| Objective:The anatomical parameters of the diameter,cephalad angle,lateral angle and screw length of the normal adult thoracic vertebral cortical bone screw(CBT)are measured,and the ideal screw point and direction of screw are discussed,which provide a theoretical basis for the feasibility of the clinical application of the CBT in the thoracic vertebra.Method:1.Measurement of compututed tomography(CT)images of 80adults:Thoracic 3D image data of 80 adults between 18 and 60 years old(40 for each gender)are randomly selected as subjects of our research,which coming from January 2017 to January 2018 in Chenzhou First People's Hospital thoracic 3D CT examination which reported thoracic and aorta images are normal.the average age is 42.8,of which 40 cases of man,woman 40 cases,the application of ADW4.6 software in every section of thoracic CT measuring screw diameter,screw the angle and inclination angle,the maximum length of the screw head,while measuring the left screw to the shortest distance of aorta.2.The study of digital anatomy:a total of 10 healthy adults(man 5 cases,woman5 cases,age 28~55 years,average 37.8 years old)continuous thoracic CT scandata are imported into Mimics 19.0 software,the construction of thoracic 3D images,simulate the CBT screws,the screws are with the best entry points and screw direction.All datas from segment T1 to T12 are divided into two groups of man and woman,using two independent samples t test,P<0.05 have statistical significance.Result:It is found that the actual lengt of thoracic CBT screw show a trend of increase from segment T1 to T12.the shortest is located in T1,man 22.06±1.25 mm,woman 20.42±1.21 mm,the longest in T12,man 34.07 ±1.99 mm,woman 32.71±0.61mm;lateral angel from segment T1 to T12:T1:8.03±5.25°,T2:0.91±3.41°,T3:-2.76±3.44°,T4:-3.32±2.71°,T5:-3.69±2.83°,T6:-4.35±2.31°,T7:-6.16±2.90°,T8:-6.83±2.29°,T9:-7.95±2.87°,T10:-8.39±2.79°,T11:-9.36±2.90°,T12:-9.81±2.90°.cephalad angle from segment from T1 to T12:T1:22.61 ± 3.51 °,T2:20.59 ±3.99°,T3:18.49±3.73°,T4:18.27±3.28°,T5:17.02±3.34°,T6:16.51±3.00°,T7:17.65±3.30°,T8:19.85±3.28°,T9:22.78±3.19°,T10:24.70±2.99 °,T11:26.98 ± 3.25 °,T12:27.77 ± 3.51 °.Statistical results show that there is a statistically significant difference between men and women(P<0.05)in terms of the length of cross-section of CBT screw,the width of pedicle,the angle of inclinations and the actual screw length.The distance between the three screws and the aorta are compared.The distance between CBT screw and the thoracic aorta on the left of T6 is 6.18±2.17 mm for men and 4.07±1.23 mm for women.The segments closest to the aorta for the CBT,TT and CU via the three screw-cap screws are located at T6,T10 and T12 respectively.Thoracic CBT screw placement point and direction due to the different segments have changed.Conelusion: This study measured the CT image anatomic parameters ofCBT screw of thoracic vertebra,explored the point of entry and the direction of nailing,and the safety of three different methods of nailing and nailing for the thoracic vertebrae are evaluated.The results show that thoracic CBT screws are safe and feasible,and provide a theoretical basis for the use of CBT screws in posterior internal fixation of thoracic vertebrae. |
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