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Zjišťování materiálových vlastností houbovité kostní tkáně optickou metodou
Kytýř, Daniel ; Jiroušek, Ondřej ; Žák, Ondřej
Article deals with material properties of spongy bone assessed by optical identification based on surface texture registration.Strains at the specimen surface were measured using high-resolution CCD camera and optical identification method was used to trace their position during deformation. Centres of gravity of the markers are then considered to be vertices of connected triangles for which fields of displacement and strain are calculated. The assessed displacements of the structure of trabecular bone are used to obtain strain-stress diagram.
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Vliv cervikokapitalní endoprotézy na změny napjatosti v kostní tkáni
Kytýř, Daniel ; Micka, Michal
The most common problem that may happen soon after hip hemiarthroplasty surgery is migration of the head of the acetabulumreplacement. In the operation records of the Orthopaedic Clinic of the 3rd Faculty of Medicine of the Charles University in Prague, the implants that migrated in different ways in the course of several months were retrieved and evaluated. There are two dominant directions of the replacement head migration: median migration into pelvis minor or migration in acetabular labrum direction. The aim of this research work is to analyse the migration of the replacement head in pelvic bone under various types of loading and shapes of acetabulum.
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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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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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Vliv tvaru pánevní kosti na pole napění po implantaci cerkvikokapitální endoprotézy
Kytýř, Daniel ; Jírová, Jitka ; Micka, Michal ; Jíra, J.
Migration of the implant head after hemiarthoplasty is a problem which appertain to nearly all patients. Article deals with development and utilization of parametrical FE model of the hip joint for numerical analysis of implant head migration. There are two main input parameters for the stress analysis. CE angle representing the shape of acetabulum and direction of the femoral replacement loading. To assess the influence of selected parameters on the implant migration and to enable easy comparison to patients X-Ray scanning, the analysis was carried out as axially symmetric 2D and 3D contact problem. Ultimate values of first principal stress, third principal stress and sum of displacements were used as a reference magnitude.
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