A Novel C2 Screw Corridor Parallel to the Sagittal Plane for Transpedicular Fixation – A 3D-CT Study

Abstract

Study Design: A 3D-CT Study. Objective: To research the feasibility and advantages of screw corridors parallel to the sagittal plane (SPC) of the C2 for transpedicular fixation. Summary of Background Data: A total of 125 patients were enrolled for analysis, and the 3D model of the C2 for the 125 patients were reconstructed and analyzed. Methods: The SPC screw and the corridor of the general pedicle (GPC) screw of both sides were inserted into these C2 models. The anatomic parameters of the SPC and GPC, including the inner circle diameter, length of the corridors, medial angle and cephalad angle, were measured and compared. The anatomic location of the entry point for the SPC screw was evaluated. Results: The diameter of the SPC averaged 5.5±1.8 mm; 81.2% (203/250) were larger than 4 mm. There was no significant difference between the SPC and GPC in diameter or percentage of diameter greater than 4 mm. There was a significant difference between the length of the SPC (25.3±2.4 mm) and the GPC (27.4±2.2 mm). The cephalad angle was 51.6±6.9° for the SPC and 43.3±4.4° for the GPC, and there was a significant difference between the SPC and GPC. The entry point of the SPC screw was located on the cortical crest at the lower 1/4 of the lamina and located to the lower and inner side of the GPC screw entry point. Conclusion: It is feasible for most patients to accommodate an SPC screw with a diameter of 3.5 mm. All SPC screws crossed the pedicle completely. The optimal entry point of the SPC screw was located on the cortical crest of the axial lamina.