外置锁定钢板固定42A2型胫骨中段不同角度斜行骨折的Mises应力分析

Mises stress analysis of 42A2 type tibial mid segment oblique fracture fixed with external locking plate at different angles

目的建立锁定钢板固定42A2型胫骨中段斜行骨折不同骨折线方向以及骨折线与胫骨长轴不同夹角的三维模型,采用有限元分析的方法对锁定钢板、螺钉及胫骨的生物力学进行计算分析,为临床的应用提供理论依据。方法选取一名健康成人志愿者,25岁,男性,身高173 cm,体重69.5 kg,对左侧胫骨进行CT扫描,获取相关数据建立锁定钢板固定42A2型胫骨中段斜行不同骨折线方向及骨折线与胫骨长轴不同夹角的骨折模型,并分别采用8孔纯钛接骨板进行固定。比较不同角度骨折模型的锁定钢板、螺钉及胫骨的Mises应力变化。结果在骨折线自外下向内上即左斜方向42A2型骨折的情况下,胫骨Mises应力最大值为114 MPa,螺钉Mises应力最大值为279.8 MPa,锁定钢板Mises应力最大值为302.4 MPa;而骨折线自内下向外上即右斜方向骨折的情况下,胫骨Mises应力最大值为93.41 MPa,螺钉Mises应力最大值为353.4 MPa,锁定钢板Mises应力最大值为411.8 MPa。结论左斜、右斜两种方向斜行骨折,应力最大值均为:锁定钢板>螺钉>胫骨;在该锁定钢板位置固定的情况下,锁定钢板、螺钉最大应力值均是右斜骨折>左斜骨折;且最大应力值均随角度增大而增大。

Objective To establish a three-dimensional model of locking plate fixation for 42A2 type oblique tibial fractures with different fracture line directions and different angles between the fracture line and the long axis of the tibia.Finite element analysis was used to calculate and analyze the biomechanics of locking plate,screw,and tibia,providing theoretical basis for clinical application.Methods A healthy adult volunteer,25 years old,male,with a height of 173 cm and a weight of 69.5 kg,was selected to perform computed tomography(CT)scans on the left tibia.Relevant data were obtained to establish a locking steel plate fixation model for 42A2 type tibia with different oblique fracture line directions and different angles between the fracture line and the long axis of the tibia.Eight hole pure titanium plates were used for fixation,respectively.We compared the Mises stress changes of locking plates,screws,and tibia in different angle fracture models.Results In the case of a 42A2 type fracture in the left oblique direction with a fracture line from outside to inside,the maximum Mises stress in the tibia was 114 MPa,the maximum Mises stress in the screw was 279.8 MPa,and the maximum Mises stress in the locking steel plate was 302.4 MPa;In the case of a 42A2 type fracture in the right oblique fracture with a fracture line from the bottom to the top,the maximum Mises stress of the tibia was 93.41MPa,the maximum Mises stress of the screw was 353.4 MPa,and the maximum Mises stress of the locking steel plate was 411.8 MPa.Conclusions Regardless of the oblique fractures in both left and right directions,the maximum stress values are:locking plate>screw>tibia;When the position of the locking steel plate is fixed,the maximum stress values of the locking steel plate and screw are both right oblique fracture>left oblique fracture;And the maximum stress values all increase with the increase of angle.