Analysis Of Static And Dynamic Characteristics Of Lumbosacral Vertebrae With Pedicle Screw Fixation System

The vertebral fixation system is widely used in the clinical treatment of spinal deformity,trauma and degenerative diseases such as spinal disease,however,there are some problems such as adjacent segment degeneration and pedicle screw breakage after operation,so it is significant to study the biomechanics of lumbosacral vertebrae and internal fixation system.The current research on internal fixation of lumbosacral vertebral model mainly focuses on static analysis,lack of dynamic performance analysis,through the dynamic analysis of the human spine,dynamic characteristics of the spine can be obtained in the condition of vibration,which is conducive to the improvement of screw rod system,this is particularly important for the prevention and rehabilitation of degenerative spinal diseases.This paper based on the CT images,the finite element model of normal lumbosacral vertebrae and lumbosacral vertebrae after internal fixation was established by using Mimics、SolidWorks and ABAQUS software;Then the static and dynamic analysis of the two models is carried out.The static and dynamic performance of the model is studied.1、Through the static analysis: the internal fixation system assumed part of the load on the lumbosacral vertebral body;lower than the upper part of screw rod to bear the greater load;the internal fixation system reduces the scope of activities lumbosacral vertebrae.2、Suggestions for improvement of the existing internal fixation system,in the design of internal fixation system connecting rod,the upper part of the connecting bar is made of smaller rigidity and the lower part is made of larger rigidity,which makes the internal fixation system can not only reduce the load by the lumbosacral vertebrae,but also reduces the internal fixation system on the range of motion restrictions of lumbosacral vertebral,reducing the possibility of adjacent segment degeneration.3、Through modal analysis,the natural frequency of lumbosacral vertebrae after internal fixation are obtained.To avoid resonance,we should try to make the external vibration frequency of human environment away from the natural frequency of lumbar spine.This is more conducive to the rehabilitation of patients with degenerative diseases.4.The amplitude frequency characteristic curves of representative nodes were obtained by the harmonic response analysis.In the frequency range of 11~13Hz,the maximum amplitude of each node in the lumbosacral vertebral model after internal fixation are smaller,obtained that the sensitivity of lumbosacral vertebrae after internal fixation to external vibration was significantly reduced.The results show that the internal fixation system can protect the lumbosacral vertebrae.Based on the characteristics of static and dynamic analysis of normal lumbosacral vertebrae and lumbosacral vertebral model after internal fixation,the internal fixation system and its impact on the spine in the vibration environment were obtained,which can provide reference for the improvement and perfection of the screw rod system,thus it provides reliable technical support for the treatment and rehabilitation of degenerative spinal diseases.