天鹅型记忆接骨器治疗肱骨骨折和骨不连的三维有限元分析

目的：研究天鹅型记忆接骨器（SMC）治疗骨折和骨不连及其产生的动态记忆应力促进骨愈合的生物学基础。方法：利用计算机仿真三维有限元技术，对SMC固定肱骨的生物力学行为进行模拟，接骨器有限元模型共划分了3487个单元，节点数为5397，单元采用20节点四面体三维砖块单元；肱骨有限元模型共划分5783个单元，节点数9863，单元采用10节点四面体三维单元，结果：接骨器固定肱骨后其内表面受拉力，外表面受压力，变形最大的加压部第一结构主应力最大值分别为224．5MPa和－34MPa，远小于其极限应力与疲劳极；其维持轴向的动态记忆持骨力为125．05N，纵向动态记忆加压力196N，被固定肱骨应力分布均匀，各节点所受应力主要为正应力。结论：SMC有良好的耐疲劳与重复使用性，其固定后产的动态记忆加压应力场，有利于固定肱骨的稳定并促进骨愈合。

Three-dimensional element analysis of swan-like memory compressive connector for treating fractures and nonunion of humerus

Objective:To study the biomechanical basis of swan like memory compressive connector (SMC) for treating fractures and nonunions, and the facilitating effects of dynamic memorial stress of SMC for bone healing. Methods:By computer emulation and three dimensional (3D) finite element analysis, the biomechanical behavior of humeral type connector for fixing humerus was emulated and analyzed. The finite element model of humeral type connector was divided into 3 487 units. The number of nodes was 5 397. The element was a unit with 20 nodes, 4 faces. The finite element model of humerus was divided into 5 783 units, the number of nodes was 9 863. And the finite element was a 3D unit with 10 nodes, 4 faces.Results:When the connector fixated humerus, it came in for tension stress in its inner surface, and compressing stress in its outer surface. The maximum first structural major stress of metamorphosed compressive part was 224.5 MPa and -34 MPa, far less than its utmost stress and fatigue limit. The initiative memorial bone holding force for maintaining axial stability was 125.05 N, and the longitudinal initiative memorial compression force was 196 N. The stress distribution in fixed humerus was even, the stress in most nodes was positive stress. Conclusion:The SMC has good anti fatigue and reuse characters. The dynamic memorial compressive stress field is good for the stability of fixation and enhancement of bone healing.