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    Wyświetlanie 1-5 z 5
    Tytuł:
    Gradient composite materials for artificial intervertebral discs
    Autorzy:
    Migacz, K.
    Chłopek, J.
    Morawska-Chochół, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/306718.pdf
    Data publikacji:
    2014
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    kompozyty
    materiał gradientowy
    krążek międzykręgowy
    composite
    gradient material
    intervertebral disc replacement
    Opis:
    Composites with the gradient of the Young’s modulus constitute a new group of biomimetic materials which affect the proper distribution of stresses between the implant and the bone. The aim of this article was to examine the mechanical properties of gradient materials based on carbon fibre-polysulfone composite, and to compare them to the properties of a natural intervertebral disc. Gradient properties were provided by different orientation or volume fraction of carbon fibres in particular layers of composites. The results obtained during in vitro tests displayed a good durability of the gradient materials put under long-termstatic load. However, the configuration based on a change in the volume fraction of the fibres seems more advantageous than the one based on a change of the fibres’ orientation. Studied materials were designed to replace the intervertebral disc. The effect of the Young’s modulus of the material layers on the stress distribution between the tissue and the implant was analyzed and the biomimetic character of the gradient composites was stated. Unlike gradient materials, the pure polysulfone and the non-gradient composite resulted in the stress concentration in the region of nucleus pulposus, what is highly disadvantageous and does not occur in the stress distribution of natural intervertebral discs.
    Źródło:
    Acta of Bioengineering and Biomechanics; 2014, 16, 3; 3-12
    1509-409X
    2450-6303
    Pojawia się w:
    Acta of Bioengineering and Biomechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Assessment of postural stability in patients with lumbar spine chronic disc disease
    Autorzy:
    Truszczyńska, A.
    Dobrzyńska, M.
    Trzaskoma, Z.
    Drzał-Grabiec, J.
    Tarnowski, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/307493.pdf
    Data publikacji:
    2016
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    postawa ciała
    ból przewlekły
    stabilność
    dysk
    degenerative disc disease
    postural stability
    chronic pain
    Lumbar intervertebral disc
    Opis:
    Purpose: The pain, motor and sensory deficits are common symptoms of the lumbar disc disorder, and they can significantly affect human postural control. The aim of this study was to assess postural stability in patients with severe symptoms of lumbar spine disc disease qualifying them for surgical treatment and to compare them with a control group. Methods The study involved 103 subjects: 54 patients and 49 healthy subjects. Patient’s mean age was 46.4 ± 11.3 years, mean body height 172.2 ± 10.3 cm, mean body mass was 83.1 ± 18.9 kg and mean body mass index (BMI) was 27.9 ± 5.2 kg m-2. The mean time of their recent pain episode was 9.7 ± 8.5 month. Results: We found statistically significant differences between postural stability in patients with lumbar spine disc disease and the control group. The measurements taken with eyes closed, as compared with the clinical control group, revealed higher and statistically significant values of the mean amplitude of COP, mean amplitude of COP on sagittal plane, and maximal sway in sagittal plane parameters. The analysis of pressure value differences between the right and left lower limbs in both groups revealed statistical significance. In the study population the difference was significantly greater in comparison to the control group. The patients has significantly greater asymmetry of lower limb load. Conclusions: 1. Patients with lumbar spine discogenic pain had decreased postural control. 2. The patients had significant asymmetry in foot pressure, resultant from pain radiating to a lower limb.
    Źródło:
    Acta of Bioengineering and Biomechanics; 2016, 18, 4; 71-77
    1509-409X
    2450-6303
    Pojawia się w:
    Acta of Bioengineering and Biomechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Spinal sections and regional variations in the mechanical properties of the annulus fibrosus subjected to tensile loading
    Autorzy:
    Żak, M.
    Pezowicz, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/307024.pdf
    Data publikacji:
    2013
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    intervertebral disc
    annulus fibrosus
    tensile properties
    dissipated energy
    hydration
    krążek międzykręgowy
    naprężenie
    nawodnienie ustroju
    Opis:
    The annulus fibrosus is the primary load-bearing component of the intervertebral disc responsible for proper transfer of loads in the spine. The aim of this study was to determine selected mechanical parameters of multilayer specimens of the annulus fibrosus of the intervertebral disc during uniaxial tensile loading. The anatomical location (anterior/posterior) of the test specimens of the annulus fibrosus and its location along the length of the spine were analysed to determine their impact on the maximum failure force, stiffness, the value of Young’s modulus and dissipated energy. The results indicated high energy losses over the five consecutive precondition loops while the value of the force remained at a constant level. The thoracic and lumbar specimens showed the highest values of the parameters analysed. There were also significant changes depending on the anatomical region of the intervertebral disc, where anterior specimens demonstrated higher mechanical values compared to posterior specimens.
    Źródło:
    Acta of Bioengineering and Biomechanics; 2013, 15, 1; 51-59
    1509-409X
    2450-6303
    Pojawia się w:
    Acta of Bioengineering and Biomechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Quasi-static and dynamic properties of the intervertebral disc : experimental study and model parameter determination for the porcine lumbar motion segment
    Autorzy:
    Araujo, A. R. G.
    Peixinho, N.
    Pinho, A. C. M.
    Claro, J. C. P.
    Powiązania:
    https://bibliotekanauki.pl/articles/306566.pdf
    Data publikacji:
    2015
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    krążek międzykręgowy
    wytężenie dynamiczne
    sztywność
    ściskanie osiowe
    intervertebral disc
    dynamic response
    stiffness
    axial compression
    quasi-static response
    Opis:
    Purpose: The study of axial loading is essential to determine the properties of intervertebral disc. The objectives of this work are (1) to quantify the mechanical properties of porcine lumbar intervertebral discs under static and cyclic compressive loading, and (2) to determine the parameters of a five-parameter rheological model for porcine and compare them with those obtained for human lumbar intervertebral discs. Methods: Thus, the porcine lumbar motion segments were subjected to quasi-static and dynamic compression tests. The quasi-static tests were used to obtain the static stiffness coefficient at different strain rates, while the data from the cyclic compressive tests were used to both determine the dynamic stiffness coefficient and to be fitted in a 5-parameter model, in order to simulate the creep response of the porcine intervertebral discs. Results: The results demonstrated that dynamic stiffness coefficient of porcine discs is between four and ten times higher than the static stiffness coefficient, depending on load applied. The parameters of the rheological model suggested a low permeability of nucleus and endplate during the fast response of porcine discs. In addition, the fast response in terms of displacement is four times higher than those documented for human discs. Conclusions: This study revealed that care must be taken on the comparison between porcine and human discs, since they present different behaviour under quasi-static and dynamic compressive loading.
    Źródło:
    Acta of Bioengineering and Biomechanics; 2015, 17, 4; 59-66
    1509-409X
    2450-6303
    Pojawia się w:
    Acta of Bioengineering and Biomechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A finite element model of the L4-L5-S1 human spine segment including the heterogeneity and anisotropy of the discs
    Autorzy:
    Jaramillo, H.
    Gomez, L.
    Garcia, J. J.
    Powiązania:
    https://bibliotekanauki.pl/articles/951814.pdf
    Data publikacji:
    2015
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    kręgosłup
    metoda elementów skończonych
    segment L4-L5-S1
    krążek międzykręgowy
    model hipersprężysty
    intervertebral disc
    L4-L5-S1 segment
    finite element model
    human spine
    hyperelastic model
    Opis:
    With the aim to study disc degeneration and the risk of injury during occupational activities, a new finite element (FE) model of the L4-L5-S1 segment of the human spine was developed based on the anthropometry of a typical Colombian worker. Beginning with medical images, the programs CATIA and SOLIDWORKS were used to generate and assemble the vertebrae and create the soft structures of the segment. The software ABAQUS was used to run the analyses, which included a detailed model calibration using the experimental step-wise reduction data for the L4-L5 component, while the L5-S1 segment was calibrated in the intact condition. The range of motion curves, the intradiscal pressure and the lateral bulging under pure moments were considered for the calibration. As opposed to other FE models that include the L5-S1 disc, the model developed in this study considered the regional variations and anisotropy of the annulus as well as a realistic description of the nucleus geometry, which allowed an improved representation of experimental data during the validation process. Hence, the model can be used to analyze the stress and strain distributions in the L4-L5 and L5-S1 discs of workers performing activities such as lifting and carrying tasks.
    Źródło:
    Acta of Bioengineering and Biomechanics; 2015, 17, 2; 15-24
    1509-409X
    2450-6303
    Pojawia się w:
    Acta of Bioengineering and Biomechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-5 z 5

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