Reconstruction And Finite Element Analysis Of The New Dynamic Lumbar- Pedicle Lnternal Fixation System

Objective1 To establish an effective three-dimensional finite element L4～L5 model.2 On the basis of the established three-dimensional finite element lumbar model,simulate the new dynamic lumbar- pedicle internal fixation system implantation and analysis the mechanical properties of the biological fixation uesing the three-dimensional finite element.MethodsOn the basis of CT scan , establish a normal lumbar spine (L4 ~ L5) modle using reverse-engineering software Mimics, solidworks PATRAN and verify its effectiveness, Second,establish the new dynamic lumbar- pedicle internal fixation system of the geometric model by Solidworks software and simulate the process of assembly dynamic internal fixation system into the lumbar spinal ; import the geometric model into the Patran software and conducted meshing, get the finite element mesh model , according to the gray value of the CT lumbar model and material properties of internal fixation, import the assignment model into PATRAN software and obtain the final finite element model.Imposed on the model of axial compression of 500N and 15N ? m torque pre-load and make the model produce flexion, extension, lateral bending, rotation.Using the NASTRAN software, complete the new lumbar - dynamic pedicle fixation system of internal stress distribution and the size of the calculation and analysis in four kinds of operating conditions.On the Hyperview finite element analysis software, show the results and calculate the angle and displacement transfer movement in four kinds of operating conditions and compare the established finite element model with normal lumbar spine modle to evaluate the biomechanical properties. Results1.A normal lumbar spine (L4 ~ L5) three-dimensional finite element was established which was non-discrimination with the model literature reported, the lumbar spine finite element model assembled the new dynamic lumbar- pedicle internal fixation system compared with the normal lumbar spine have some differences in results of the angle of its movement and displacemen.2. In a simulated different pressure, stress distribution of the connecting rod and screws are different . connecting rod stress was significantly higher than the screws, screw-rod stress is significantly higher in rotary situation than other working situation. The sleeve has stress affected in four kinds operating conditions, the stress of scoliosis concave side is significantly higher than the central part convex side.Conclusions1. A effective normal lumbar spine (L4 ~ L5) three-dimensional finite element model was established .2. The new dynamic lumbar- pedicle internal fixation system has a certain range, the connection bar can provide some support ,the sleeve can share the load through the resin to avoid the connecting rod stress fatigue, The new dynamic lumbar- pedicle internal fixation has better biomechanical properties .