基于Coflex改良设计棘突间动态固定系统的有限元分析

摘要

BACKGROUND:The Coflex is widely used in China, but it has a high complication rate of spinous process fracture. OBJECTIVE:With the help of finite element analysis, to verify if rigid restriction of spinous process contacts in modified Coflex design is semi-rigid restriction so as to reduce the stress of spinous process in spine flexion and extension, lateral bending and rotation and to decrease the risk of spinous process fracture. METHODS:The images were extracted from patients who had undergone abdomen CT scans in the Beijing Chaoyang Hospital affiliated to Capital Medical University. Three-dimensional finite element model of lumbar spine was established. The Coflex model and the corresponding modified Coflex model were established and then simplified in the SolidWorks software of CAD. Tensile force, shearing force and axial rotating force in resting state were analyzed in ANSYS software. RESULTS AND CONCLUSION:Under tensile force, transversal shearing force and axial rotating force, compared with Coflex system, the stress of spinous process model was reduced in the modified system (P < 0.01). These findings indicate that the forces of the modified model are superior to the force of Coflex. It can reduce stress in the spinous process under stresses and diminish the occurrence of spinous process fractures.%背景：国内应用较广的棘突间动态系统Coflex存在较高的棘突骨折并发症发生率。目的：通过有限元分析，验证改良的Coflex设计中与脊柱棘突的接触中的刚性限制，为半刚性限制，从而减少在脊柱屈伸，侧屈及旋转活动中棘突的受力情况，降低棘突骨折的发生。方法：提取首都医科大学附属北京朝阳医院影像系统中腹部CT扫描患者的图像，建立腰椎三维有限元模型；通过精密仪器测量在CAD软件SolidWorks软件中建立Coflex及改良后的系统模型；在SolidWorks软件中进行棘突模型简化，在ANSYS软件中分析假体模型在拉力、剪切力和轴向旋转力作用下的静态受力情况。结果与结论：在拉力、横向剪切力和旋转力作用下，与Coflex系统相比，改良后的系统中棘突模型应力明显减小(P <0.01)。说明改良后的模型在棘突骨骼受力方面均优于原方案，能够减少在脊柱受力情况下的棘突应力，降低了棘突骨折的发生。