Effect of different attributes of the mimic human lumbar spine biomechanics material structure change by finite element analysis

Abstract

Background In this study, we compared stress changes and quantity effect relationships from 3D finite element models of normal and degenerative lumbar segments. We further defined the mechanisms causing alterations in mechanical stability the control of normal and degenerative lumbar segments using traditional Chinese medicine. Objective The characteristics of the stress change and the quantity effect relationships of the three-dimensional finite element model of normal and degenerative lumbar segments were compared. The mechanism(s) leading to changes in mechanical stability and the intervention and balance between normal and degenerative lumbar segments of the traditional Chinese medicine was analyzed. Methods A 3D-FEM of degenerative lumbar segments L4~5 of the human spine was established to simulate the physiological and pathological changes of the lumbar spine in response to flexion, extension, lateral bending and torsion. The stress changes in the normal and degenerative lumbar vertebrae were assessed through external force interventions and the response to TCM. Stress in the degenerative lumbar vertebrae changed according the external load. Stress and strain were compared in the FEM model under a range of motion states. Results Components of the human lumbar vertebrae including the cortical vertebrae, cancellous bone, endplates, fibrous rings, and facet articular processes were investigated. The elastic modulus of the nerve roots and the posterior marginal structures of the vertebral body increased with lumbar degeneration. The stress distribution in the intervertebral discs were influenced by TCM, and the space in the spinal canal enlarged so that nerve root stress decreased, vertebral body stress increased, and facet processes and pedicle stress in the posterior regions exceeded those of the anterior flexion position. The internal stress of the intervertebral disc increased in the flexion compared to the extension position, gradually increasing from top to bottom. Conclusion TCM can improve and treat lumbar disc disease through its ability to regulate the mechanical environment of degenerative lumbar vertebrae. Compared to the FEM models of the lumbar vertebrae, lumbar degenerative changes could be assessed in response to alterations in the biomechanical environment. These findings provide a scientific basis for the popularization and application of TCM to prevent and treat spinal degenerative disease.