PFNAⅡ与LCP DHS Blade治疗股骨转子间骨折的生物力学研究

Study on biomechanics of PFNA Ⅱ and LCP DHS Blade in treating intertrochanteric fractures

目的通过在计算机仿真人体动力学条件下进行有限元分析,探讨股骨近端抗旋髓内钉(PFNAⅡ)与带螺旋刀片的锁定加压钢板与动力髋螺钉(LCP DHS Blade)治疗稳定型股骨转子间骨折(AO分型31-A1)的生物力学情况,为术后康复提供理论依据。方法选取2017年4月该院右股骨转子间骨折患者1例,采用Simpleware软件建立完整股骨的三维几何模型,按照AO分型31-A1的骨折形态对股骨模型进行切割,在Geomagic Studio软件中分别与PFNAⅡ和LCP DHS Blade的三维几何模型进行装配,并在HyperMesh软件中对模型进行网格划分,形成网格模型后替换Anybody软件中的正常人体股骨模型,进行人体动力学仿真计算,施加的载荷为步态过程中右侧股骨所受到的关节力和肌肉力。将通过Anybody及HyperMesh生成的网格模型导入Abaqus软件中,分析步态过程中股骨和植入物的应力分布情况。结果 (1)在正常步态的载荷下,使用PFNAⅡ和LCP DHS Blade固定的稳定型股骨转子间复合模型均没有出现明显应力集中的区域。(2)在一个步态周期中,2种植入物的应力均呈现双波峰分布,第一个波峰出现在右下肢支撑相中期,第二个波峰出现在右下肢支撑相末期,但都没有达到材料的屈服强度。(3)2种植入物对比,PFNAⅡ承担的应力较小,且分布较均匀,而LCP DHS Blade承担的应力较大,并可见应力集中于螺旋刀片的纤细部分。结论对于稳定型股骨转子间骨折(AO分型31-A1),不论采用PFNAⅡ还是LCP DHS Blade进行固定,手术侧肢体都可以完全负重行走,而PFNAⅡ固定具有一定的生物力学优势。

Objective To investigate the biomechanical situation of proximal femoral nail antirotation 11 （PFNAⅡ ） and locking compression plate dynamic hip system blade （LCP DHS Blade） in the treatment of stable intertrochanteric fractures （AO type 31-A1） by conducting the finite element analysis under the condition of computer simulation human body biomechanics so as to provide a theoretic basis for postoperative rehabilitation.Methods 1 case of right femoral intertrochanteric fracture in the hospital in April 2017 was selected.The three-dimensional geometric model of the complete femur was established by the Simpleware software.The femur model was incised according to the shape of fracture （AO type 31-A1） and assembled with PFNAⅡ and LCP DHS Blade three-dimensional geometric models in the Geomagic Studio software, then the grid generation was performed on the model in HyperMesh software, after rotating the grid model, which substituted the nomml human body femoral model in Anybody software for conducting the human body simulation calculation.The exerted load was the joint force and muscle force suffered by the right femur during gait process.Then the grid model generated by Anybody and HyperMesh was introduced into the Abaqus software. The stress distribution situation of femur and implantation material during gait process was analyzed.Results （ 1 ） Under the load of normal gait, PFNAⅡ and LCP DHS Blade fixed stable femoral intertrochanteric complex models did not appear obvious stress concentration area. （2） In a gait cycle, both the stress of two kinds of implantation materials presented double peak distribution, the first peak appeared in the middle of the right leg stand phase, the second peak appeared in the end of right leg stand phase, but they did not reach the yield strength of the materials. （3） In the comparison of the two kinds of implantation materials, PFNAⅡ beared smaller stress and the distribution of stress was unifore1, while LCP DHS Blade beared larger stress, moreover it was seen that the stress was concentrated in the thin part of the spiral blade. Conclusion For stable intertrochanteric fractures （AO type 31-A1） , whether adopting PFNAⅡ or LCP DHS Blade fixation, the leg on the operation side can walk with fully weight-bearing, in which the PFNAⅡ fixation has a certain biomechanical advantages.