股骨颈系统治疗成人PauwelsⅢ型股骨颈骨折的有限元分析

Finite element analysis of femoral neck system for adult PauwelsⅢfemoral neck fracture

背景:对于PauwelsⅢ型股骨颈骨折,内固定方式选择尚未达成共识。目的:采用三维有限元方法分析股骨颈系统治疗成人PauwelsⅢ型股骨颈骨折的生物力学特征,为其在临床实践中的应用提供理论依据。方法:利用志愿者CT影像资料建立PauwelsⅢ型股骨颈骨折模型,同时建立4种内固定模型:4枚空心拉力螺钉、双平面双支撑螺钉固定、经皮加压钢板、股骨颈系统。将内固定模型与股骨模型按照临床常用固定方法进行装配,最后使用Ansys软件进行加载、计算,分析各模型股骨与内固定的应力分布、应力峰值和最大位移。结果与结论:①股骨近端骨折块应力主要分布在股骨颈下方靠近股骨距附近,4枚空心拉力螺钉组应力峰值最大,股骨颈系统组最小;②近端骨折块位移峰值4枚空心拉力螺钉组最大,股骨颈系统组最小;③股骨位移峰值经皮加压钢板组位移峰值最大,双平面双支撑螺钉固定组最小;④内固定应力主要分布在骨折面附近内固定装置表面,经皮加压钢板组应力峰值最大,4枚空心拉力螺钉组最小;⑤内固定位移峰值经皮加压钢板组位移峰值最大,双平面双支撑螺钉固定组最小;⑥结果表明,相较于其他3组,股骨颈系统显示出更小的近端骨折块应力及位移,内固定应力分布更均匀、分散,力的传导性更好。此外,双平面双支撑螺钉内固定位移峰值最小,但其内固定应力大于股骨颈系统,且应力相对集中,这可能会导致螺钉断裂。结果说明,股骨颈系统生物力学稳定性更优,可以为骨折愈合创造更好的力学环境。

BACKGROUND:There is no consensus on the choice of internal fixation for Pauwels typeⅢfemoral neck fractures.OBJECTIVE:To analyze biomechanical characteristics of femoral neck system in the treatment of adult Pauwels typeⅢfemoral neck fracture by threedimensional finite element method,providing theoretical basis for its application in clinical practice.METHODS:The model of Pauwels typeⅢfemoral neck fracture was established by using CT images of volunteers,and four internal fixation models were established:four cannulated compression screws,biplane double-supported screw fixation,percutaneous compression plate,and femoral neck system.The internal fixation model and femur model were assembled according to common clinical fixation methods.Finally,Ansys software was used for loading and calculation to analyze the stress distribution,stress peak value,and maximum displacement of femur and internal fixation in each model.RESULTS AND CONCLUSION:(1)The stress of the proximal femoral fracture is mainly distributed in the lower part of the femoral neck near the talus femur.The stress peak of four-cannulated compression screw group was the largest and that of femoral neck system group was the smallest.(2)The displacement peak of four-cannulated compression screw group was the largest and that of femoral neck system group was the smallest.(3)The displacement peak of percutaneous compression plate group was the largest and that of biplane double-supported screw fixation group was the smallest.(4)The internal fixation stress was mainly distributed on the surface of the internal fixation device near the fracture surface.The stress peak of percutaneous compression plate group was the largest and that of four-cannulated compression screw group was the smallest.(5)The displacement peak value of percutaneous compression plate group was the largest and that of biplane double-supported screw fixation group was the smallest.(6)Above results concluded that compared with other three groups,the femoral neck system showed smaller proximal fracture mass stress and displacement,more uniform and dispersed stress distribution,and better force conductivity.In addition,biplane double-supported screw fixation internal fixation has the smallest displacement peak,but the internal fixation stress is greater than femoral neck system,and the stress is relatively concentrated,which may lead to screw fracture.The experimental results show that the femoral neck system has better biomechanical stability and can create a better mechanical environment for fracture healing.