颈椎关节突关节矢状角不对称对颈椎间盘纤维环应力影响的三维有限元研究

Three-dimensional finite element study of the effect of sagittal angle asymmetry of cervical facet joint on the stress of cervical intervertebral disc annulus fibrosus

中文关键词:  关节突关节矢状角不对称  颈椎间盘  纤维环  应力  有限元分析

英文关键词:Facet tropism  Cervical intervertebral disc  Annulus fibrosus  Stress  Finiteelement analysis

中文摘要:

  【摘要】 目的：利用有限元技术探究颈椎关节突关节矢状角不对称对颈椎间盘纤维环和关节突关节的应力影响。方法：选择一名26岁健康女性志愿者的颈椎CT扫描数据构建颈椎有限元模型。首先，构建C3-C7的颈椎正常模型，该模型通过先前发表的研究数据进行了验证。其次，提取C5-C6的数据，并改变C5-C6关节突关节矢状角的角度以重新构建实验模型。重新构建成三个模型，包括对称模型（左右两侧矢状角均为90°），中度颈椎关节突关节矢状角不对称（facet tropism，FT）模型（左侧矢状角100°，右侧90°），重度颈椎FT模型（左侧矢状角110°，右侧90°）。在每个模型中，分别施加四种纯扭矩和复合扭矩以研究FT对椎间盘纤维环应力和关节突关节压力的影响。结果：在前屈、后伸、左右侧屈、左旋和前屈结合左旋的扭矩下，三个模型的椎间盘纤维环纤维应力和关节突关节压力差异无显著性。但在右旋和前屈结合右旋的扭矩下，三个模型的椎间盘纤维环纤维应力和关节突关节压力有显著差异，与颈椎关节突关节对称模型相比，中度颈椎FT模型和重度颈椎FT模型的纤维环纤维应力呈增加趋势（右旋扭矩下分别增加16.65%和35.16%；前屈结合右旋扭矩下分别增加了19.47%和54.39%），且重度颈椎FT模型增加更明显；关节突关节压力呈减少趋势（右旋扭矩下分别减少了3.31%和5.95%；前屈结合右旋扭矩下分别减少了7.19%和15.52%），且重度颈椎FT模型减少更明显。结论：颈椎关节突关节矢状角不对称会增加椎间盘纤维环的应力，并且不对称程度越大，应力增加越明显，可能是颈椎间盘退变或突出的病理解剖学因素之一。

英文摘要:

  【Abstract】 Objectives: The effects of facet tropism on cervical intervertebral disc and facet joint were investigated by finite element analysis. Methods: The finite element model was constructed using CT scans of a 26-year-old female volunteer. Firstly, a cervical model was constructed from C3 to C7. The model was verified using data from previously published studies. Secondly, the facet orientation at C5-C6 level was altered to simulate the facet tropism with respect to the sagittal plane. Three models were reconstructed, including symmetric model(90° facet joint angle at the both side), moderate facet tropism model(100° facet joint angle at the left side and 90° facet joint angle at the right side), and severe facet tropism model(110° facet joint angle at the left side and 90° facet joint angle at the right side). In each model, the stress of annular fiberswere studied under four pure moments and combined loading. Results: Three models just had little differ on the stress of annulus fiber and the pressure of facet joint under flexion, extension, lateral bending, left rotation and flexion combined with left rotation moment. But under right rotation and flexion combined with right rotation moment, there were significant differences in the stress of annulus fiber and the pressure of facet joint among the three models. Compared with the symmetric model, the annular fiber stress of moderate facet tropism model and severe facet tropism model showed an increasing trend(increased by 16.65% and 35.16% respectively under right axial rotation; flexion combined with right axial rotation increased 19.47% and 54.39%, respectively), and severe facet tropism model was more obvious. The pressure of facet joint showed a decreasing trend(reduced by 3.31% and 5.95% respectively under right axial rotation; flexion combined with right axial rotation reduced by 7.19% and 15.52%, respectively), and the decrease was more obvious in the severe facet tropism model. Conclusions: Cervical facet tropism increases the stress of intervertebral disc annulus fiber, and the greater the degree of facet tropism, the more obvious the stress increases, it may be one of the pathological anatomic factors of cervical disc degeneration or herniation.