三种内固定方式修复股骨颈骨折的有限元分析

Finite element analysis of femoral neck fracture with different fixation ways

背景:有限元法在股骨颈骨折中被广泛应用,但对股骨颈骨折不同内固定方式的研究不多。目的:有限元法分析股骨颈骨折不同固定方式的生物力学特性。方法:对志愿者股骨进行CT扫描,扫描厚度为0.6 mm,从股骨大转子上方开始进行扫描,扫描数据保存为.DICOM格式。将右侧股骨近端数据导入到Mimics软件,按照PauwelsⅠ型骨折截骨。建立2枚拉力螺钉模型、全螺纹空心螺钉模型和股骨近端锁定钢板模型3种股骨颈骨折内固定模型,采用三维有限元法分析股骨颈骨折不同内固定方式模型的应力分布、应力集中部位、位移分布以及最大位移情况。结果与结论:(1)2枚拉力螺钉模型的最大应力值最大,全螺纹空心螺钉模型的最大应力值最小。2枚拉力螺钉模型、全螺纹空心螺钉模型和股骨近端锁定钢板模型的最大应力均集中在骨折的内固定端;(2)2枚拉力螺钉模型的股骨最大应力值最大,股骨近端锁定钢板模型的股骨最大应力值最小。2枚拉力螺钉模型、全螺纹空心螺钉模型和股骨近端锁定钢板模型的股骨最大应力均集中在股骨内侧小转子附近以及股骨内侧和内固定接触处;(3)2枚拉力螺钉模型的最大位移值最大,全螺纹空心螺钉模型的最大位移值最小,2枚拉力螺钉模型、全螺纹空心螺钉模型和股骨近端锁定钢板模型的最大位移均在股骨头处;(4)2枚拉力螺钉模型的内固定处最大位移值最大,全螺纹空心螺钉模型的内固定处最大位移值最小。2枚拉力螺钉模型的股骨头处最大位移值最大,全螺纹空心螺钉模型的股骨头处的最大位移值最小;(5)结果表明,对于PauwelsⅠ型骨折而言,全螺纹空心螺钉的内固定效果优于其他2种内固定方式。

BACKGROUND： Finite element method is widely used in the femoral neck fracture, but the study concerning different fixation methods of femoral neck fracture is not much. OBJECTIVE： To analyze biomechanical properties of different fixation methods for femoral neck fracture using finite element analysis. METHODS： The femur of voluntters was scanned with CT, at thickness 0.6 mm, from the site above the greater trochanter of the femur. Scanning data were saved in .DICOM format. Data of right proximal femur were imported into Mimics software. Osteotomy was performed according to Pauwels I type fracture. Models of two tensile force screws, fully threaded hollow screw and proximal femoral locking plate were established. Three-dimensional finite element method was used to analyze stress distribution, stress concentration position, displacement distribution and maximum displacement in different models of femoral neck fracture with different internal fixation methods. RESULTS AND CONCLUSION： （1） The maximum stress value of two lag screws model was biggest. The maximum stress value of fully threaded hollow screw model was minimized. The maximum stresses of two lag screws model, fully threaded hollow screw model and proximal femoral locking plate model all were concentrated in the fixed end of fractures. （2） The femoral maximum stress of two lag screws model was biggest. The femoral maximum stress value of proximal femoral locking plate model was minimized. The femoral maximum stresses of two lag screws model, fully threaded hollow screw model and proximal femoral locking plate model all were cor^centrated in the medial femoral small rotor near and medial femoral and fixation contact points. （3） The maximum displacement of two lag screws model was biggest. The maximum displacement of fully threaded hollow screw model was minimized. The maximum displacement of two lag screws model, fully threaded hollow screw model and proximal femoral locking plate model all was in the femoral head. （4） The maximum displacement value of two lag screws model fixed place was biggest. The maximum displacement value of fully threaded hollow screw model fixed place was minimized. The maximum displacement value of two lag screws model was biggest at femoral head. The maximum displacement value of fully threaded hollow screw model was minimized at femoral head. （5） Results showed that the treatment effect of fully threaded hollow screw on Pauwels I fractures was better than other two fixation methods.