| Objective:The computer software was used to simulate six methods to fix the Pauwels type Ⅲ femoral neck fracture model,and finite element analysis was carried out to clarify the biomechanical characteristics of each fixation methods,providing reference for clinical treatment of Pauwels type ⅢfracturesMethods:1.The CT data of right femur collected in our hospital was imported into Mimics 20.0 software for three-dimensional reconstruction,and relevant anatomical parameters of the femur were measured.Then,the reconstructed femoral model was imported into Geomagic Wrap 2017 three-dimensional model processing software for mesh detailing,bone surface defect repair,rapid smoothing,etc.Finally,the optimized model was imported into Solidworks 2017 software to establish the Pauwels Ⅲfemoral neck fracture model by CUT tool2.According to the product manual provided by instrument company and the relevant anatomical parameters of the femoral model,six methods of internal fixation model were established and loaded on the fracture model with Solidworks 2017 software,the six fixation models of femoral neck fracture including:A.Three Cannulated Compression Screws(CCS);B.Three Cannulated Compression Screws combined with transverse screw(Pauwels screw);C.Three Cannulated Compression Screws combined with 1/3 Tubular Plate(1/3TP);D.Dynamic Hip Screw(DHS)combined with De-rotational Screw(DS);E.Percutaneous Compression Plate(PCCP)of proximal femur;F.Meta-TAN intramedullary nail3.The model of Pauwels Ⅲ fracture fixed by six methods were imported into ABAQUS 6.14 software for meshing,material assignment,setting coefficient of friction and boundary conditions.The static loading force of 500 N and 2100 N(equivalent to 0.7 times and 3 times as heavy as a 70-kilogram adult)were applied to the center of femoral head,respectively.The data were recorded and analyzed:(1)Displacement distribution and maximum displacement of femur;(2)Displacement of proximal fracture fragments on Y-axis,Z-axis and X-axis,respectively;(3)The Von Mises stress distribution and peak stress of femur;(4)The Von Mises stress distribution and peak stress of internal fixation.Results:(1)The maximum femoral displacement of the six models was located at the femoral head.The maximum displacement of femur under 500N load was 2.440 mm in 3CCS,followed by 2.433 mm in 4CCS,2.425 mm in 3CCS+1/3TP,2.420 mm in PCCP,2.309 mm in Meta-TAN and 1.045 mm in DHS+DS.The maximum displacement of femur under 2100N load was 10.26 mm in 3CCS,followed by 10.23 mm in 4CCS and PCCP,10.19 mm in 3CCS+1/3TP,9.37 mm in Meta-TAN and 4.26 mm in DHS+DS(2)The displacement of proximal fracture fragment on the Y-axis direction of vertical shear force under 500N load was 0.470 mm in 3CCS,followed by 0.467 mm in 4CCS,0.453 mm in 3CCS+1/3TP,0.429 mm in Meta-TAN,10.427 mm in PCCP and 0.274 mm in DHS+DS.The displacement of proximal fracture fragment on the Y-axis direction under 2100N load was 1.973 mm in 3CCS,followed by 1.960 mm in 4CCS,1.904 mm in 3CCS+1/3TP,1.802 mm in Meta-TAN,1.792 mm in PCCP and 1.149 mm in DHS+DS(3)The displacement of proximal fracture fragment on the Z-axis direction of horizontal shear force under 500N load was 2.003 mm in 3CCS,followed by 1.993 mm in 4CCS,1.990 mm in 3CCS+1/3TP,1.975 mm in PCCP,1.882 mm in Meta-TAN and(-0.316)mm in DHS+DS.The displacement of proximal fracture fragment on the Z-axis direction under 2100N load was 8.410 mm in 3CCS,followed by 8.365 mm in 4CCS,8.359 mm in 3CCS+1/3TP,8.317 mm in PCCP,7.915 mm in Meta-TAN and(-1.348)mm in DHS+DS(4)The displacement of proximal fracture fragment on the X-axis direction of perpendicular to the fracture plane under 500N load was 0.737 mm in DHS+DS,followed by 0.604 mm in 4CCS,0.601 mm in 3CCS,0.595 mm in 3CCS+1/3TP,0.582 mm in Meta-TAN and 0.577 mm in PCCP.The displacement of proximal fracture fragment on the X-axis direction under 2100N load was 3.096 mm in DHS+DS,followed by 2.538 mm in 4CCS,2.523 mm in 3CCS,2.498 mm in 3CCS+1/3TP,2.445 mm in Meta-TAN and 2.425 mm in PCCP.(5)The peak Von Mises stresses at the proximal femur under 500N load was 33.07 MPa in 3CCS+1/3TP,followed by 17.32 MPa in DHS+DS,11.19 MPa in Meta-TAN,10.51 MPa in PCCP,10.34 MPa in 4CCS and 10.14 MPa in 3CCS.The peak Von Mises stresses at the proximal femur under 2100N load was 142.6 MPa in 3CCS+1/3TP,followed by 75.92 MPa in DHS+DS,50.12 MPa in Meta-TAN,46.57 MPa in 3CCS,45.99 MPa in PCCP and 45.15 MPa in 4CCS.(6)The Von Mises stress distribution and peak value of internal fixation models were as follows.The stress of 3CCS was concentrated on the junction of screw and fracture plane.The peak stress under 500N and 2100N load was 35.23 MPa,175.1 MPa,respectively,which located at the middle part of the lowest screw.The stress of 4CCS was concentrated on the junction of screw and fracture plane,the stress distribution was more dispersed than 3CCS.And the peak stress under 500N and 2100N load was 34.71Mpa,173.6MPa,respectively,which located at the middle part of the lowest screw.The stress of 3CCS+1/3TP was concentrated on the plate and the middle of the compression screw,the peak stress under 500N and 2100N load was 125.8 Mpa,432.3MPa,respectively,which located at the first screw hole on the plate.The stress of DHS+DS was concentrated on the middle of compression screw and dynamic compression screw.And the peak stress under 500N and 2100N load was 50.74 MPa,215.6 MPa,respectively,which located at the middle of dynamic compression screw.The stress of PCCP was concentrated on the middle part of two compression screws and the lateral plate.The peak stress under 500N and 2100N was 65.19 MPa,273.8 MPa,respectively,which located at the junction of the upper compression screw and the sleeve.The stress of Meta-TAN was concentrated on the proximal interlocking screw,and the peak stress under 500N and 2100N was 92.07MPa,434.1 MPa,respectively,which near the intramedullary nail on the square head screw.Conclusion:The whole stability of DHS+DS internal fixation models was the strongest,followed by Meta-TAN intramedullary nail,3CCS+1/3TP,PCCP,4CCS and 3CCS. |
PDF Full Text Request