不同运动状态下模拟人体腰椎结构特征变化的有限元分析

目的比较不同运动状态下正常与退变腰椎节段三维有限元模型的应力变化特点及量效关系,分析中医推拿手法对退变腰椎节段力学调衡作用机制。方法建立完整、真实人体脊柱退变腰椎节段(L4~5)三维有限元模型,模拟腰椎节段前屈与后伸的生理活动。在加载外力即中医推拿手法作用下,分析退变腰椎节段的应力变化特点以及外加载荷逐渐递增过程中退变腰椎节段的应力变化,并与正常腰椎节段在不同运动状态下的应力、应变改变趋势进行对比。结果在不同运动状态下,人体腰椎节段椎间盘内应力分布、髓核、纤维环等结构的弹性模量随着腰椎退变程度的增加呈逐渐增大的趋势。中医推拿手法作用后能改变椎间盘内的应力分布,一定程度地增大椎管内的空间,使神经根所受的应力减小,椎体、小关节应力、椎弓根应力后伸位大于前屈位;椎间盘内部应力前屈位大于后伸位;且均由上至下呈逐渐增大的趋势。结论中医推拿手法对人体退变腰椎节段力学环境的调衡起到改善和治疗腰椎间盘病变的目的。同时,与人体正常腰椎节段三维有限元模型对比,从生物力学环境与特性改变角度研究腰椎退变的过程,能够为中医推拿手法在临床中预防和治疗脊柱退行性疾病的推广应用提供科学依据,也为中医推拿手法有效地预防和治疗脊柱腰椎节段病损的生物力学机制的研究提供新研究思路。

Finite element analysis on simulation of change characteristics in human lumbar vertebrae under different motion status

Objective To compare characteristics of stress variations in 3D finite element models of normal and degenerative lumbar vertebrae and the dose-effect relationship, and analyze the mechanism of mechanical balance by traditional Chinese medicine (TCM) manipulation on degenerative lumbar vertebrae. Methods The 3D finite element model of intact, real human degenerative lumbar vertebrae (L4-5) was established to simulate the physiological activity of flexion and extension in lumbar vertebrae. The characteristics of stress variation in degenerative lumbar vertebrae under external loading, namely, the TCM manipulation was analyzed, and the stress variation in degenerative lumbar vertebrae under gradual increasing-external loading was analyzed as well, which was compared with the stress and strain variation in normal lumbar vertebrae under different motion status. Results Under different motion status, the stress distributions on lumbar disc as well as the elastic modulus of nucleus pulposus and fiber ring showed a gradually increasing tendency with lumbar degeneration increasing. TCM manipulation could change the stress distributions on lumbar disc, enlarge the space of spinal canal to a certain degree, and decrease the stress on nerve root. Stresses on small joints of the vertebral body and vertebral pedicle under posterior extension were larger than those under anterior flexion, while stresses on intervertebral disc under anterior flexion were greater than those under posterior extension, which showed a gradually increasing trend from top to bottom. Conclusions The mechanical environment of human lumbar vertebrae can be balanced by TCM manipulation, for the purpose of improving and treating lumbar disc diseases. The comparison with the 3D finite element model of normal human lumbar vertebrae and investigation on lumbar degeneration from perspective of changes in biomechanical environment and characteristics can provide scientific basis for clinic application of TCM manipulation in prevention and treatment of lumbar degenerative diseases, as well as new research idea for studying mechanical mechanism of TCM manipulation in effective prevention and treatment of lumbar lesions.