经口寰枢椎前路钢板固定有限元分析及临床意义

目的　对经口寰枢椎钢板前路固定力学参数进行有限元分析，为该节段手术的开展及改进提供参考。 方法　随机选取2014年1月来本院就诊检查的非颅底-寰枢椎疾患病例1例，男性，36岁，体质量64 kg。对颅底-寰枢椎进行0.625 mm薄层扫描，采用Mimics 16.01软件对影像资料进行重建，利用Pro/ENGINEER 4.0软件对经口寰枢椎前路钢板进行重建，将重建后的钢板螺钉三维模型导入Mimics 16.01中按照经典经口寰枢椎前路手术要求进行配准，并对模型进行面、体网格划分和材料赋值，将模型导入ANSYS14.0软件内，垂直方向加载80 N，表面施加15 Nm力矩，模拟前屈、后伸和侧弯3种运动状态，测量螺钉和棒的应力。 结果 寰枢椎三维重建模型共划分39 842个体网格，对模型进行加载后，上位螺钉根部前屈最大应力为（62.34±5.52）MPa （F=73.23,P<0.05）; 下位螺钉根部和顶端侧弯最大应力分别为（78.42±5.5.14）Mpa（F=112.32, P<0.05）；（95.48±7.12）Mpa（F=62.32, P<0.05），差异均有统计学意义；前屈和后伸状态下上位螺钉根部应力大于下位（t前屈=12.2，t后伸=9.23，t侧弯=-22.98，均P<0.05），而在侧弯时下位螺钉根部应力大于上位；下位螺钉顶端与根部在相同运动状态下比较，顶端大于根部，差异均有统计学意义（t前屈=23.14，t后伸=22.01，t侧弯=8.13，均P<0.05）。 结论 经口寰枢椎固定系统应力分布较为合理，能承受正常寰枢椎运动承载的应力，但术后患者要减少前屈和侧弯运动，以降低固定系统疲劳断裂的风险。

The finite element analysis and clinical significance of through the mouth atlanto-axial vertebral anterior plate fixation

Objective　To analyze through the mouth atlanto-axial vertebral anterior plate fixation in finite element for the development of the segmental anterior fixation surgery and to provide the reference of inner plant improvement.　Methods　One case, male, 36 years old, 64 kg weight was randomly selected in January 2014 in our hospital, whom was excluded of the skull-atlanto-axial vertebral disease. The patient received scanning with a thickness of 0.625 mm; Image data were rebuilt in the Mimics16.01 software and Pro/ENGINEER4.0 software was used to rebuild the atlanto-axial vertebral anterior plate. After reconstruction of steel screw 3D model according to the classic through the mouth,the model was imported into Mimics16.01 and the model surface was meshed and material assigned. The model was then imported into Ansys14.0, and was forced 80 N vertical loading. The surface was applied 15 Nm torque to simulate three-motion state example, forward bends, stretch, side-bending. The stress and deformation of screw and rod were measured. Results　Atlanto-axial vertebral three-dimensional reconstruction model were divided into 39842 individual grid and the model was loaded. The stress of upper screw root in bend was biggest (62.34 ±5.52) Mpa (F=73.23, P<0.05, the difference was statistically significant).A screw of the root and the top, lateral stress was the largest, respectively were (78.42±5.5.14) Mpa (F=112.32, P<0.05);(95.48±7.12)Mpa (F= 62.32, P<0.05), the difference had statistical significance; Under three different motion state and a screw root stress, Upper screw root stress in bending forward was greater than the lower (forward bends, stretch and lateral bending state , t value were 12.2, 9.23, 22.98, P<0.05, differences were statistically significant), and in the lateral current screw root stress was greater than the upper; In the same movement state, the top was greater than the root, the differences were statistically significant (forward bends, stretch and lateral bending state after t value were 23.14, 22.01, 8.13, P<0.05).　Conclusion Through the mouth atlanto-axial vertebra fixed system stress distribution was more reasonable, could withstand normal atlanto-axial after vertebral motion bearing stress, but the postoperative patients should reduce the proneness and lateral movement to lower the risk of fatigue fracture fixation system.