枢椎的

［Objective］ To investigate the stability and function of atlantoaxial segment after atlas odontoid process artificial joint replacement.

［目的］测试寰椎齿状突人工关节置换后寰枢椎的稳定性和功能。

Results: Under the two boundary conditions, finite element analysis results demonstrated that the ossification degree of the subdental synchondrosis did not obviously influence the high stress distributions, as well the maxium von Mises equivalent stress.

结果：两种约束条件下，枢椎有限元计算预测结果发现枢椎软骨基质的融合程度对枢椎高应力集中带分布无明显影响，最大von Mises等效应力值改变亦不明显。

Results Seven cases were basilar impression,nine cases were dearticulation of atlantoepistrophic articulation,and five caces were Chiari abnormity.In the X-ray pictures,it showed the abnormal form of the atlas and axis,it also showed the Chamberlain line, according to which we could diagnose the basilar impression.

结果 21例中，颅底凹陷为7例，寰枢椎脱位9例，Chiari畸形5例。X线平片主要表现为寰椎、枢椎形态构异常，并且能显示Chamberlain线，借此可作出颅底凹陷的诊断。

Methods A total of 15 cases were fixed and fused with lateral mass screw of atlas and vertebra dentata pedicle screw.

方法采用寰椎侧块螺钉与枢椎椎弓根螺钉技术对15例寰枢椎不稳的患者进行固定。

Objective To summary the results of fixation and fusion with lateral mass screw of atlas combined with vertebra dentata pedicle screw for treatment of atlantoaxial instability and discuss the corresponding therapy methods.

目的总结侧块螺钉与椎弓根螺钉技术治疗寰枢椎不稳的效果，探讨寰枢椎不稳的固定方法。

The new idea, such as the"rotation"of atlas in 3 direction in some of AADs with intact axis, vertebrated odontoid, complete dislocation of AADs with detached odontoid, and differentiation of"dislocation of atlantoaxial joint"and"stenosis of canal"in atlantoaxial subluxation with detached odontoid, are established in this report.

1、本研究提出了一些新的概念，如枢椎完整型AADs时其寰椎在三个方向上的&旋转&脱位、椎体化齿突畸形、齿突不连型AADs的完全脱位、齿突不连的寰枢半脱位时&脱位&和&狭窄&的区分、枕大孔不规则狭窄等为本研究的新的发现或提出的新概念。

Screws and plates in the pedicles of atlas and axis can make the atlantoaxial joint stable in three - dimension immediately.

结论采用寰枢椎椎弓根钉板固定可以使寰枢椎即刻得到坚强的三维稳定，是一种值得推广应用的手术方法。

The odontoid vertebra space in the model was divided into lattices and the stress area of the odontoid vertebra was identified by force loading and analyses. It was found that the structure of the stress concentration area was closely related to the development of split sections. Therefore,when the odontoid process is attacked by the external force along its vertical plane,its waist is likely to break and type II fracture occurs. And the break also possibly appears in its base,in this way,type HI fracture occurs.

确定其材料性质、单元类型并控制好网格划分精度后，通过力的加载与分析，找出枢椎的结构应力区，根据结构的应力集中区与其断裂时断裂面走向的密切关系，从而判断出当外部载荷沿齿突中性矢状面不同角度作用，即齿突受到来自其矢状面的外部冲击时，容易在齿突腰部发生断裂，形成枢椎齿突Ⅱ型骨折，也可能在基底部发生断裂，形成枢椎齿突Ⅲ型骨折。

From the simulations, we can see the distributions and transmission of strain and stress in model under different loadings, and the results explained the fractures very well. 4. Similarly, a axis FEM model was constructed to simulate the axis fracture, emphasized on the odontoid process. Three kind of odontoid process fracture were analysed on this model, which occurred respectively on the tip, the middle and the fundus. The results gave the best angle to fracture the odontoid process of the axis.

四、建立了枢椎的三维有限元模型，对枢椎齿状突骨折机理进行了理论上的研究，重点针对临床上齿突骨折的三种分类：1、齿突尖骨折；2、齿突腰部骨折；3、齿突基底部骨折，赋予齿状突在矢状面沿各种角度下受力条件，模拟衰椎前弓、襄椎横韧带以及CZ－3棘间韧带对枢椎造成的暴力破坏，确定了最可能引起齿状突暴力骨折的受力角度。

Similarly, a axis FEM model was constructed to simulate the axis fracture, emphasized on the odontoid process. Three kind of odontoid process fracture were analysed on this model, which occurred respectively on the tip, the middle and the fundus. The results gave the best angle to fracture the odontoid process of the axis.

四、建立了枢椎的三维有限元模型，对枢椎齿状突骨折机理进行了理论上的研究，重点针对临床上齿突骨折的三种分类：1、齿突尖骨折：2、齿突腰部骨折：3、齿突基底部骨折，赋予齿状突在矢状面沿各种角度下受力条件，模拟寰椎前弓、寰椎横韧带以及C2-3棘间韧带对枢椎造成的暴力破坏，确定了最可能引起齿状突暴力骨折的受力角度。

In the negative and interrogative forms, of course, this is identical to the non-emphatic forms.

。但是，在否定句或疑问句里，这种带有"do"的方法表达的效果却没有什么强调的意思。

Go down on one's knees;kneel down

屈膝跪下。。。下跪祈祷