Mustafy Tanvir, El-Rich Marwan, Mesfar Wissal, Moglo Kodjo
Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB, Canada.
Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB, Canada.
J Biomech. 2014 Sep 22;47(12):2891-903. doi: 10.1016/j.jbiomech.2014.07.016. Epub 2014 Jul 31.
The cervical spine functions as a complex mechanism that responds to sudden loading in a unique manner, due to intricate structural features and kinematics. The spinal load-sharing under pure compression and sagittal flexion/extension at two different impact rates were compared using a bio-fidelic finite element (FE) model of the ligamentous cervical functional spinal unit (FSU) C2-C3. This model was developed using a comprehensive and realistic geometry of spinal components and material laws that include strain rate dependency, bone fracture, and ligament failure. The range of motion, contact pressure in facet joints, failure forces in ligaments were compared to experimental findings. The model demonstrated that resistance of spinal components to impact load is dependent on loading rate and direction. For the loads applied, stress increased with loading rate in all spinal components, and was concentrated in the outer intervertebral disc (IVD), regions of ligaments to bone attachment, and in the cancellous bone of the facet joints. The highest stress in ligaments was found in capsular ligament (CL) in all cases. Intradiscal pressure (IDP) in the nucleus was affected by loading rate change. It increased under compression/flexion but decreased under extension. Contact pressure in the facet joints showed less variation under compression, but increased significantly under flexion/extension particularly under extension. Cancellous bone of the facet joints region was the only component fractured and fracture occurred under extension at both rates. The cervical ligaments were the primary load-bearing component followed by the IVD, endplates and cancellous bone; however, the latter was the most vulnerable to extension as it fractured at low energy impact.
由于其复杂的结构特征和运动学，颈椎起着一种独特的复杂机制作用，对突然加载做出反应。使用韧带性颈椎功能脊柱单元（FSU）C2-C3的生物逼真有限元（FE）模型，比较了在两种不同冲击速率下纯压缩和矢状面屈伸时的脊柱负荷分担情况。该模型是利用脊柱部件的全面且逼真的几何形状以及包括应变率依赖性、骨折和韧带失效的材料定律开发的。将运动范围、小关节接触压力、韧带失效力与实验结果进行了比较。该模型表明，脊柱部件对冲击载荷的抵抗力取决于加载速率和方向。对于所施加的载荷，所有脊柱部件中的应力均随加载速率增加，并集中在椎间盘外层、韧带与骨附着区域以及小关节的松质骨中。在所有情况下，韧带中最高应力出现在关节囊韧带（CL）中。髓核内的椎间盘内压（IDP）受加载速率变化影响。在压缩/屈曲时增加，但在伸展时降低。小关节接触压力在压缩时变化较小，但在屈伸时显著增加，尤其是在伸展时。小关节区域的松质骨是唯一发生骨折的部件，且在两种速率下伸展时均发生骨折。颈椎韧带是主要的承重部件，其次是椎间盘、终板和松质骨；然而，后者在伸展时最易受损，因为它在低能量冲击下就会骨折。
