Objective:To simulate the placement of percutaneous cortical bone trajectory (CBT) screws on reconstructed CT images and three-dimensional lumbar model and to measure the morphometric parameters for guiding the placement of percutaneous CBT screws.Methods:The CT images of 100 adult patients with lumbar spine diseases were studied. The CT images were reconstructed using Mimics software. Taking the projection point on the lamina at the junction of the inner and lower edge of the smallest coronal section of lumbar pedicle as the entry point, the cephalad angle, lateral angle, maximum screw length, maximum screw diameter, distance between trajectory and spinous process were measured. At the same time, the relationship between the trajectory and spinous process was observed by using the reconstructed three-dimensional image.Results:The lateral angle of the trajectory from L 1 to L 5 were 9.3° (8.9°, 9.8°), 9.6° (8.9°, 9.8°), 10.4° (9.5°, 11.3°), 11.81°±1.24° and 13.6° (12.5°, 14.5°), respectively. The cephalad angle from L 1 to L 5 were 26.6° (26.0°, 27.0°), 26.2° (25.7°, 26.5°), 26.9° (26.5°, 27.4°), 25.94°±0.92° and 24.3° (22.7°, 25.4°), respectively. Significant statistic differences were found among all levels in the cephalad angles and lateral angles. The mean diameters of the trajectory from L 1 to L 5 were 5.65±0.49 mm, 6.38±0.60 mm, 6.91±0.67 mm, 7.42±0.76 mm and 8.33 (7.59, 9.01) mm, respectively. Except L 1 and L 5, there were significant differences among all levels in the maximum screw diameters. The mean length of the trajectory from L 1 to L 5 were 36.4 (35.4, 37.0) mm, 36.7 (35.8, 37.3) mm, 37.6 (37.1, 38.1) mm, 37.8 (37.3, 38.1) mm and 36.2 (35.2, 36.9) mm, respectively, and there were also significant differences among all levels. The ration in superior endplate for each segment were 41.08% (34.36%, 45.60%), 37.94% (32.97%, 43.63%), 40.18% (34.56%, 44.49%), 38.61% (34.80%, 46.24%) and 40.9% (35.32%, 46.02%), respectively and statistical differences were significant between L 1 and L 2 and L 2 and L 5. The mean distance between the trajectory and the spinous process from L 1 to L 5 were 7.27±1.23 mm, 7.19 (5.97, 8.28) mm, 7.32 (6.01, 8.28) mm, 7.31±1.36 mm and 7.45 (6.32, 8.23) mm, respectively. In the sagittal CT image, the tip of the trajectory located near the posterior two-fifths of the superior end plate, and the extended line of the trajectory located at the inferior edge of spinous process. In the three-dimensional reconstruction model, no obstruction was found between the simulated screws and the spinous process. Conclusion:Lumbar CBT screw can be implanted percutaneously, and spinous process will not hinder the implantation process. Spinous process and upper endplate can be used as a sign to guide the percutaneous CBT screw implantation. Digital analog screw placement can offer a useful reference for the clinical application of percutaneous cortical bone trajectory screw.