluoroscopic images were captured at specific timepoints ("pre-intubation" and "best glottic view") which served as objective evidence that the positioning and stabilization protocols were followed.