The feasibility of laminar screw placement in the subaxial spine: analysis using 215 three-dimensional computed tomography scans and simulation software

Abstract Background context There have been several reports describing the usage of subaxial cervical laminar screws. However, the anatomic feasibility of placing such screws has not been thoroughly evaluated yet. Purpose To determine the feasibility of the laminar screw placement in the subaxial cervical spine using a large number of computed tomography (CT) scans and three-dimensional screw trajectory software. Study design Three-dimensional simulation study of screw placement. Patient sample Computed tomography scans of 215 consecutive patients were examined, for a total of 430 screws at each level of the subaxial cervical spine. Outcome measures Successful screw placement without laminar cortical breach, facet joint violation, and collision between two screws in the same level. Methods We simulated the placement of 4.0-mm subaxial (C3–C7) cervical laminar screws. Unilateral and bilateral screw placement was simulated, and their success rates were evaluated at each level of the subaxial cervical spine. This study was not supported by any financial sources. One of the authors received royalties for a posterior cervical fixation system, which is not the topic of this article and is not used or mentioned in this article. Results The success rate of unilateral screw placement was the highest at C7 (91.4%), followed by C6 (31.9%), C3 (30.2%), C4 (6.3%), and C5 (4.0%). It was significantly higher (p