有限元分析LISS-DF治疗股骨远端骨折近端螺钉单双皮质不同组合固定方式的应力分布

背景:如何确定LISS-DF近端螺钉单双皮质合理搭配的固定方式,以便达到骨折两端螺钉固定强度的相对平衡,降低锁定钢板、螺钉和骨皮质之间的剪切应力,避免螺钉的应力集中,产生更有效的治疗结果是避免内固定失败的关键。目的:对LISS-DF钢板治疗股骨远端骨折近端螺钉单双皮质不同组合的固定方式进行有限元分析及力学评价。方法:在ANSYS9.0软件中建立LISS-DF钢板固定股骨远端骨折(AO/OTA33-A3型)的实体模型和有限元模型。在近端螺钉单、双皮质不同组合固定方式下,通过模拟生理应力做轴向加压、扭转实验,同时评估近端螺钉的应力变化。结果与结论:在16种不同组合方式中,当近端螺钉组合为1,3单2,4双皮质固定时,近端4枚螺钉的应力均值最小为24.21975N,同时剪切应力均值亦为最小,位移变化与其他组合固定方式相当且均较小。提示近端螺钉靠近骨折端处双皮质固定,其余螺钉依次单双皮质交替固定时,LISS-DF系统应力分散,抗拔出和抗扭转效果好,从而减少钢板螺钉早期的松动脱落。

Stress distribution of proximal screw fixation of single and double cortex different combinations in less invasive stabilization system-distal femur treatment: A finite element analysis

BACKGROUND: How to determine the less invasive stabilization system-distal femur (LISS-DF) proximal cortical screw fixation of single and double cortex in a reasonable collocation way to reach a relative balance of fixation strength in screw at both ends of fractures, decrease shear stress between the screws and cortical bone, avoid stress concentration of the screws, receive a better clinical effect. All of those are the key to prevent internal fixation failure. OBJECTIVE: To observe the LISS-DF treatment of distal femoral fractures proximal cortex of different combinations of single and double screw fixation by finite element analysis and mechanical evaluation. METHODS: Solid model and finite element model of the LISS-DF plate for distal femoral fractures (AO/OTA33-A3 type) were builded in ANSYS9.0 software. Proximal screws in single and double cortex fixation of different combinations, axial compression torsion test were detected through the simulation of physiological stress, and stress changes the proximal screw was evaluate. RESULTS AND CONCLUSION: In 16 different combinations, when the combination of proximal screw 1, 3 single and 2, 4 double fixed cortex, mean stress of the proximal 4 screws was minimum (24.219 75 N), and the mean shear stress was also the minimum, displacement was close to other fixation and all were tiny. Proximal screw near the end of femoral fractures, and the remaining cortical screws followed by alternating single and double fixed, the LISS-DF system stress is decentralized, effect of anti-pull and anti-reverse is well, thereby the early loosening of plate and screw off is reduced.