Three-dimensional finite element constructing method based on medical image data LISS-DF to cure distal femur fracture

Three-dimensional finite element constructing method based on medical image data LISS-DF to cure distal femur fracture

  • CN 104,240,298 A
  • Filed: 09/10/2014
  • Published: 12/24/2014
  • Est. Priority Date: 09/10/2014
  • Status: Active Application
First Claim
Patent Images

1. treat the three-dimensional finite element model construction method of Methods for Distal Femoral Fractures based on medical image LISS-DF, it is characterized in that concrete steps are as follows:

  • (1) CT tomoscan acquisition LISS steel plate is adopted to invest the faultage image data of normal sheep femur;

    LISS steel plate is invested normal sheep lateral side of femur, and adopt spiral CT machine distally to be scanned perpendicular to the femur longitudinal axis by sheep femoral head near-end, Scan slice thickness is less than or equal to 1mm, is converted to jpeg form preservation output by scanning the standard DICOM formatted data obtained;

    (2) Three Dimensional Medical Visualization, contour feature point extract and data output;

    The CT faultage image LISS steel plate that step (1) obtains being invested normal sheep lateral side of femur imports open source software Image J (NIH, National Institutes of Health), first image conversion, image enhaucament and thresholding process are carried out respectively to sheep femur image and LISS-DF steel plate image, then the scope of sheep femur and LISS-DF steel plate objective area in image is selected respectively, finally edge extracting is carried out to the object boundary in selection area, the coordinate of the point obtained is stored respectively with txt form;

    (3) surface geometry model Primary Construction;

    In the Rhinoceros 4.0 software (U.S., Robert McNeel &

    Associates company) in the txt file of the respectively point coordinate of the complete sheep femur that obtains of steps for importing (2) and LISS-DF steel plate, selected point formation curve, set up curved surface, and derive respectively with stl file form, obtain the stl file of complete sheep femur and LISS-DF steel plate respectively;

    (4) 3D solid geometric model builds;

    In the common finite element stress and strain model software HyperMesh12.0(U.S., Altair company) in proceed as follows;

    1. generate solid geometry model based on medical image;

    the first stl file of complete sheep femur that generates of steps for importing (3), the surface mesh respectively based on sheep femur generates multiple curved surface, sets up geometric model, is stored as separately an assembly;

    Then, same operation is carried out to LISS-DF steel plate, generate corresponding geometric model, be stored as equally separately an assembly;

    2. the geometric model generated based on medical image is edited;

    normal sheep femur model is cut, generates corresponding sheep femoral fracture geometric model assembly;

    3. screw solid geometry model is generated based on principles of pedicle screws;

    the curve setting up screw surface according to physical dimension, then curved surface is generated based on curve, finally set up the 3-D geometric model of screw, according to principles of pedicle screws, generating respectively can simultaneously through the screw model component of side seam cortex inside and outside sheep femoral shaft, namely two cortex is fixed, represent with " two ", with the screw model component extending only through cortex of bone outside sheep femoral shaft, namely mono cortex is fixed, represent with " list ", each screw is stored in different assembly respectively;

    (5) three-dimensional finite element model builds;

    In software HyperMesh, choose different entities geometric model assembly on demand to assemble, generate multiple model, described model is containing whole femur model, Methods for Distal Femoral Fractures model, LISS-DF steel plate model, and the model of proximal screw various combination fixed form treatment femoral fracture, each model forms by multiple assembly, implements following operation respectively to each model;

    1. for an assembly, based on all surface forming 2D shell units;

    2. between different assembly, interface node carries out node coupling to realize the connection between assembly;

    3. tetrahedron element is created in each component internal;

    The final multiple tetrahedral finite element model generating sheep femur and proximal screw various combination fixed form treatment femoral fracture respectively.

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