Klippel-Feil综合征寰枕融合和/或C2/3融合致枕颈交界区生物力学变化的有限元分析

Finite element analysis of biomechanical changes in occipitocervical junction caused by atlanto-occipitocervical fusion and/or C2/3 fusion in Klippel-Feil syndrome

中文关键词:  Klippel-Feil综合征  寰枕融合  C2/3融合  Sandwich畸形  生物力学  有限元分析

英文关键词:Klippel-Feil syndrome  Occipitalization of the atlas  C2/3 fusion  Sandwich deformity  Biomechanical  Finite element analysis

中文摘要:

  【摘要】 目的：比较Klippel-Feil综合征（Klippel-Feil syndrome，KFS）中寰枕融合、C2/3融合及二者同时存在时枕颈交界区局部好生物力学变化。方法：选取1名44岁健康成年男性志愿者行颈椎薄层CT扫描，利用Mimics19、Geomagic Studio、SolidWorks及ANSYS 17.0软件提取并建立正常C0-C3上颈椎三维有限元模型（intact upper cervical spine model，INT模型）并进行有效性对比验证，在此基础上通过修改接触及属性的方式建立C2/3融合模型（C2-3模型）、寰枕融合模型（model of occipitalization of the atlas，OA模型）以及二者同时存在的Sandwich模型（Sandwich deformity model，SD模型）。比较4组模型在生理载荷（1.2Nm，1.5Nm，1.8Nm及2.1Nm）下C0-C1、C1-C2、C2-C3节段以及C0-C3活动度改变、横韧带及寰枢关节在各运动状态下的最大Von Mises 应力。结果：与INT模型相比，KFS模型（包括SD模型、OA模型、C2-3模型）的C0-C3整体活动度在4种生理载荷下均有下降，其中SD模型前屈活动度下降41.2%~49.2%、后伸活动度下降39.8%~48.2%、旋转活动度下降20.7%～28.0%、侧弯活动度下降50.8%～56.1%，OA模型前屈活动度下降33.8%~42.9%、后伸活动度下降29.5%~35.1%、旋转活动度下降10.4%～20.3%、侧弯活动度下降40.8%～51.9%，C2-3模型前屈活动度下降14.6%~19.2%、后伸活动度下降16.3%~30.4%、旋转活动度下降17.3%～34.2%、侧弯活动度下降23.2%～42.6%。与INT模型比较，横韧带及双侧寰枢关节应力以SD模型增加最为显著，在前屈状态下分别增加65.5%和123.1%，其次为OA模型，分别增加45.5%和38.5%，最后为C2-3模型，分别增加18.2%和15.4%。旋转活动下SD模型、C2-3模型及OA模型横韧带应力分别增加24.1%、12.7%以及5.1%，侧弯活动分别增加206.7%、166.7%以及140%；寰枢关节应力在后伸状态下SD模型、OA模型及C2-3模型分别增加193.0%、150.0%、56.0%，旋转状态下分别增加63.5%、39.2%、16.4%，侧弯状态下分别增加204.3%、65.2%、160.8%。结论：KFS中寰枕融合和/或C2/3融合在限制上颈椎活动度的同时可显著增加侧方寰枕关节及横韧带结构应力，不同的融合位置与融合节段的数量对上颈椎生物力学改变不同。

英文摘要:

  【Abstract】 Objectives: To assess the biomechanical kinematic and load alterations due to occipitalization of the atlas (OA) and/or C2/3 fusion in patients with Klippel-Feil syndrome (KFS). Methods: A 44-year-old healthy male volunteer was selected and the cervical spine was scanned by thin-slice spiral CT in our hospital. A nonlinear C0-C3 upper cervical spine three-dimensional finite element (FE) model (intact upper cervical spine model, INT model) was developed based on the CT scans using the software of Mimics, Geomagic Studio, SolidWorks, and ANSYS17.0. The validated INT model was altered to include the C2/3 fusion model (C2-3 model), OA model, and Sandwich deformity (SD) model (both OA and C2/3 fusion in one patient). The effect of different segments of fusion under different loading (1.2Nm, 1.5Nm, 1.8Nm, and 2.1Nm) on the range of motion (ROM) of C0-C1, C1-C2, C2-C3, and C0-C3 segment, maximum Von Mises stress in the transverse ligament and facet of atlantoaxial articulation were examined. Results: Compared with the INT model, the KFS model (including C2-3 model, OA model and SD model) resulted in a reduction of overall C0-C3 ROM and an overstress of the transverse ligament and bilateral atlantoaxial joints under the four kinds of physiological loading. The ROM of cervical flexion decreased 41.2%-49.2% by SD model, 33.8%-42.9% by OA model and 14.6%-19.2% by C2-3 model, and the ROM of extension decreased 39.8%-48.2%, 29.5%-35.1%, and 16.3%-30.4%, respectively. The ROM of rotation decreased 20.7%-28.0% by SD model, 10.4%-20.3% by OA model and 17.3%-34.2% by C2-3 model, and the ROM of lateral bending decreased 50.8%-56.1%, 40.8%-51.9%, and 23.2%-42.6%, respectively. Compared with the INT model, the stress of the transverse ligament and atlantoaxial joints increased most significantly in the SD model, by 65.5% and 123.1% respectively in the flexion and extension loading; which was followed by the OA model, by increasing 45.5% and 38.5% respectively; and that in the C2-3 model came the last, by increasing 18.2% and 15.4%. The transverse ligament stress of SD model, C2-3 model, and OA model increased respectively by 24.1%, 12.7%, and 5.1% in rotation loading, and increased by 206.7%, 166.7%, and 140.0% in lateral bending loading. The atlantoaxial joint stress of SD model, OA model, and C2-3 model increased by 193.0%, 150.0%, and 56.0% respectively in the extension loading; increased by 63.5%, 39.2%, and 16.4% in the rotation loading and 204.3%, 65.2%, and 160.8% in bending loading, respectively. Conclusions: The atlantooccipital fusion and/or C2/3 fusion can significantly increase the stress of the transverse ligament and facet of atlantoaxial articulation while limiting the ROM of the upper cervical spine, with different biomechanical kinematic in different number and different fused segments in the upper cervical spine.