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1
Content available The effect of glassy carbon and cancellous bone admixture on performance and thermal properties of acrylic bone cements
Choryłek P., Postawa P.
Archives of Materials Science and Engineering
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2020
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Vol. 104, nr 1
30--40
EN
Purpose: of the research is to physically modify the composition of bone cements with glassy carbon and cancellous bone to improve its performance, reduce polymerization temperature and reduce the ability of cements the effect of admixture on the phenomenon of relaxation. Design/methodology/approach: SpinePlex bone cement was modified with glassy carbon powder with 20-50 pm granulation with Maxgraft®. Maxgraft cancellous bone has been ground to 20-50 pm grains. Samples of unmodified cements (reference) and modified with glassy carbon and cancellous bone were prepared for the tests. The glassy carbon powder and ground cancellous bone were premixed with the cement copolymer powder, and then the premix prepared this way was spread in a liquid monomer. To delay the polymerization process, all components were cooled before mixing to 15°C. The addition of glassy carbon was 0.4 g and the addition of cancellous bone was 0.2 g per 20 g of cement powder, i.e. about 1.96% by mass. Polymerization temperature, relaxation and differential scanning calorimetry tests were performed on the samples made. Findings: Additives used allow: to reduce the polymerization temperature, as well as rheological properties. During the studies it was found that the additive which can meet the requirements is glassy carbon in form of powder and cancellous bone. Research limitations/implications: The results presented in the publication require further advanced research, which will be the subject of further modification attempts by the research team. Practical implications: The conducted tests showed a significant effect of glassy carbon as a modifier on the mechanical properties of cement after its solidification, but also on the course of the polymerization process. Temperature registration tests during crosslinking, tests of mechanical properties (behaviour of cement samples under load) and DSC differential scanning calorimetry analysis confirmed that the addition of glassy carbon had an effect on each of these aspects. Originality/value: The original in these studies is the possibility to improve fundamental properties of the selected bone cements by using different than commonly used additives.
2
Content available Comparison of selected properties of cements modified with glassy carbon and cancellous bone
Choryłek P.
Archives of Materials Science and Engineering
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2020
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Vol. 105, nr 1
31--41
EN
Purpose: The aim of this manuscript was to study and analyse the properties of bone cement (VertaPlex) before and after modification with glassy carbon (Alfa Aesar) and human bone (MaxGraft). Design/methodology/approach: To achieve the assumed goal, a series of samples was made - five samples for each mixture, where: 5 bone cement samples, 5 bone cement samples mixed with 20-50 μm glassy carbon in the ratio of 1 g carbon per 40 g of cement, and 5 samples of bone cement mixed with 20-50 μm glassy carbon and human bone in the ratio of 1 g of carbon per 40 g of cement and 0.4 g of bone per 40 g of cement. The produced samples (4 for each mixture, 1 was the reference sample) were subjected to tests - compression test, microscopic observations with a 3D microscope, surface profile tests and hardness tests. Findings: The study has shown that modifications with glassy carbon and bone change the mechanical properties, as well as the strength of the samples. Compression tests have shown that the material without admixtures is characterized by the highest compressive strength and the doping of the glassy carbon itself makes the material more brittle. A significant increase in hardness was also observed for samples with glassy carbon and bones after the pressing process. Practical implications: The study was made synthetically, without taking into account the effect of the environment of body fluids and the human body temperature. This study is an introduction to further considerations where samples for which these conditions will be applied are currently being prepared. Originality/value: For commercial use, in treatment of patients, cements modified with glassy carbon and bone glassy carbon have not been used so far. Due to the prerequisites of a positive effect of glassy carbon addition on osseointegration and biocompatibility, the study in this area has been undertaken.
3
Nieliniowo lepkosprężyste równanie konstytutywne gąbczastej tkanki kostnej i identyfikacja stałych materiałowych
Pawlikowski M., Jankowski K., Kokot G., Skalski K., Makuch A.
Inżynieria Powierzchni
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2018
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nr 1
12--17
PL
W pracy sformułowano nowe równanie konstytutywne dla gąbczastej tkanki kostnej człowieka. Zapostulowano funkcję energii odkształcenia, która opisuje sprężystą odpowiedź tkanki na obciążenie. W modelu konstytutywnym uwzględniono także nieliniową lepkosprężystość. Stałe materiałowe w równaniu konstytutywnym zidentyfikowano na podstawie wyników testów relaksacji naprężeń i monotonicznego ściskania metodą dopasowania krzywych. Wykorzystano tutaj algorytm Levenberga-Marquardta metody najmniejszych kwadratów. Na podstawie testów relaksacji zidentyfikowano wartości czasów relaksacji, natomiast na podstawie testów monotonicznego ściskania określono stałe sprężyste i lepkosprężyste. Testy były wykonane w temperaturze pokojowej na prostopadłościennych próbkach kości gąbczastej uzyskanych z główek kości udowej podczas operacji wszczepienia endoprotezy stawu biodrowego.
EN
In the paper a new constitutive equation for human cancellous bone tissue was formulated. A strain energy function was postulate, which describes the elastic response of the tissue to the load. The nonlinear viscoelasticity was also taken into account in the constitutive model. The material constants in the constitutive equation were identified on the basis of the results of stress relaxation tests and monotonic compression tests using the curve fitting method. The Levenberg-Marquardt algorithm of the least square method was used here. On the basis of the relaxation tests, the values of relaxation times were identified, while the elastic and viscoelastic constants were determined on the basis of monotonic compression tests. The tests were performed at room temperature. On the cuboidal samples of cancellous bone obtained from femoral heads during the surgeries of hip joint prosthesis implantation.
4
Content available Human cancellous bone mechanical properties and penetrator geometry in nanoindentation tests
Makuch A. M., Skalski K. R.
Acta of Bioengineering and Biomechanics
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2018
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Vol. 20, no. 3
153--164
EN
The goal of the study was to determine the influence of the penetrator geometry on the human cancellous bone mechanical properties in indentation tests. The aim of this research was also the assessment of the material properties of bone structures, having in mind the energy aspects of the curve obtained in the cycle: inelastic loading and elastic unloading. Methods: The samples were resected from a femoral heads of patients qualified for a hip replacement surgery. During the Depth Sensing Indentation tests, hardness and elastic modulus of the cancellous bone tissue were measured using the spherical and Vickers penetrators. Measurements were made in a node and in a trabecula for each sample. Results: The analysis of the measurement results and the calculations of total energy, i.e., elastic and inelastic, and those of the parameters of hardness and elasticity made it possible to assess the influence of the penetrator geometry on the mechanical properties of bone structures at a microscopic level. Conclusions: It was found, with respect to the methodology of indentation, that without determining the shape of the penetrator and the site of the indentation, an objective assessment of the micro mechanical properties of the tested material is not possible.
5
Zmiany mikrostruktury i charakterystyk naprężeniowo-odkształceniowych kości gąbczastej pozyskiwanej w zabiegach alloplastyki
Jankowski K., Pawlikowski M., Makuch A., Skalski K., Kokot G., Szlązak K.
Inżynieria Powierzchni
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2017
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nr 3
38--45
PL
W pracy przedstawiono wyniki badań zmian zachodzących w porowatej strukturze ludzkiej kości gąbczastej poddanej obciążeniom ściskającym. Do oceny zmian wykorzystano maszynę wytrzymałościową MTS Bionix oraz mikrotomograf SkyScan. Dzięki wykonywaniu projekcji mikrotomograficznych przed próbą ściskania kości i po niej zarejestrowano nie tylko charakterystyki naprężeniowo-odkształceniowe i zmianę sztywności kości, ale również ewolucję mikrostruktury (zmianę geometrii porów, przesunięcia, rotację, odkształcenia i pękanie beleczek kostnych), co w dalszych badaniach pozwoli dokładniej opisać mechanizmy odkształceń biologicznych materiałów porowatych.
EN
The paper presents the results of studies on the changes of the porous structure of human cancellous bone obtained in the arthroplasty surgery of the pathologically altered hip joints. The MTS Bionix testing machine and SkyScan Micro tomograph were used in the assessment. By performing a microtomographic projection before attempting to compress the bone and afterwards not only were the stress-strain characteristics and change in stiffness of the bone recorded, but also the evolution of the microstructure (change in pore geometry, displacement, rotation, deformation and fracture of bone beams). This in further research will allow to more accurately describe mechanisms of biological deformation of porous materials.
6
Content available remote Morphology-based prediction of elastic properties of trabecular bone samples
Cosmi F.
Acta of Bioengineering and Biomechanics
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2009
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Vol. 11, nr 1
3-9
EN
Morphological characteristics of the trabecular structure, identified by micro-tomography, can be quantified by volume fraction and second-order fabric tensors. These parameters have been proved to be related to bone structural properties but the formulations so far developed between volume fraction, fabric and elastic properties are bone specific and the coefficients found for one bone are not directly applicable to other bones. In this work, a general relationship was determined that links volume fraction and Mean Intercept Length (MIL) to the trabecular structure stiffness as computed by means of numerical models on which compression tests are simulated. Preliminary results obtained for three pig and two rat bone structures show that, for the pooled data set, the model could predict approximately 99% of the variation of the numerically computed elastic moduli.
7
Techniki ultradźwiękowe w badaniach in vitro materiałów kostnych. Przegląd zastosowań
Kubik J., Pakuła M.
Zeszyty Naukowe. Mechanika / Akademia Techniczno-Rolnicza w Bydgoszczy
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2004
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Z. 54(243)
7-21
PL
W pracy zaprezentowano główne metody ultradźwiękowe stosowane w laboratoryjnych badaniach materiałów kostnych: metodę fali ciągłej i impulsowej, metody mikroskopii ultradźwiękowej i rozpraszania wstecznego. Zdefiniowano ilościowe miary wykorzystywane do charakteryzowania materiałów kostnych w oparciu o pomiary ultradźwiękowe oraz przedyskutowano ważniejsze problemy metodologiczne wynikające ze specyfiki badanych materiałów. Zwrócono uwagę na takie elementy jak niewielkie wymiary dostępnych próbek, niejednorodność i anizotropia materiałów oraz wielofazowy charakter ośrodka. W pracy zebrano reprezentatywne dane liczbowe dla wybranych rodzajów materiałów pochodzenia ludzkiego i zwierzęcego, wyznaczone z pomocą omawianych metod.
8
Symulacja numeryczna procesu tworzenia się struktury beleczkowej kości gąbczastej
Ścigała K., Kiełbowicz A., Słowiński J.
Systems : journal of transdisciplinary systems science
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2004
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Vol. 9, No. sp. II
827-832
PL
Przedstawiono wyniki analizy procesu tworzenia się struktur beleczek kości gąbczastej pod wpływem obciążenia na drodze adaptacji funkcjonalnej. W pracy analizowano nie ty!ko zgodność uzyskanych struktur pod względem ich kształtu, roziożenia i wymiarów lecz również charakterystyk mechanicznych. Uzyskane wyniki wskazują iż zastosowana procedura umożliwiają uzyskanie struktur zbliżonych do rzeczywistej kości również pod względem ich właściwości mechanicznych.
EN
Presented paper is focused on the simulation of modelling process of trabcculae structure of canceilous bone. Existing algorithm of process was adapted to create structures of overloded, normal an unloaded structure. Analysis was focused on the verification of similarity of mechanical properties of created structure and real bone tissue.
9
Content available remote Macroscopic Behaviour of Locking Materials with Microstructure. Part II. Deterministic and Reiterated Homogenization
Telega J.J., Jemioło S.
Bulletin of the Polish Academy of Sciences. Technical Sciences
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2001
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vol. 49, nr 3
407-418
EN
The formulae for the homogenized (macroscopic) potential were given in the case of elastic-locking solids with various periodic microstructures. The microstructures cover deformable and rigid inclusions, voids and fissures. Multi-level microstructure was studied by using the reiterated homogenization.
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