Objective To study the anatomical structure of normal and scoliotic thoracic vertebrae in adolescents aged 12-15 years in Northern Shanxi Province, to provide detailed information for pedicle screw placement, and to provide data references for screw size design. Methods Totally 120 cases of normal thoracolumbar CT of 120 adolescents aged 12 to 15 years and 30 cases of adolescent idiopathic scoliosis were collected in Northern Shaanxi Province. The raw data of thoracolumbar tomographic images scanned continuously were imported into Mimics16.0 software for analysis and measurement in DICOM format. Measurement indicators: pedicle width, pedicle height, pedicle length, transverse diameter of spinal canal, longitudinal diameter of spinal canal, transverse pedicle angle，maximum transverse pedicle angle, sagittal pedicle angle and pedicle area. Results Pedicle width：12-13 years old, T4-T9 were relatively narrow, T5,T6 were the smallest［male (3.71 ±0.72) mm, female (3.53 ±0.60) mm］；14-15 years old, T4-T6 were relatively narrow, T4,T5 were the smallest ［male(4.29 ±0.93) mm, female (4.27 ±1.20) mm］；Pedicle height:12-13 years old, T1-T12 gradually increased, T1 was the smallest ［male (6.19±1.06) mm, female(7.21±2.76)mm］, 14-15 years old, T1-T11 gradually increased, T11-T12 decreased, T1 was the smallest ［male (7.51±1.55) mm, female (7.48 ±2.09) mm］；Virtual spike length：12-13 years old, T1 was the smallest ［male (29.56 ±3.24) mm, female 28.25 ±2.12） mm］；14-15 years old, T1 was the smallest ［male (31.81 ±3.43) mm, female 29.60 ±4.78）mm］； Transverse diameter and longitudinal diameter：the two groups were similar in law, T1-T3 TD was larger than LD, T4-T7 TD was similar to LD, T7-T12 TD was smaller than LD；The transverse pedicle angle：The law of the two groups was similar, decreasing at first and then increasing, and the T5-T12 angle was less than 5°, almost parallel to the sagittal axis. Maximum transverse pedicle angle: the rules of the two groups were similar, T1-T3 decreased rapidly, T4-T7 decreased slowly, T7-T12 increased slowly. The sagittal pedicle angle：The two groups had similar laws, first increasing and then decreasing, and T5-T8 were the largest； Pedicle area：the two groups had similarities in law, first decreasing and then increasing, and T4-T8 were relatively narrow. Compared with the normal spine, compared with the convex side, the concave side pedicle width was narrower, the virtual nail tract length was longer, and the pedicle external deflection angle was greater. Conclusion The analysis of the pedicle parameters of the thoracic spine shows that the appropriate size of the screws for each thoracic spine and the characteristics of the parameters of the scoliotic pedicles can help clinicians master the anatomical structure of the thoracic spine and improve the accuracy of clinical surgery.
