腰部推拿手法生物力学和有限元比较研究

Comparative study of simulated lumbar manipulation techniques using biomechanical and three- dimensional finite element models

目的 应用生物力学方法和三维有限元模型 ,模拟不同腰部推拿手法 ,比较其腰椎内部结构的变化。方法 标本固定于生物力学材料实验机 (MTS)应用计算机定量控制 ,同时使用ABAQUS 6.1有限元软件建立腰椎L4～ 5有限元模型 ,分别模拟斜扳手法、坐位旋转和牵扳手法。结果 生物力学模型显示斜扳手法和坐位旋转手法髓核内压力明显升高 ,牵扳手法髓核内压力降低或轻度升高 ;神经根与椎间盘之间有一位移 ;腰椎小关节内应力低于关节内骨折的限度。有限元模型模拟手法作用时 ,椎间盘的髓核内压力在坐位旋转手法时最大 ;牵扳手法最小且为负值。 3种手法作用时 ,小关节合力均无明显差别。斜扳手法和坐位旋转手法外层纤维环应力最大 ,牵扳手法内层纤维环应力最大 ,3种手法均可造成椎间盘的后外侧与神经根之间有一位移。结论 模拟手法作用时椎间盘与相邻神经根之间有一相对位移 ,这可能是其治疗机制 ,有的手法作用时髓核内压升高 ,应注意其安全性。同时应用三维有限元模型可以很好的模拟各种腰部推拿手法 ,并得到与生物力学实验基本一致的结果。

Objective To study the changes of internal pressure of lumbar disc caused by different simulated lumbar manipulation techn iques exerted on a biomechanical and a three- dimensional finite element models . Methods Seven cadavers′ lumbar spines were loaded on a Material Test System machine, and applied by a computer quantitative contro l to simulate three manipulations. The three- dimensional finite element model of an intact L 4～5 lumbar segment was created using ABAQUS 6.1 software. T h e conditions of rotation manipulation, sitting- rotation manipulation and tract ion- rotation manipulation were simulated. Results I t was shown on the biomechanical model that the pressure within lumbar nucleus p ulposus for rotation manipulation and sitting- rotation manipulation were sign ificantly increased, and the pressure within lumbar nucleus pulposus for tractio n- rotation manipulation were decreased or slightly increased; a displacement b etween the nerve roots and lumbar disc occurred; The stress of lumbar facet were lower than that causing fracture. The finite element model showed that the pres sure within lumbar nucleus pulposus was the highest with rotation manipulation a nd the lowest with sitting- rotation manipulation. The force exerted on the lum bar facet was not obviously different with the three manipulations. Rotation exe rted the largest stress on external annulus fibrosus and sitting- rotation mani pulation on internal annulus fibrosus. The three manipulations caused displaceme nt of disc relative to the nerve root. Conclusion The mechanism of manipulation therapy may be the displacement of the nerve roots re lative to lumbar disc. The pressure in lumbar nucleus pulposus was increased whe n some kind of manipulations were applied. The three- dimensional finite elemen t model can be used for study of different simulated manipulations and get simil ar results to those obtained from the biomechanical model.