Objective:To research whether the modified femoral medial support plate combined with cannulated screws for Pauwels type Ⅲ femoral neck fracture has biomechanical advantages by applying 3D finite element analysis techniques,and to provide a theoretical reference for the selection of clinical treatment and the development of a new type of femoral medial support plate.Methods:The CT data of the healthy adult femur was imported into Mimics software,and the rough 3D model of the femur was obtained through threshold segmentation,mask editing and 3D reconstruction,which was imported into Geomagic Studio software for smoothing,relaxation,noise reduction and fitting surfaces to establish a smooth 3D model of the femur with human anatomical characteristics.The model of Pauwels type Ⅲ femoral neck fracture was constructed by using SolidWords software to perform Boolean operations and other operations on the above model.,and the software was used to establish internal fixation models such as cannulated screws,common femoral medial support plate and modified femoral medial support plate,etc.By combining and assembling the internal fixation models into the femoral neck fracture model,five groups of finite element models of internal fixation for Pauwels type Ⅲ femoral neck fracture were established,including:traditional three cannulated screws fixation(Group A),common femoral medial support plate combined with three cannulated screws fixation(Group B),and modified femoral medial support plate combined with three cannulated screws fixation(Group C).After dividing the mesh,assigning material properties and setting boundary conditions to the above models,we performed analysis using Ansys software under the same boundary and loading conditions to solve and analyze the maximum displacement as well as displacement distance of the five sets of fracture internal fixation models,the peak stress of the internal fixation in different models and the peak von Mises stress of the femur in different models.Results:The most significant displacement occurred at the femoral head in all models,and the maximum displacement of the femoral head was A:1.77mm,B:1.41mm and C:1.33mm;the peak stresses of implants in different fixation models included A:380.6MPa,B:336.6MPa 和 C:325.1MPa;the peak stresses of the femoral portion in different models were A:152.3 MPa,B:131.2 MPa and C:119.6 MPa.Conclusion:This experiment shows that for Pauwels Ⅲ femoral neck fractures,better stability can be obtained by using a femoral medial support plate combined with three cannulated screws compared with three cannulated screws alone to fix the fracture,and the modified femoral medial support plate has better results compared with the common femoral medial support plate. |