寰枕融合下的颅颈交界区有限元生物力学分析

摘要

Objective To study the biomechanical change of the craniovertebral junction in conditions of atlas assimilation.Methods Mimics software was used to process CT data of the craniovertebral junction in a health adult to obtain the three-dimensional reconstruction and the cloudy points of C1,C2 and part of the occipital bone.Then the cloudy points were imported into the Abaqus 6.8 software to establish the occipito-atlantoaxial finite element model in normal structure.According to the established model in normal structure,the model in conditions of atlas assimilation was set by changing the model parameters.Both models of normal structure and atlas assimilation were loaded with 1.5 N · m static moment to simulate four motions of flexion,extension,lateral bending and axial rotation respectively.The movement characteristics,joint stress force and ligament deformation was analyzed.Results Under 1.5 N · m moment,in model of atlas assimilation the C1-C2 range of movement decreased from 13.55°to 11.88°in flexion,increased from 13.22°to 15.24°in extension and from 4.05°to 4.23°in lateral bending and remained unchanged in axial rotation when compared with the normal model.In flexion movement,the contact force of the atlanto-dental joint increased from 1.59 MPa to 3.28 MPa and the deflection of apical ligament,tectorial membrane and alar ligament increased 129.1％,157.6％ and 75.1％ respectively when compared with the normal model.Conclusions The normal C1-C2 motion mode is destructed in conditions of atlas assimilation,leading to the changes of the range of movement,joint stress force and the ligament deformation at C1-C2 junction.The atlantoaxial instability will likely occur in flexion motion.%目的 探讨寰枕融合下颅颈交界区的生物力学变化.方法 采用Mimics软件对一例健康成人的枕颈部CT数据进行三维重建,并获得寰椎、枢椎和部分枕骨的点云数据,导入Abaqus 6.8软件建立正常结构的枕寰枢三维有限元模型;然后改变正常模型参数建立寰枕融合模型.对正常模型和寰枕融合模型分别给予加载1.5N·m静态力矩模拟前屈、后伸、侧屈和轴向旋转4种生理运动,分析其运动特征、关节应力及韧带变形情况.结果 在1.5N·m的力矩下,寰枕融合模型与正常模型相比,寰枢间前屈运动角度从13.55°减小到11.88°,后伸角度从13.22°增加到15.24°,侧屈角度从4.05°增加到4.23°,旋转角度基本不变;寰枕融合后前屈时,寰齿关节应力从1.59 MPa增加到3.28 MPa,尖韧带、覆膜和翼状韧带变形量分别增加129.1％、157.6％和75.1％.结论 寰枕融合破坏了生理条件下的寰枢运动模式,使寰枢间的运动范围、关节应力及韧带变形发生较大变化,寰枢关节不稳定在屈曲运动时最明显.