Three-dimensional Finite Element Analysis On The Thoracolumbar Anterior New Dynamic Compression Thoracolumbar Fixation System

Purpose:1、Designing a thoracolumbar spine anterior dynamic pressurized internal fixation system that can generate finite sliding pressurization system at the surface of bone grafting with the purpose of lessening stress shielding from internal fixator to bone grafting fusion area and promoting the forming of new internal fixation system for bone grafting fusion.2 、 Select healthy adult spinal segments T12 to section L2, build their model by finiteelement software,and verify effectiveness model.3、Establish two kinds of Three-dimensional finite element model of anterior titanium mesh and traditional screw-rod internal fixation system and new-type dynamic pressurized internal fixation system under the circumstances L1 burst fracture segments.Study compared two types of internal fixation after forward bends, stretch, lateral bending,torsion, internal fixation and bone graft under vertical load stress distribution,to prove the the effectiveness of the new-type dynamic pressurized internal fixation system to reduce stress shelter and stress concentration, for the next step of physical model experiment in vitro and provide theoretical basis for clinical applicationMethods: Selecting one healthy adult volunteer and going through a CT scan.Then a three-dimensional finite element model is set up by using software, including Mimics, Solidworks, HyperMesh, Abaqus, etc. With previous experiental function of the spinal unit(FSU) average stiffness compared to verify the validity of the model,then it is used to imitate L1 segment burst fractures, so anterior titanium mesh and traditional screw-rod internal fixation system and new-type dynamic pressurized internal fixation system are respectively established,on each model respectively after put forward bends, stretch, lateral bending, torsion, vertical load.Finally, Through the stress pattern observation and contrast are made to obtain stress distribution and theaverage stress and maximum of internal fixator and bone grafting fusion area,stress on the bone under Vertical loads for statistical comparison.Results: 1、Successfully created a healthy adult spine finite element model T12~ L2 segments and through spine unit average stiffness to verify the effectiveness of the model. 2、Successfully established two finite element models of anterior titanium mesh and traditional screw-rod internal fixation system and new-type dynamic pressurized internal fixation system under L1 segment burst fractures.3 、 Two types of internal fixation after forward bends, stretch, and lateral bending, torsion, vertical loading, the stress distribution shows two types of internal fixation of the stress distribution are roughly the same form,internal fixation stress mainly focus on both ends of the titanium mesh and screw the roots and longitudinal connecting rods,by comparing the two types of internal fixation in the internal fixation and bone graft by average and maximum value of stress, internal fixation in the new-type dynamic pressurized internal fixation system by stress is less than conventional screw rod fixation system, and the stress in the bone graft in new-type dynamic pressurized internal fixation system is greater than the traditional screw rod fixation system,and bone graft were under vertical load stress difference is statistically significant(P=0.048<0.05).Conclusion: 1、Design a new-type of thoracolumbar anterior dynamic pressurized internal fixation system.2、Normal T12 ~ L2 segment of the three-dimensional finite element model is proved effective3、In L1 segment,anterior titanium mesh and bone graft traditional screw rod fixation system and new-type of dynamic pressurized internal fixation system in the stress distribution under different load form is roughly same, can provide T12 ~ L2 segment of stability4、New-type dynamic pressurized internal fixation system can lessens stress shielding from internal fixator to bone grafting and effectively improves fusion rate.