Abstract:
Spinal cord stress and strain contribute to degenerative cervical myelopathy (DCM), while cervical kyphosis is known to negatively impact surgical outcomes. In DCM, the relationship between spinal cord biomechanics, sagittal alignment, and cord compression is not well understood. Quantifying this relationship can guide surgical strategies. A previously validated three-dimensional finite element model of the human cervical spine with spinal cord was used. Three models of cervical alignment were created: lordosis (C2-C7 Cobb angle: 20°), straight (0°), and kyphosis (- 9°). C5-C6 spinal stenosis was simulated with ventral disk protrusions, reducing spinal canal diameters to 10 mm, 8 mm, and 6 mm. Spinal cord pre-stress and pre-strain due to alignment and compression were quantified. Cervical flexion and extension were simulated with a pure moment load of 2 Nm. The Von Mises stress and maximum principal strain of the whole spinal cord were calculated during neck motion and the relationship between spinal cord biomechanics, alignment, and compression was analyzed using linear regression analysis. Spinal cord pre-stress and pre-strain were greatest with kyphosis (7.53 kPa, 5.4%). Progressive kyphosis and stenosis were associated with an increase in spinal cord stress (R2 = 0.99) and strain (R2 = 0.99). Cervical kyphosis was associated with greater spinal cord stress and strain during neck flexion-extension and the magnitude of difference increased with increasing stenosis. Cervical kyphosis increases baseline spinal cord stress and strain. Incorporating sagittal alignment with compression to calculate spinal cord biomechanics is necessary to accurately quantify spinal stress and strain during neck flexion and extension.
摘要:
脊髓应力和应变有助于退行性颈椎病(DCM),而宫颈后凸畸形对手术结果有负面影响。在DCM中,脊髓生物力学之间的关系,矢状对齐,和绳索压缩不是很好的理解。量化这种关系可以指导手术策略。使用了先前验证的带有脊髓的人颈椎的三维有限元模型。创建了三个宫颈排列模型:前凸(C2-C7Cobb角:20°),直线(0°),和后凸(-9°)。C5-C6椎管狭窄模拟腹盘突出,将椎管直径减小到10毫米,8mm,和6毫米。量化了由于对齐和压缩引起的脊髓预应力和预应变。用2Nm的纯力矩载荷模拟颈椎屈伸。计算颈运动过程中整个脊髓的VonMises应力和最大主应变与脊髓生物力学的关系,对齐,压缩分析采用线性回归分析。脊柱后凸的脊髓预应力和预应变最大(7.53kPa,5.4%)。进行性后凸和狭窄与脊髓应力(R2=0.99)和应变(R2=0.99)的增加有关。颈后凸与颈屈伸过程中较大的脊髓应力和应变有关,差异的大小随狭窄程度的增加而增加。颈椎后凸畸形增加基线脊髓应力和应变。将矢状对齐与压缩相结合以计算脊髓生物力学对于准确量化颈部屈曲和伸展期间的脊柱应力和应变是必要的。