Imaging Study On The Adjacent Relationship Between Thoracic Vertebrae And Thoracic Aorta In Adults

【Objective】Pedicle screws have been widely used in the treatment of various spine-related diseases.Compared with lumbar vertebral pedicles,thoracic vertebral pedicles are small,have a large angle change,and are closely related to the position of surrounding tissues.There are many complications of thoracic vertebral pedicle screw placement,one of which is thoracic aortic injury.Although the incidence rate reported in literature is low,once it happens,patients will be in danger of life.This paper intends to measure the relationship between the angle and distance between the thoracic vertebra and the thoracic aorta based on the CT scanning results of the thoracic vertebra,so as to provide data support such as the angle,the depth of screw placement and the safe distance in front of the vertebra for the later discussion and formulation of the screw placement plan of the thoracic vertebra,shorten the learning curve of screw placement,improve the screw placement accuracy of young chiropractors,shorten the operation time,reduce the times of intraoperative fluoroscopy,reduce the complications related to screw placement of the thoracic vertebra,and increase the safety of patients in the operation related to the screw system of the thoracic vertebra.【Methods】This study was a retrospective study.Twenty cases were selected from 2020 to 2021 in the Department of Spine Surgery,The First Affiliated Hospital of Dali University,who met the inclusion and exclusion criteria,and were divided into male and female groups according to gender.（1）the shortest distance from the outer wall of the aorta to the vertebral body a;（2）the minimum distance from the outer wall of the aorta to the left pedicle nailing point b;（3）the vertical distance from the posterior wall of the aorta to the line connecting the two sides of the pedicle nailing point d;（4）the aortic vertebral body angle: the angle α between the line connecting the center point of the aorta and the center point of the vertebral body and the line connecting the two sides of the pedicle nailing point;（5）the medial tangent of the aorta passing through the left pedicle nailing point and the line connecting the two sides of the pedicle nailing point via The angle β between the medial aortic tangent line passing through the left arch nail point and the perpendicular line between the two arch nail points via the left arch nail point;（6）the angle γ between the line connecting the left arch nail point and the central point of the aorta and the perpendicular line between the two arch nail points via the left arch nail point.The test level of α=0.05 was used to test whether there was any difference between the data of each group.Spearman’s correlation analysis was used to analyze the correlation between height and weight and the imaging parameters of each group,and the correlation coefficient was calculated and tested for significance.【Results】Distance a: the minimum distance a from T5 to T8 in both data groups showed a trend of first decreasing and then increasing,the maximum value in the male group appeared in T7 vertebrae with a maximum value of 3.02±1.29 mm,the female group appeared in T5 vertebrae with a maximum value of 3.12±1.74 mm,the minimum distance a minimum value in both groups according to T12 vertebrae,1.75±0.90 mm in males and 1.32±0.51 mm in females.0.51 mm,the two groups differed only in the T10 segment,and the rest of the vertebrae were not different.Distance b: The overall trend of distance b increased gradually from T5 to T12,and the minimum value of distance b in both groups was 26.45±3.62 mm in the male group and 21.96±3.54 mm in the female group,while the maximum value was 47.10±3.33 mm in the male group and 41.95±3.32 mm in the female group.The data of both groups were significantly different,and the data of the male group were generally larger than that of the female group.The maximum value in the female group was 41.50±3.25 mm in the T12 vertebrae,and the minimum value appeared in the T5 vertebrae;the maximum value in the male group was 46.11±3.17 mm in the T12 vertebrae,and the minimum value was 22.02±5.63 mm in the T6 vertebrae.There was no statistical difference in the values of T7,T8 and T9 vertebrae between the two groups,and the remaining vertebrae were different between the two groups.Angular alpha: The overall trend of change was the same in both groups,male and female.The maximum value in both groups was at the T12 vertebral body,64.15±12.20° in male and 63.47±7.91° in female;the minimum value was at the T6 vertebral body,10.85±10.01° in male and4.00±10.68° in female.The two groups differed only in the T6 vertebral body values,and there were no differences in the rest of the vertebral bodies.The angle β and angleγ: the two groups of men and women gradually moved from the outer vertebral body to the inner vertebral body from the T5 vertebral body to the T12 vertebral body,and the thoracic aorta in the T12 vertebral body was in the most inward position in both male and female groups;the most outward position of the thoracic aorta relative to the vertebral body appeared in the T7 vertebral body in both groups.There was no difference between the two angle β and angle γ data T5 to T12.【Conclusion】The overall course of the thoracic aorta is from T5 to T12,and the overall course of the left side of the vertebral body is from anterolateral to posterolateral and then to anteromedial;the closest distance between the aorta and the vertebral body occurs in both groups at the T12 vertebral body;the anterior-posterior position of the aorta from T5 to T12 shows a trend from posterior to anterior,and the farthest anterior-posterior position occurs in both men and women at the T12 vertebral body.The risk of thoracic aorta puncture by pedicle screws at the anterior edge of the vertebral body in the ideal nail placement channel is low,while the risk of external pedicle nail fixation is relatively high;in the T10 to T12 vertebral bodies,the aorta travels on the anteromedial side of the vertebral body,and the risk of double cortical nail placement is high.The location and distance of the thoracic aorta varies greatly among individuals,and the spine surgeon should develop a surgical plan based on the patient’s specific situation when inserting the arch,and should also consider dynamic factors such as the mobility and dilatation of the aorta.