不同O-EA角枕颈内固定术后下颈椎椎间盘及关节突软骨应力分布的三维有限元分析

Three-dimensional finite element analysis of stress distribution of lower cervical intervertebral disc and articular process cartilage in different O-EA angles after occipitocervical internal fixation

中文关键词:  含外耳道全颈椎模型  枕颈角  有限元  生物力学

英文关键词:Complete cervical model with external auditory canal  O-EA angle  Finite element  Biomechanics

中文摘要:

  【摘要】 目的：构建不同O-EA角（occiput and external acoustic meatus to axis angle）枕颈内固定含外耳道的全颈椎三维有限元模型，观察下颈椎椎间盘及关节突软骨应力分布。方法：收集1例29岁健康男性的含外耳道的全颈椎CT数据，用Mimics 19.0、Geomagic Studio 2015和Solid Works 2018等软件处理，依据O-EA角80°、95°、110°对枕颈内固定系统进行测绘并建立三维模型，构建O-EA角80°、95°、110°并装配有枕颈内固定系统含外耳道的全颈椎三维有限元模型。沿齿状突上方颅底表面施加1.5N·m的力矩，并施加75N垂直力模拟头颅重量，测量前屈、后伸、左侧屈及左旋转工况下C5/6、C6/7椎间盘和C6、C7上关节突软骨Von Mise应力峰值并进行分析和比较。结果：成功建立了不同O-EA角（80°、95°和110°）含外耳道全颈椎三维有限元模型。O-EA角95°枕颈内固定含外耳道的全颈椎三维有限元模型在前屈、后伸和左旋转工况下C5/6、C6/7椎间盘和C6、C7上关节突软骨的Von Mise应力峰值比O-EA角80°和O-EA角110°模型小；左侧屈工况下，C5/6椎间盘以及C6、C7上关节突软骨Von Mise应力峰值O-EA角95°模型比O-EA角80°和110°模型大，C6/7椎间盘Von Mise应力峰值O-EA角95°模型比O-EA角110°模型大而比O-EA角80°模型小。结论：三维有限元分析结果提示枕颈内固定术中应注意O-EA角大小，O-EA角不恰当可能造成C5/6、C6/7椎间盘和C6、C7上关节突软骨的Von Mise应力峰值增加，进而加速下颈椎的退变。

英文摘要:

  【Abstract】 Objectives: A three-dimensional finite element model of the whole cervical spine with external auditory canal of occiput and external acoustic meatus to axis angle(O-EA angle) of 80°, 95°, and 110° and equipped with occipitocervical internal fixation system was constructed to study the stress distribution of the lower cervical intervertebral disc and articular process cartilage. Methods: Based on the CT source data of the total cervical spine with external auditory canal of a 29-year-old healthy man, and computed by Mimics 19.0, Geomagic Studio 2015, and Solid Works 2018 software, to establish a three-dimensional finite element model of the whole cervical spine with external auditory canal of O-EA angle of 80°, 95°, and 110° and equipped with occipitocervical internal fixation system. A net torque of 1.5N·m was applied along the skull base surface above the odontoid process, and 75N was applied to simulate skull weight. The stress peaks of C5/6 and C6/7 intervertebral discs and the articular cartilage of C6 and C7 under the conditions of forward flexion, posterior flexion, left flexion and left rotation were measured and compared. Results: The finite element analysis model with external auditory canal was successfully established to simulate occipital and cervical fixation at different O-EA angles(80°, 95°, and 110°). The Von Mise stress peak values of C5/6, C6/7 intervertebral discs, and C6, C7 superior articular process cartilages under flexion, extension and left rotation conditions were smaller than those of the models with O-EA angle of 80° and 110°. Under the left flexion condition, the stress peak of the C5/6 intervertebral disc and the upper articular process of C6 and 7 at O-EA angle of 95° was greater than that at O-EA angle of 80° and 110°, while the stress peak of the C6/7 intervertebral disc at O-EA angle of 95° was greater than that at O-EA angle 110° and less than O-EA angle 80°. Conclusions: The results of three-dimensional finite element analysis indicate that the O-EA angle should be paid attention during occipitocervical internal fixation. The improper O-EA angle may cause the increase of Von-Mise stress peak value of C5/6, C6/7 intervertebral disc and C6, C7 superior articular process cartilage, and then accelerate the degeneration of the lower cervical spine.