改良螺纹克氏针内固定治疗尺骨冠突骨折的三维有限元分析

Three-dimensional finite element analysis of the treatment of ulnar coronoid process fracture with modified threaded Kirschner wire

背景:对于肘关节不稳定的尺骨冠突骨折患者,应该进行有效的手术固定,当冠突骨折块较大时可选择的内固定材料较多,如微型钢板、钢丝、螺钉、锚钉等,但当骨折块较小时,选择合适的内固定装置是目前面临的一个棘手问题。目的:利用有限元分析法探讨改良螺纹克氏针内固定治疗尺骨冠突骨折的稳定性。方法:采用128排薄层CT对1名健康男性志愿者肘部进行扫描,运用Mimics 21.0等软件建立尺骨冠突Regan-MorreyⅡ型骨折模型,运用Unigraphics NX 10.0软件建立普通克氏针(1.2 mm)及改良螺纹克氏针(1.2 mm)模型。将上述3种模型数据导入ANSYS Workbench软件并生成尺骨冠突Regan-MorreyⅡ型骨折普通克氏针内固定模型(普通针组)和尺骨冠突Regan-MorreyⅡ型骨折螺纹克氏针内固定模型(螺纹针组),两组模型均进行抗拔出、抗水平位移及抗旋转位移模拟实验,记录骨折块位移及应力变化,绘制变化曲线图并得出Mises应力云图。结果与结论:①抗拔出模拟实验:普通针组骨折块的最大位移为3.96 mm、最大应力为93.2 N,螺纹针组骨折块的最大位移为0.20 mm、最大应力为177.6 N,螺纹针组应力分布较普通针组略有集中;②抗水平位移模拟实验:普通针组骨折块的最大位移为0.55 mm、最大应力为199.2 N,螺纹针组骨折块的最大位移为0.05 mm、最大应力为573.7 N,螺纹针组应力分布较普通针组略有集中;③抗旋转位移模拟实验:普通针组骨折块的最大位移为3.75 mm、最大应力为332.2 N,螺纹针组骨折块的最大位移为0.25 mm、最大应力为225.6 N,螺纹针组应力分布较普通针组略有集中;④结果表明:应用改良螺纹克氏针内固定治疗尺骨冠突骨折块具有更好的稳定性。

BACKGROUND:Effective surgical fixation should be performed for patients with ulnar coronoid fractures with unstable elbow joint.When the coronoid fracture fragment is large,there are more internal fixation materials,such as microplates,steel wires,screws,and anchors.However,when the fracture fragment is small,choosing the appropriate internal fixation device is a difficult problem.OBJECTIVE:To explore the stability of modified threaded Kirschner wire in the treatment of ulnar coronoid process fracture using finite element analysis.METHODS:Thin layer 128-row CT was applied to scan the elbow of one healthy male volunteer.Ulnar coronoid process Regan-MorreyⅡtype fracture model was established using the software such as Mimics 21.0.The models of ordinary Kirschner wire(1.2 mm)and modified threaded Kirschner wire(1.2 mm)were established by Unigraphics NX 10.0 software.The above three kinds of model data were imported into ANSYS Workbench software to generate the ulnar coronoid process Regan-MorreyⅡtype fracture model of ordinary Kirschner wire fixation(ordinary wire group)and the ulnar coronoid process Regan-MorreyⅡtype fracture model of modified threaded Kirschner wire fixation(threaded wire group).The anti-pull-out simulation test,anti-horizontal displacement simulation test and anti-rotational displacement simulation test were carried out for both groups of models.The displacement and stress changes of fracture blocks were recorded,and the variation curves were plotted and Mises stress nephogram was obtained.RESULTS AND CONCLUSION:(1)In the anti-pull-out simulation test,the maximum displacement and the maximum stress of the ordinary wire group were 3.96 mm and 93.2 N,respectively.The maximum displacement and the maximum stress of threaded wire group were 0.20 mm and 177.6 N,respectively.The stress distribution of the threaded wire group was slightly more concentrated than that of the ordinary wire group.(2)In the anti-horizontal displacement simulation test,the maximum displacement and the maximum stress of the ordinary wire group were 0.55 mm and 199.2 N,respectively.The maximum displacement and maximum stress of the threaded wire group were 0.05 mm and 573.7 N,respectively.The stress distribution of the threaded wire group was slightly more concentrated than that of the ordinary wire group.(3)In the anti-rotational displacement simulation test,the maximum displacement and the maximum stress of the ordinary wire group were 3.75 mm and 332.2 N,respectively.The maximum displacement and the maximum stress of the threaded wire group were 0.25 mm and 225.6 N,respectively.The stress distribution of the threaded wire group was slightly more concentrated than that of the ordinary wire group.(4)The experiment proves that the modified threaded Kirschner wire has better stability in fixation of ulnar coronoid process fracture.