Biomechanical Analysis And Study Of Universal Internal Fixation System In Repairing Lumbar Injury

After applications of the MRI data of healthy adult lumbar spine and the reverse engineering software,lumbar models of L3 and L4 are generated.Taking into account the stress relief of the internal fixation system of lumbar patients and over-fixation system during recovery,a new universal pedicle screw fixation system is designed and constructed by the 3D software.Then assemble the lumbar models and the internal fixation system according to the selected angle of the sagittal plane from 0°~10°to obtain the lumbar internal fixation model.The concept of muscle force is introduced which mainly considers the human body's gravity,follower load and erector spinae force.By simulating the lumbar spine in flexion,extension and lateral bending,the influence of muscle force on the stress of the fixation system is analyzed.Change the force loading conditions,assuming that only part of the muscle force is loaded when the spine is injured,obtained internal fixation system and the disc stress,according to the three postures of the human lumbar spine finite element analysis.The stress and displacement values of each part containing without-loading muscle force and loading whole muscle force are compared to achieve the purpose of accurate clinical sagittal nail entry angle range.Based upon the reliability theory and the 6 sigma analysis module in Ansys workbench,the long-term success rate of the internal fixation operation is estimated based on the comprehensive analysis of the material properties and the intervertebral follower load of different bone density and internal fixation system of lumbar spine.It solves the problem that traditional experiments can not carry out a large number of experiments and sample the intended subjects.It also analyzes the patients' intervertebral disk stress in the rehabilitation period and predicts the possibility of postoperative complications.By calculating the stress sensitivity of the internal fixation system,the influence of different factors on the stress of the internal fixation system is obtained,which provides a reference for the development of the new internal fixation system and the selection of the angle of entry into sagittal plane.