Abstract:Objective: To reconstruct the CT measurements and cross section anatomy, explore the atlas of the nail into the position accurately, to determine the nail into the constant reference frame, and based on the selected reference frame and into the nail Angle relationship of measurement to determine the direction and point of view, for the atlas pedicle nailing technology to provide the anatomical and clinical operation reconstruction CT data reference. Methods: 20 atlas specimens of 40 sides were measured with vernier calipers and protractors. The atlas three-dimensional CT images of 20 normal subjects were measured with GE Light Speed 64 Pro spiral CT operating software (ADW4.2). Results: The reconstructed CT and sectional anatomical measurements showed that: the thinnest width of the posterior arch at the base of the atlas vertebral artery sulcus (w) > its height (H), the height of the arch was H4.6±1.5mm), the height of the arch was 4.5±1.3mm, the width of the arch was 9.5±2.0mm, and the width was 8.9±1.9mm. The transverse distance between the screw entry point and the posterior tubercle of the posterior arch of the atlas is S1:21.2±3.5 mm and 20.8±3.6 mm. The length of atlas screw track (AB): 26.1±4.4 mm; 25.6 ±3.9 mm. The distances between the inner and outer edges of the dorsal mass of the atlas are S2:11.1±1.1 mm and 11.5±1.2 mm. Longitudinal angle of nail track (Y): 4.1±0.7, 4.7±0.9, transverse angle of nail track (X): 10.9±5.2, 10.2±4.6. The distance from the medial wall of the transverse foramen to the outer edge of the spinal canal was S3:8.0+1.4 mm and 7.8±1.5 mm. There was no significant difference between the two parameters (P > 0.05). Conclusion: The results of anatomical measurement and reconstructed CT were consistent. The projection distance between the middle point of the distance between the inner edge and the outer edge of the lateral mass of the upper arch and the thinnest point of the posterior arch at the bottom of the vertebral artery sulcus was 2 mm. The longitudinal angle of the screw was 3 to 5 degrees, and the transverse angle was 6 to 16 degrees; the length of the screw was 21.7 degrees. 3.5mm in diameter and 30.5mm in diameter are objective, safe and reliable. Meanwhile, three-dimensional reconstruction CT can provide more specific and individualized reference for nail placement.