Guo Li-Xin, Teo Ee-Chon
School of Information Science and Engineering, Northeastern University, Shenyang, People's Republic of China.
J Spinal Disord Tech. 2006 Apr;19(2):118-24. doi: 10.1097/01.bsd.0000191527.96464.9c.
A three-dimensional finite element (FE) model of the lumbar spine L3-L5 segment, the ligaments of which were assumed to be nonlinear materials, was established based on the actual vertebra geometry to investigate the influence of the injury lumbar spine on its adjacent components on the condition of whole-body vibration. Several injury conditions of the spine components were assumed, such as facetectomy, nucleotomy, and removal of bony posterior elements.
The dynamic FE analyses were carried out for those FE conditions under cyclic compression loads at the frequencies of 5 and 10 Hz. Then a comparison between the dynamic results and the static results was conducted to analyze the influence of both the nucleus injury and the facet joint injury on the adjacent intervertebral discs.
The results indicate that the lumbar spine exhibits not only vertical vibration but also the flexion--extension motion during vibration. The denucleation will cause high stress and large disc bulge on the disc annulus under vibration. The facet joints of lumbar spine can limit the motion amplitude of flexion-extension and protect both the posterior regions and the posterolateral regions of disc annulus from large strain and stress during vibration. The facet joint removal will increase the stress of disc annulus by around 15% at the posterior region for the conditions of nucleotomy or no vibration. The stress of annulus circumference is higher at the posterolateral region than that of other regions of annulus circumference, and the facet joint removal may exacerbate the intervertebral disc degeneration on the condition of whole-body vibration.
基于实际椎体几何形状建立腰椎L3 - L5节段的三维有限元（FE）模型，其中韧带假定为非线性材料，以研究在全身振动条件下，损伤的腰椎对其相邻部件的影响。假定了脊柱部件的几种损伤情况，如小关节切除术、髓核切除术和去除椎骨后部元件。
在5Hz和10Hz频率的循环压缩载荷下，对这些有限元条件进行动态有限元分析。然后对动态结果和静态结果进行比较，以分析髓核损伤和小关节损伤对相邻椎间盘的影响。
结果表明，腰椎在振动过程中不仅表现出垂直振动，还表现出屈伸运动。髓核摘除术会导致振动时椎间盘纤维环上出现高应力和大的椎间盘膨出。腰椎小关节可限制屈伸运动幅度，并在振动过程中保护椎间盘纤维环的后部区域和后外侧区域免受大应变和应力的影响。在髓核切除术或无振动的情况下，小关节切除会使椎间盘纤维环后部区域的应力增加约15%。纤维环圆周的后外侧区域的应力高于纤维环圆周的其他区域，并且在全身振动条件下，小关节切除可能会加剧椎间盘退变。
