| Objective:Using MIMICS software to reconstruct the 3-D model of normal pelvis simulation screw implant pelvic model analysis LC-?screw channel and channel parameters,provide theoretical basis for clinical screw implant.Methods:The 3d CT data of the normal pelvis(DICOM format)from September 2016 to December 2018 in our hospital were collected,and the data of pelvic fractures,tumors,congenital malformations and other diseases,and the age <18 years old were excluded.Male 28 cases.Female 21 cases.Data import MIMICS 20 software,3 –D model reconstruction of the pelvis,and iliac spine under lateral before rim midpoint as the needle point(marked as "O")in the direction of the posterior spine simulation screw placement,all screw nail into consistent,set screw diameter of 6.5 mm,will wear out ilium cortex,into the joint screw out,remain in the iliac screw)in the cortex,the length of the adjusting screw to screw tail coincided with ilium trailing edge tangent and not through the cortex.The area enclosed by the screw is the screw channel.Find out the critical screw(OA,OB,OC)which is tangent to the bone cortex but does not penetrate the cortex and is located at the turn of the channel,and observe the characteristics of the screw channel.Then the pelvic model and the simulated screws were imported into the 3-matic 12 software,and the lengths of the three screws,the included angles with the sagittal plane and the cross section were measured.Results: After 3-D reconstruction and measurement of all pelvic CT data,it can be found that the screw channel is approximately tetrahedral,in which the length of screw OA is 139.73±7.48 mm in males and 134.23±7.34 mm in females,the difference is statistically significant.The length of screw OB was 114.43±6.38 mm in males and 109.46±7.34 mm in females,and the difference was statistically significant.The length of screw OC was 83.96±7.82 mm in males and 87.26±8.62 mm in females,with no significant difference.The included Angle between screw OA and sagittal plane was 21.38±3.09 ° in males and 18.99±3.75 ° in females,with statistically significant difference.The Angle between the screw OB and the sagittal plane was 26.30±3.84 ° in males and 25.75±3.60 ° in females,with no significant difference.The Angle between screw OC and sagittal plane was 35.01±4.52 ° in males and 32.05±3.97 ° in females,and the difference was statistically significant.The Angle between screw OA and cross section was 37.31±6.40 ° in males and 41.95±6.32 ° in females,and the difference was statistically significant.The Angle between the screw OB and the cross section was 16.28±4.98 ° in males and 22.36±5.40 ° in females,and the difference was statistically significant.The Angle between screw OC and sagittal plane was 22.89±4.77 ° in males and 29.00±5.93 ° in females,and the difference was statistically significant.Conculsion: When into the nail fixed before the iliac spine lateral edge point,put the safety of the screw area roughly the line into a tetrahedron osseous channel,within the screw length shorter than throughout the rest of the obvious,with sagittal plane Angle is bigger also,so with nailing as far as possible in the sagittal plane Angle between 25 to 30 °,and cross-sectional Angle is between 25 to 30 ° safer as far as possible. |
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