T1 intralaminar screws: an anatomic, morphologic study.

In some scenarios, such as complex revisions or tumor cases, intralaminar screw placement in the upper thoracic spine can be used to supplement or replace traditional pedicle screw placement. Despite the theortic feasibility of placing these screws, no thorough anatomic study has evaluated the morphology of the T1 lamina for screw placement.Anatomic data of the T1 lamina, including height, width (the upper, middle, and lower one-third segments), and length (with and without penetration of the facet articulation) were analyzed for 112 T1 vertebrae. The placement of screws with widths of 3.5 or 4 mm and screws with lengths of 24 or 26 mm in the T1 lamina was feasible in all of the laminas measured with the exception of 2 outliers. Furthermore, relationships were found between T1 lamina size and patient height and between T1 lamina size and sex, but no relationship was found between T1 lamina size and race.The morphology of the T1 lamina allows for the simple and safe placement of common screw diameters and is a viable salvage or alternative to the traditional pedicle screw.