| Objectives 1.To study the anatomical structure of normal and scoliotic thoracic vertebrae in adolescents aged 12-15 years in Inner Mongolia,to provide detailed information for pedicle screw placement,and to provide data references for screw size design.2.Establish a three-dimensional model of normal and scoliotic spine in adolescents,use the finite element method to analyze the stress of the spine,and observe and analyze the biomechanical distribution of scoliosis.Methods Normal thoracolumbar CT of 120 adolescents aged 12 to 15 years and 30 cases of adolescent idiopathic scoliosis were collected in Inner Mongolia.The raw data of thoracolumbar tomographic images scanned continuously were imported into Mimics21.0 for analysis and measurement in DICOM format.1.Measurement indicators:Pedicle Width、Pedicle Height、Virtual Spike Length、Transverse Diameter of spinal canal、Longitudinal Diameter of spinal canal、The Transverse Pedicle Angle,Maximum Transverse Pedicle Angle、The Sagittal Pedicle Angleand Pedicle Area 2.Select a 13-year-old normal adolescent and a 15-year-old adolescent with scoliosis（thoracic curvature,Lenke1）and perform finite element analysis after 3D reconstruction of the spine.Results Pedicle Width:12～13 years old,T4～T9is relatively narrow,T5、T6is the smallest（male 3.71±0.72,female 3.53±0.60）mm;14～15 years old,T4～T6is relatively narrow,T4、T5is the smallest（male 4.29±0.93,female 4.27±1.20）mm;Pedicle Height:12～13years old,T1～T12gradually increased,T1was the smallest（male 6.19±1.06,female 7.21±2.76）mm,14～15 years old,T1～T11gradually increased,T11～T12decreased,T1was the smallest,（male 7.51±1.55,female 7.48±2.09）mm;Virtual Spike Length:12～13 years old,T1is the smallest（male 29.56±3.24,female 28.25±2.12）mm;14～15 years old,T1 is the smallest（male 31.81±3.43,female 29.60±4.78）mm;Transverse Diamete and Longitudinal Diamete:The two groups are similar in law,T1～T3TD is larger than LD,T4～T7TD is similar to LD,T7～T12TD is smaller than LD;The Transverse Pedicle Angle:The law of the two groups was similar,decreasing at first and then increasing,and the T5～T12angle was less than 5°,almost parallel to the sagittal axis.Maximum Transverse Pedicle Angle:The rules of the two groups were similar,T1～T3decreased rapidly,T4～T7decreased slowly,T7～T12increased slowly.The Sagittal Pedicle Angle:The two groups have similar laws,first increasing and then decreasing,and T5～T8are the largest;Pedicle Area:The two groups have similarities in law,first decreasing and then increasing,and T4～T8are relatively narrow.2.Compared with the convex side,the concave pedicle width is narrower,the virtual nail path is longer,and the external deflection angle of the pedicle is larger.3.The finite element results show that the normal spine stress is mainly concentrated in the middle and posterior columns,and the strain is mainly concentrated in the intervertebral disc;the scoliosis spine stress is mainly concentrated in the concave side,and the strain is mainly concentrated in the intervertebral disc.Conclusions 1.After measuring the pedicle parameters,the imaging parameters of the normal thoracic vertebrae were analyzed and analyzed,which provided a basis for the calculation of screws of suitable size.2.The screw diameter depends on the pedicle width,not the pedicle height.3.The most dangerous site of screw misalignment is the upper middle thoracic spine.4.Compared with the convex side,the pedicle parameters of AIS patients are smaller in width and height on the concave side of the curve,so caution should be taken when inserting screws on the concave side.5.The stress of adolescent idiopathic scoliosis is concentrated on the concave side of the spine curvature,and the strain is mainly concentrated on the intervertebral disc,and the concave side of the curvature is the most obvious,that is,the apical vertebra is the most obvious.6.The asymmetric load on the vertebrae and intervertebral discs is one of the reasons for the source and progression of scoliosis. |
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