Geometrically accurate and anatomically correct threedimensional geometric
models of human bones or bone sections are essential for successful
pre-operative planning in orthopedic surgery. For such purposes, 3D polygonal
models of bones are usually created based on Computer Tomography (CT) or
Magnetic Resonance Imaging (MRI) data. In cases where there is no CT or MRI
scan, or part of bone is missing, such three-dimensional polygonal models are
difficult to create. In these situations predictive bone models are commonly
used. In this paper, the authors describe the developed a software system for
creation of Human Bones Customized Polygonal models (HBCP) which is based on
the use of the predictive parametric bone model. The software system enables
creation of patient-specific polygonal models of bones, by using only a
limited number of parameter values. Parameter values can be acquired from
volumetric medical imaging methods (CT, MRI), or from two-dimensional imaging
methods (i.e. Xray). This paper introduces the new approach to the process of
creation of human bones geometrical models which are based on the anatomical
landmark points. Testing of the HBCP for the cases of femur bone samples has
shown that created bone and bone region models are characterized by a good
level of anatomical and morphometric accuracy compared to the results
presented in similar researches.
A finite element (FE) model for analysis of tire rolling on the drum, based on a specially developed CAD model, is presented in the paper. All the changes performed on the geometry of CAD model are automatically propagated to FE model. This makes the FE model very suitable for parametric studies, which help tire designer to quickly find the optimal values of tire design parameters. In this way the tire design process is shortened and the quality of resulting tires improved. The results of finite element analyses conducted on the model have directly been compared to experimental ones, confirming model validity. Equipment and methods used for experimental determination of braking and cornering characteristics of the tire as well as for experimental determination of friction coefficient of tire tread have been shown. The difference between experimental and numerical results was smaller after the calibration of friction coefficient had been performed and in such a way a further improvement of the existing model was achieved.
According to the observed inaccuracy of indirect measurement, we recommended the use of a correction factor for calculation of both Gn-IdD and Gn-CoD real vales, in defining of parametric model of the "standard mandible" based on indirect morphometry on 2D reconstructions of mandibular MSCT scans. Additional studies with larger number of specimens and quantification of anatomical variations regarding to sex, age, dentition status and ethnic origin, additionally should increase measurement accuracy and consequently reliability of future parametric model of the human mandible.
The paper presents a case where an implant for a part of the sternum (with costal cartilages) affected by cancer was created and implanted by using the specific reverse modeling method and solid free-form fabrication. The method provides surgeons with a fast and reliable tool for tissue engineering and implantation and therefore improves the quality of life for patients. Digital images of healthy sternum samples were used to develop a reverse modeling algorithm that semi-automatically generates a necessary and sufficient simplification of the tissue geometry to be fabricated in an inexpensive and applicable manner. In this particular case, the redesign of the missing part of the sternum in CAD software took three designer-hours. At the same time, the suitable simplification of the geometry affects the fabrication of simpler and less expensive casting molds. Furthermore, the core of the developed algorithm for the reverse modeling of sternum can be applied in the reverse modeling improvement of other tile (or plate-like) bones.
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