髓内与髓外固定股骨颈基底部骨折的有限元分析:PFNA与FNS

Finite element analysis of intramedullary and extramedullary fixation of femoral neck base fractures:proximal femoral nail antirotation and femoral neck system

背景:股骨颈基底部骨折生物力学稳定性差,治疗方案与传统股骨颈骨折有所差别,目前临床上治疗青年股骨颈基底部骨折的手术方案仍未达成统一。目的:通过有限元分析比较股骨近端防旋髓内钉与股骨颈动力交叉钉治疗股骨颈基底部骨折的生物力学特征。方法:首先使用Mimics Medical 21.0软件提取健康青年女性志愿者右侧股骨CT数据建立初步模型;然后将该模型导入Geomagic Wrap 2021软件进一步光滑处理;利用SOLIDWORKS 2021软件建立股骨颈基底部骨折模型、股骨近端防旋髓内钉模型、股骨颈动力交叉钉模型并进行装配;最后将装配后的模型导入Workbench 2021 R1软件进行生物力学分析。结果与结论:(1)应力分布:股骨近端防旋髓内钉组股骨模型应力分布主要在骨折线附近及股骨内侧,应力峰值为151.90 MPa;股骨颈动力交叉钉组股骨模型应力分布主要在骨折线附近,应力峰值为290.74 MPa;股骨近端防旋髓内钉内固定应力主要分布在螺旋刀片及主钉近端,应力峰值为102.95 MPa;股骨颈动力交叉钉内固定应力分布主要由支撑棒向两边延伸,应力峰值为184.69 MPa;(2)总位移:股骨近端防旋髓内钉组股骨模型最大位移为4.032 3 mm,股骨颈动力交叉钉组股骨模型最大位移为4.648 9 mm,最大位移均位于股骨头;股骨近端防旋髓内钉组内固定与股骨颈动力交叉钉组内固定位移峰值分别为2.709 4 mm与3.130 3 mm,两组内固定位移均主要集中在内固定近端,逐渐向远端递减;(3)提示在股骨颈基底部骨折的模型中,无论是股骨模型还是内固定模型,股骨近端防旋髓内钉相较于股骨颈动力交叉钉应力分布更分散、应力峰值更低、股骨头位移更小,生物力学稳定性更优。

BACKGROUND:The biomechanical stability of basal femoral neck fracture is poor,and the treatment plan is different from the traditional femoral neck present,there is still no consensus on the surgical plan for the treatment of basal femoral neck fracture in young adults.OBJECTIVE:To compare the biomechanical characteristics of proximal femoral nail antirotation and femoral neck system in the treatment of basal femoral neck fractures by finite element analysis.METHODS:First,Mimics Medical 21.0 software was used to extract the right femur CT data of healthy young female volunteers to establish a preliminary model.Secondly,the model was imported into Geomagic Wrap 2021 software for further smoothing.SOLIDWORKS 2021 software was used to establish and assemble the femoral neck base fracture model,proximal femoral nail antirotation model,and femoral neck system model.Finally,the assembled model was imported into Workbench 2021 R1 software for biomechanical analysis.RESULTS AND CONCLUSION:(1)Stress distribution:the stress distribution of the proximal femoral nail antirotation group was mainly near the fracture line and the medial side of the femur,and the peak stress was 151.90 MPa.In the femoral neck system group,the stress distribution of the femoral model was mainly near the fracture line,and the peak stress was 290.74 MPa.The proximal femoral nail antirotation internal fixation stress was mainly distributed at the proximal end of the helical blade and the main nail,and the peak stress was 102.95 MPa.The stress distribution of internal fixation in femoral neck system mainly extended to both sides of the support rod,and the peak stress was 184.69 MPa.(2)Total displacement:the maximum displacement of the femoral model in the proximal femoral nail antirotation group was 4.0323 mm,and the maximum displacement of the femoral model in the femoral neck system group was 4.6489 mm.The maximum displacement was located in the femoral head.The peak displacement of internal fixation in the proximal femoral nail antirotation group and the femoral neck system group was 2.7094 mm and 3.1303 mm,respectively.The displacement of internal fixation in the two groups was mainly concentrated in the proximal end of internal fixation,and gradually decreased to the distal end.(3)It is concluded that in the femoral neck base fracture model,whether it is the femoral model or the internal fixation model,the proximal femoral nail antirotation group has more dispersed stress distribution,lower stress peak,smaller femoral head displacement,and better biomechanical stability than the femoral neck system group.