Three Internal Fixation Methods For Finite Element Analysis Of Denis Ⅰ Type Of Sacrum Fracture

Abstract:Objective: By means of finite element analysis,the mechanical comparison and analysis of Denis sacral sacral fractures with three internal fixation methods: sacral screw,tension band plate,sacral screw + tension band plate,provides a theoretical basis for the clinical treatment of Denis sacral fracture selection.in accordance with.Methods: One adult healthy volunteer is selected and CT scans of the pelvis are performed.The images are saved in DICOM format.Then the image data is imported into Mimics 19.0 software to establish a normal pelvic three-dimensional model.The Denis iliac patella fracture is established based on the normal pelvic model.Metamodel;using UG14.0 software to draw a tension band steel plate model and a stern screw model;introduce the tension band plate model and sacral screw model into Mimics 19.0,and then assemble it with the simulation Denis sacral fracture model to make the screws,tension band steel plates,and tenon screws + tension band steel plate are three kinds of internal fixation models.In the simulation of human static state in Ansys14.0software,a vertical load of 500 N is applied on the endplate surface of the tibia via restriction on both sides of the acetabulum.Three kinds of internal fixation are compared from the stress,strain and displacement distribution of the pelvis respectively.Model treatment effect.Results1.Under the vertical load of 500 N on the sacral endplate surface,the distribution of iliac stress on both sides of the model pelvis is basically symmetrical.From the force cloud chart of the finite element model of the pelvis,it can be seen that the stress is transmitted from the sacral wing to the white cortex of the bilateral hip.The iliac tendon tends to be fretted relative to the sacrum,and the overall pelvic ring deforms less.The focus is on the sacroiliac joints,Anterior pelvic anterior pubic symphysis and pubic systolic strain is almost zero.2.Stress recovery of three internal fixation models After the three internal fixations are simulated and fixed fractures,the force-cloud diagram showed that the stress distribution of the pelvis is not completely symmetrical,and the stress on the injured side is greater than that on the uninjured side.3.Stress distribution of three kinds of internal fixation modelStress maps show that the three internal fixation methods can effectively restore the biomechanical transfer function of the damaged pelvis.In the three models,the maximum Von Mises stresses are concentrated on the screws of the posterior pelvic fixator:(1)the maximal stress of the sacroiliac screw model is 340.40 MPa,which occurs at the sacral fracture of the screw;(2)the maximum stress of the tension strip model 850.32 Mpa,appear in the bending of the tension band plate and near the nail plate combination site;(3)sacral iliac screw + tension strip model maximum stress of 337.12 Mpa,mainly in the sacral fracture of sacroiliac screws,followed by the steel plate As well as the combination of steel plate and screw.4.Overall Displacement Distribution of Three Internal Fixation ModelsA 500 N load is applied vertically under static conditions and very little strain occurred in all three types of internal fixation.The displacement ofmodel with tension band plate is the largest(9.11mm),the displacement of sacroiliac screw model is second(1.93mm),and that of sacroiliac screw +tension band plate is the smallest(1.78mm).5.Three kinds of internal fixation strain distributionUnder the load of 500 N,the strain of the three kinds of internal fixators is very small: the maximum strain value of sacroiliac screw is 0.03mm;the maximum strain value of tension band plate is 0.09mm;the maximum strain value of sacroiliac screw + tension band plate is 0.01 mm.6.three kinds of internal fixation fracture fracture displacement displacement value.6.Three kinds of sacral vertical displacement after internal fixationThe maximum vertical displacement of the left sacrum after three kinds of internal fixation was 1.21 mm for sacroiliac screw + tension band plate,1.26 mm for sacroiliac screw fixation and 1.36 mm for tension band plate fixation.Conclusion1.The three-dimensional finite element model of normal pelvis constructed using Mimics19.0 and Ansys14.0 software can not only objectively reflect the mechanical characteristics of human pelvis,but also accurately reflect the pelvic anatomy,and can be used for pelvic biomechanics research.2.Through the three-dimensional finite element mechanics analysis,three different internal fixation methods can effectively restore pelvic stability.The stability of sacroiliac screw + tension band plate fixation is greater than that of sacroiliac screw fixation,more than that of tension band plate fixation.