不同运动步态下锁定加压钢板固定胫骨干骨折的有限元分析

背景：目前有限元分析广泛应用于人体骨折内固定模型的力学分析,但大多研究局限于静态下,动态下的骨折模型有限元分析尚未见报道。 目的：通过三维有限元分析来探讨锁定加压钢板固定胫骨干不同类型骨折在不同运动步态下的应力分布情况。 方法：利用CT扫描获得正常成人胫腓骨及足部的薄层扫描图像;运用相关软件建立其三维模型,在此模型上模拟出胫骨中段横行、斜行、粉碎性、螺旋形4种类型骨折,并与锁定钢板进行装配生成实验模型,各组模型加载相同的轴向压缩载荷600 N。通过有限元分析软件Ansys 12.0分别测定各组模型在落地相、中立相、离地相三种步态下的应力分布情况。 结果与结论：在步态下,胫骨在骨折各组中的应力分布由小到大均为：落地相<中立相<离地相。锁定钢板在胫骨中段横行、斜行、粉碎性骨折中的应力分布由小到大均为：中立相<落地相<离地相;在胫骨中段螺旋形骨折中应力分布由小到大为：离地相<中立相<落地相;提示在运动步态中,钢板和胫骨均在离地相受力最大。钢板的应力集中在中间或边缘;而胫骨的应力分布在骨折线以上靠近近端,骨折线以下靠近骨折线。就胫骨整体而言,呈现两端集中,中间分散的状态。

Finite element analysis of different tibial shaft fracture fixed by Locking compression plate under different movement gait

BACKGROUND:In recent years, the finite element analysis has been widely used in the mechanical analysis of human fracture internal fixation model, but studies on the finite element analysis are often under the static state, the reports on the finite element analysis under physiological state are few. OBJECTIVE:To explore the stress distribution of different tibial shaft fractures fixed by locking compression plate under different movement gaits through three-dimensional finite element analysis. METHODS:CT scan was performed to obtain the thin layer scanning image of normal adult tibiofibula and foot; three-dimensional models were established by relative software, and then transverse, oblique, spiral, comminuted fractures were imitated on the models and combined with the locking plate to generate the experimental models. The models in each group were subjected to the same axial compression load of 600 N. The stress distribution of the models under heel-strike phase, the midstance phase and the push-off phase was analyzed with software Ansys 12.0. RESULTS AND CONCLUSION:Under this experimental model, the stress distribution of tibia in four groups from small to large was heel-strike phase < midstance phase < push-off phase; the stress distribution of locking compression plate in the tibial transverse, oblique and comminuted fractures from small to large was the midstance phase < the heel-strike phase < the push-off phase; stress distribution of locking compression plate in the tibial spiral fracture group from small to large was the push-off phase < the midstance phase < the heel-strike phase. Under the physiological state, the largest stress of the locking compression plate and the tibia were in the push-off phase. The stress distribution of the locking compression plate focused on the middle or edge of itself; while the stress distribution of the tibia focused on the proximal end above the fracture line and on the end under the fracture line. From the overall of the tibia, the stress distribution focused on both ends, and scattered on the middle.