拇外翻足三维有限元模型构建及其第1、2跖列生物力学分析

Construction of Three-Dimensional Finite Element Model of Hallux Valgus Foot and its Biomechanical Analysis of the First and Second Rays

目的建立拇外翻足有限元模型,研究不同拉力下第1、2跖列的应力及位移变化情况。方法将采集的拇外翻病人足部CT图像导入Mimics软件,重建足部三维骨骼模型;利用3-matic软件对重建模型进行网格划分与体网格生成;将优化处理过的模型导入ANSYS中进行有限元分析,通过改变拉力大小、方向验证拉力与第1、2跖列的应力、位移之间的关系。结果对第1近节趾骨施加不同大小、方向的拉力,当力小于12 N时,随着拉力的增加,第1趾骨位移变化较为明显,拉力每增大2 N,位移约增加1 mm;当力大于12 N时,随着拉力的增加,第1趾骨应力不断增加,而位移只发生微小变化;而当力保持12 N不变,以15°间隔改变力的方向时,第1、2跖列的应力大小及其分布随方向的变化而改变,同时位移也会产生相应的变化,且当力的方向与第2趾骨方向越趋于垂直时,第1趾骨产生的位移越大。结论有限元分析技术可以形象、准确地分析第1、2跖列在不同拉力下的应力及位移变化情况,为拇外翻矫形器的设计奠定基础。

Objective To establish a finite element model of the hallux valgus foot and study the stress and displacement changes in the first and second rays of the hallux valgus under different tensile forces.Methods Foot CT images of a patient with hallux valgus were imported into Mimics to reconstruct a three-dimensional(3D)skeletal model of the foot.The 3-matic software was used to mesh the reconstructed model and generate the volume mesh.The optimized model was imported into ANSYS for finite element analysis.The relationship between the tensile forces and the stress/displacement of the first and second rays of the hallux valgus was verified by changing the size and direction of the tensile forces.Results Tensile forces of different magnitudes and directions were applied to the first proximal phalanx.When the force was less than 12 N,with an increase in tension,the displacement of the first phalange changed more significantly.For every 2 N increase in tension,the displacement increased by approximately 1 mm.When the force was greater than 12 N,with an increase in tension,the stress on the first phalange increased,whereas the displacement only changed slightly.In addition,when the magnitude of the force remained unchanged at 12 N and the direction of the force changed at intervals of 15°,the stress and stress distributions of the first and second rays changed with direction,and the displacement also changed accordingly.When the direction of the force was perpendicular to that of the second phalanx,the displacement of the first phalanx increased.Conclusions Finite element analysis technology can vividly and accurately analyze the stress and displacement changes of the first and second rays of hallux valgus under different tensile forces,and it lays a foundation for the design of hallux valgus orthoses.