动力加压钢板固定肱骨中下段螺旋形骨折的有限元分析

Finite element analysis of dynamic compression plates for the treatment of spiral fracture at the middle,distal end of humerus

[目的]通过三维有限元法对动力加压钢板(DCP)置于前外侧和后侧,使用和不使用拉力螺钉固定肱骨中下段螺旋形骨折进行生物力学比较,为临床应用提供理论参考。[方法]分别建立前外侧动力加压钢板(A1)、后侧动力加压钢板(B1)、前外侧拉力螺钉加动力加压钢板(A2)、后侧拉力螺钉加动力加压钢板(B2)固定肱骨中下段螺旋形骨折的有限元模型。应用有限元分析法在相同加载和约束条件下模拟轴向压缩、逆时针扭转和三点弯曲三种工况,评价各组内固定最大应力、骨折块最大位移、骨折断端应力分布和最大位移等指标。[结果]在压缩和弯曲工况下,前外侧较后侧内固定物最大应力及骨折块最大位移较大,扭转工况则相反。使用较不使用拉力螺钉在三种工况内固定物的最大应力值小,且分布均匀。压缩工况下,使用拉力螺钉较不使用骨折块的最大位移值较大,弯曲和扭转工况,最大位移值则较小。各组模型骨折断端应力分布基本相似,加用拉力螺钉可减小骨折面最大位移。[结论]动力加压钢板置于后侧在轴向压缩和弯曲时稳定性更强,置于前外侧抗扭转能力更具优势;使用拉力螺钉更有利于骨折愈合,可增强扭转和弯曲时的稳定性,但会降低压缩时的稳定性。

[Objective]This study aimed to explore and compare the biomechanical properties dynamic compression plates for the treatment of spiral fracture at the middle,distal end of humerus through finite element analysis,therefore to provide theoretic reference for clinic application. [Method]3D FE models of the spiral fracture at the middle,distal end of humerus fixed with dynamic compression plates in anterolateral and posterior approaches using or not using lag screws were established. Axial compression,bending and anticlockwise torsion were simulated. The von- Mises stress and total deformation distribution of humerus,internal fixities and the fracture end were studied. [Result]Under compression and bending loadings,the maximum stress of the anterolateral approach and the maximum deformation of humerus were larger than those in posterior approach,while opposite results were obtained under torsion loading. Under all three loadings,the maximum stress of internal fixities of the groups using lag screws was smaller. Under the bending and torsion loadings,the maximum deformation of the groups using lag screws was smaller,while opposite results were obtained under torsion loading. The stress distribution of fracture ends of four groups was similar,and the groups using lag screws were with smaller maximum deformation of fracture ends. [Conclusion]For spiral fracture at the middle,distal end of humerus fixed with dynamic compression plates,posterior approach is more stable than anterolateral approach under compression and bending loadings,while contrary results were obtained under torsion loading. Lag screws usage is better for fracture healing,and it is more stable than without lag screws under bending and torsion loadings,while opposite results were obtained under compression loading.