股骨转子间骨折不同固定方式影响股骨近端应力的有限元分析

Different fixations for intertrochanteric fracture affect proximal femur stress: a finite element analysis

背景:股骨转子间骨折髓内与髓外固定方式的力学特点一直是有限元研究的热点,但国内对于股骨近端张力及压力侧对比研究较少。课题组研究发现,股骨近端应力带的分布是研究骨折及内固定设计与使用的重要依据。目的:探讨股骨转子间骨折采用髓内及髓外固定对股骨近端压力侧及张力侧的应力影响。方法:通过对志愿者股骨CT扫描,Mimics建模,模拟EvansⅠ型股骨转子间骨折,分别采用股骨近端防旋髓内钉及动力髋螺钉固定,模拟双下肢负重时股骨近端的应力状况,运用Abaqus 6.13有限元分析软件进行计算,并对不同固定方式下股骨近端、固定器械压力侧及张力侧的应力进行分析。结果与结论:(1)股骨近端防旋髓内钉组压力侧及张力侧的应力均小于动力髋螺钉组,股骨近端防旋髓内钉固定后股骨近端的应力更加趋向于生理状态;(2)结果提示,股骨转子间骨折髓内固定较髓外固定具有更好的力学优势,髓内固定有利于股骨近端压力侧及张力侧的保护。

BACKGROUND：The mechanical characteristics of intramedul ary and intramedul ary fixations for treating intertrochanteric fracture were hot research of finite element, but there was few comparative research on tension side and pressure side of proximal femur. In our study, we found that the distribution of the stress zone was important indication to researches on intertrochanteric fracture and internal fixation design. OBJECTIVE：To explore the effects of intramedul ary and extramedul ary fixations for treating intertrochanteric fracture on pressure side and tensile side of proximal femur. METHODS：CT scan and Mimics modeling of volunteer’s femur were conducted, and the model Evans type I intertrochanteric fracture was constructed and treated with proximal femoral nail antirotation and dynamic hip screw respectively. The stress condition of proximal femur in weight status was simulated. The Abaqus 6.13 was used for finite element analysis, and the tension side and pressure side of proximal femur in both fixations were also analyzed. RESULTS AND CONCLUSION：（1） The stresses of compressive side and tensile side in proximal femoral nail antirotation group were both less than that in dynamic hip screw group. The stress of proximal femur in proximal femoral nail antirotation group was more similar to that in physiological status. （2） These findings verified that for treating intertrochanteric fracture, intramedul ary fixation exerted better mechanical behavior than extramedul ary fixation. The protection of compressive side and tensile side of proximal femur had achieved by intramedul ary fixation.