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MKP analýza nerovnoměrné cementové vrstvy acetabulární komponenty totální kyčelní endoprotézy
Vyčichl, Jan ; Kunecký, Jiří ; Kytýř, Daniel ; Jírová, Jitka
The article deals with FE contact analysis of interaction between pelvic bone and cemented acetabular component with imperfection in cement layer. Imperfection is thinking as non-uniform cement layer of double types. First type is attenuate cement layer and second type is extrude cement layer with contact between polyethylene cup and pelvic bone. For all this cases there were created contact FE models with defination boundary contitions and loads. This models were used to ascertain the contact stress conditions in the underlying subchondral bone. Results were compared with ideal position of acetabular component in the pelvic bone.
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Creation of the helmet model from the 3D scanning
Micka, Michal ; Vyčichl, J.
Contribution deals with the preparation of the numerical model of the cycling protective helmet for calculation with the computer programme ANSYS. The helmet was scanning by the hand scanner. After evaluation of the pictures of the helmet surface are at disposal the graphic output files in the format IGES and STL . To unloaded them and for the creation of the numerical geometrical model in ANSYS the modification of the model was performed in two ways. First the input file is edited from the format IGES and second it is the creation of the helmet outside surface from triangles inscribed into the surface of the model in format STL.
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Vliv svalové dysbalance na migraci kyčelního implantátu
Kytýř, Daniel ; Jírová, Jitka ; Vyčichl, Jan ; Jíra, J.
In general all orthopaedic operations may cause the change of muscle balance. This dysbalance various not only range of movement but also the loading vector during the movement. In case of hemiarthroplasty when the new joint is created by femoral replacement and intact acetabulum could be the dysbalance very dangerous. Migration of the implant head after hemiarthoplasty is the problem which observed to nearly at all patients. Muscle dysbalance and shape of acetabulum are the two main problems solved by numerical analysis of hip joint FE model.
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Problematika endoprotéz kyčelních kloubů poškozených pády a dopravními nehodami
Kytýř, Daniel ; Jírová, Jitka ; Vyčichl, Jan
The paper deals with numerical analysis of hip joint surgery effect to changes of acetabulum stress field and implant migration in acetabulum area. Pelvic bone geometry was obtained from computer tomography by semi-automatic generation. There are two main input parameters for the stress analysis. CE angle detailing the shape of acetabulum. Direction of loading substitute the femoral replacement. The numerical analysis compare shapes and peak values of stress field in acetabulum area. Ultimate values of first principal stress, third principal stress and total displacements were used as reference magnitudes. This ultimate values predict probable migration process. Numerical analysis results correspond well with after surgery clinical reports.
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Interakce acetabulární komponenty a pánevní kosti s vadou v cementové vrstvě
Vyčichl, Jan ; Jiroušek, Ondřej ; Jírová, Jitka
The article deals with contact stress analysis of pelvic bone after implantation of cemented acetabular component with imperfections of cemented layer. 3D high resolution FE model of pelvic bone was created from the sequence of CT--slices. Imperfections were created both in the cement layer and in the bone tissue by drilling fixation holes. Boolean operations were used for inserting the spherical cemented component. Two contacts were defined in the FE model. The first contact is defined between the cement layer and the pelvic bone and the second one is between the cement layer and the polyethylene cup. The model was loaded by quasi--static joint forces, representing the maximum value of stance phase of gait (Bergmann HIP98). The FE model was used to ascertain the contact stress conditions in the underlying subchondral bone.
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Contact analysis of acetabular cup and pelvic bone
Vyčichl, Jan ; Jiroušek, Ondřej
A finite element study of factors influencing the contact stress in the pelvic bone after implantation of different designs of acetabular components is presented in the paper. The development of the geometry of the pelvic and the acetabular components is shortly described. The model is loaded according to a normal walk and the interaction of the components with subchondral bone is studied. The different designs of the cups are compared using the results of the contact analysis.
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