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1

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

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

Numerical prediction of component-ratio-dependent compressive strength of bone cement

Machrowska Anna, Karpiński Robert, Jonak Józef, Szabelski Jakub, Krakowski Przemysław

Applied Computer Science

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2020

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Vol. 16, no 3

87--101

EN

Changes in the compression strength of the PMMA bone cement with a variable powder/liquid component mix ratio were investigated. The strength test data served to develop basic mathematical models and an artificial neural network was employed for strength predictions. The empirical and numerical results were compared to determine modelling errors and assess the effectiveness of the proposed methods and models. The advantages and disadvantages of mathematical modelling are discussed.

4

Vertebroplasty and kyphoplasty - advantages and disadvantages used bone cement of PMMA

Choryłek P.

Journal of Achievements in Materials and Manufacturing Engineering

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2019

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Vol. 92, nr 1-2

36--49

EN

Purpose: This paper is a review of literature where the analyses of the commonly used bone cements were carried out especially: methods of manufacturing, surgical techniques, mechanical properties, biocompatibility studies as well as possibility of improvement some properties by using additives. Design/methodology/approach: The aim of this publication is the analysis of the state of knowledge and treatment methods on compression fractures, approximation of the specifics of compression fractures, presentation of minimally invasive percutaneous surgical techniques, description of features of the most common used bone cement on matrix Poly(methyl methacrylate) – (PMMA) and presentation cement parameters which affect potential postoperative complications. Findings: In considering to review of actual state of knowledge there is a need to find the additives which allow: to reduce the polymerization temperature, improve the biocompatibility as well as mechanical properties. During the studies it was found that the additive which can meet the requirements is glassy carbon in form of powder. Practical implications: Discussion allows to prepare samples during practical work with new kind additives in composite with bone cement as matrix. Originality/value: The original in this discussion is the possibility to improve fundamental properties of the selected bone cements by using different than commonly used additives.

5

The tension-shear fracture behavior of polymeric bone cement modified with hydroxyapatite nano-particles

Ayatollahi M. R., Mirmohammadi S. A., Shirazi H. A.

Archives of Civil and Mechanical Engineering

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2018

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Vol. 18, no. 1

50--59

EN

Polymethylmethacrylate (PMMA)-based bone cement is a well-known polymer in the medicine, especially orthopedic. However it has some drawbacks like lack of enough biocompatibility and poor mechanical properties. These problems can be addressed by incorporation of nano-materials. Hydroxyapatite has been proved to enhance biocompatibility of acrylic bone cements. This bioceramic can affect the mechanical properties of polymeric cements as well. In this study, a number of fracture tests were carried out to investigate the influence of nano-hydroxyapatite (HA) on the fracture behavior of acrylic bone cement under combined tension-shear (mixed mode) loading conditions. Semi-circular specimens were prepared by incorporating different amounts of HA powder into the cement matrix. It was found that adding up to 10 wt% HA into the cement causes an increase in the fracture toughness of PMMA/HA nano-composite in all modes. However, pure cement exhibited the greatest fracture resistance among all samples. Moreover, the comparison between the experimental and theoretical results showed that the generalized maximum tangential stress criterion could estimate the experimental data satisfactorily.

6

Badania bioaktywności modyfikowanego cementu kostnego : przegląd literaturowy

Wekwejt M., Świeczko-Żurek B.

Inżynier i Fizyk Medyczny

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2017

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Vol. 6, nr 4

261--268

PL

Celem pracy jest przybliżenie aspektów związanych z modyfikowaniem cementu kostnego w celu nadania mu właściwości bioaktywnych. Przedstawiono obecnie stosowane bioaktywne modyfikacje, które mają charakter profilaktyczny (zapobiegają infekcjom), terapeutyczny (zwalczają bakterie) oraz pobudzający osteointegrację. Ukazano metody oceny modyfikacji bioaktywnych i zreferowano ich procedury, m.in. badania mikroskopowe, starzenie w roztworze Ringera, określanie dawki uwalnianej modyfikacji, pomiar strefy zahamowania wzrostu bakteryjnego, badania cytotoksyczności, przylegania i proliferacji komórek żywych, badanie pirogenności, test hemolityczny oraz badania kliniczne.

EN

The aim of the literature review is to present the aspects related to modification of bone cement to give it bioactive properties. It presents currently used bioactive modifications, which have preventive activity (reduce the risk of infection), therapeutic activity (fight against bacteria) and stimulating osteointegration. Shows methods for evaluating bioactive modifications and discusses procedures, i.a.: microscopic studies, aging in Ringer’s solution, determination of release dose, measurement of bacterial growth inhibition zone, cytotoxicity test, adhesion and proliferation of live cells survey, pyrogenicity test, haemolytic assay, and clinical studies.

7

Antimicrobal and ostheointegration activity of bone cement contains nanometals

Świeczko-Żurek B.

Journal of Achievements in Materials and Manufacturing Engineering

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2016

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Vol. 74, nr 1

15--21

EN

Purpose: One of the major problems in bone surgery are infections – especially those occurring in the course of the operating on the patients with lowered immunity system, because they carry the danger of complications. In the Mechanical Department of Technical University of Gdansk, there has been carried the research with the use of bone cement and metal nanoparticles. Design/methodology/approach: The bone cement was used without supplement or with one or two drugs. These experiments are the latest, because include pure bone cement (without drugs) with nanometals. The titanium specimens was covering with such compose coating. The implant was inserted into rat`s thigh for six weeks. Afterwards the implant was removed from the body and examined by means of scanning electron microscope. Simultanously biological research was carried out. Bonless samples were placed into bacterial liquid, generated by the researcher (the Patent number P 409082 ) containing five most frequently occurring bacteria in human body. Findings: Result of the SEM research was positive – there was good adhesion of ostheoblasts to the surface and there were no traces of infection. Practical implications: The research concerns bone cement with nanoparticles proves, that nanoparticles are the alternatives to antibiotics.

8

Effects of Interaction between Two Cavities on the Bone Cement Damage of the Total Hip Prothesis

Sahli A., Benbarek S., Bouiadjra B., Mokhtar B. M.

Mechanics and Mechanical Engineering

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2014

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Vol. 18, nr 2

107--120

EN

In orthopedic surgery and more particularly in total hip arthroplasty, the fixation of implants is usually done with surgical cement consisting essentially of polymer (PMMA). Fractures and loosening appear after a high stress gradient. The origin of this phenomenon is the presence of micro–cavity located in the volume of PMMA. The aim of this study is to investigate the effect of the interaction between two cavities on the cement damage where the external conditions (loads and geometric forms) can cause the fracture of the cement and therefore aseptic loosening of the prosthesis. A numerical model is generated using finite element method to analyze the damage of orthopedic cement around the microcavity and estimate the length of the crack emanating from microcavity for each position of the human body. Result show that the damaged area is influenced by the cavity shape (only elliptical cavity shape can initiate damage). The most dangerous cavity position is located in the middle of the cement socket, on the axis of the loading. The distance between two cavities has an effect if it is less than 100 μm. One can estimate the initiation of a crack of maximum length of 16μm.

9

Chemically bonded, calcium phosphate based bioceramics with addition of calcium sulphate

Czechowska J., Siek D., Zima A., Ślósarczyk A.

Archives of Materials Science and Engineering

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2014

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Vol. 66, nr 1

5--12

EN

Purpose: Calcium phosphate cements (CPCs) are extensively used as synthetic bone grafts due to their excellent bioactivity, moldability and ability to set in vivo. Although there are some commercial CPCs in the market, there are many ongoing research directed mainly to improve some of their properties, such as mechanical strength, cohesion or resorbability. The purpose of the study was to develop a more systematic approach for the formulations of CPCs and to obtain complex composite that will be gradually resorbed in vivo. Design/methodology/approach: In the present studies cements composed of different ratios of α-TCP, Mg2+/CO32- co-substituted hydroxyapatite (MgCHA) and calcium sulphate were developed. The obtained materials were characterized in terms of setting time, compressive strength and open porosity. XRD technique was employed to determine the phase composition of the initial powders and the final materials. Chemical stability of the studied materials was checked. Bioactive potential of the bone cements was evaluated in accordance to Kokubo’s protocol. Findings: The investigated materials possess excellent handling properties, appropriate setting times (initial: 6-8 min, final-17-21 min) and compressive strength comparable to cancellous bone (6-12 MPa). The expected gradual resorption of composites (resorbability: CSD >> α-TCP > MgCHA) is believed to facilitate a healing process and stimulate bone regeneration. Research limitations/implications: Further in vitro and in vivo experiments need to be done to confirm cytocompatibility of these biomaterials. Originality/value: The new chemically bonded bioceramics with addition of calcium sulphate was developed. A systematic approach for the formulations of CPCs on the basis of α-TCP, MgCHA and calcium sulphate was performed. The obtained chemically bonded bioceramics may have a chance to be apply as bone substitutes in low load bearing places.

10

Mikrostruktura, skład fazowy i wytrzymałość mechaniczna nowych substytutów kostnych opartych na hydroksyapatycie, fosforanie magnezu i siarczanie(VI) wapnia

Pijocha D., Czechowska J., Bućko M. M., Paszkiewicz Z., Ślósarczyk A.

Materiały Ceramiczne

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2011

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T. 63, nr 4

773-778

PL

Z powodu znakomitej biokompatybilności i bioaktywności fosforany wapnia takie jak hydroksyapatyt (Ca10(PO4)6(OH)2) oraz ß-TCP (Ca3(PO4)2) są z powodzeniem stosowane jako substytuty kostne w ortopedii, chirurgii twarzoczaszki i stomatologii. Jednak, zastosowanie tych materiałów w medycynie ogranicza się do miejsc nie przenoszących znacznych obciążeń ze względu na ich kruchość i niską wytrzymałość mechaniczną. Ich niedostatkiem jest także niezadowalająca poręczność chirurgiczna utrudniająca założenie do ubytków kostnych. Praca dotyczy opracowania i oceny kompozytu złożonego z hydroksyapatytu (HA), cementu magnezowo–fosforanowego (MPC) oraz półwodnego siarczanu(VI) wapnia (CSH) o parametrach optymalnych dla zastosowań medycznych.

EN

Because of excellent biocompatibility and bioactivity, calcium phosphates such as hydroxyapatite (Ca10(PO4)6(OH)2) and ß-TCP (Ca3(PO4)2) are successfully used as bone substitutes in orthopaedics, maxillofacial surgery and dentistry. However, due to low mechanical strength and brittleness, the application of these biomaterials in medicine is limited to places not loaded significantly. Limited surgical handiness is also a disadvantage of calcium phosphates, what makes diffi cult to place the material into bone voids. This study is focused on development of composites containing hydroxyapatite (HA), magnesium–phosphate cement (MPC) and calcium sulphate hemihydrate (CSH), and showing the optimum parameters for medical applications.

11

Assessment of fracture toughness and microstructure of bone cements

Szarek A., Kwiatkowski D., Dębski H.

Kompozyty

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2011

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R. 11, nr 3

192-196

EN

Bone cement used in orthopaedics (PMMA) is a viscoelastic material. Macroscopically, the cement structure is composed of aggregates in the form of polymer spheres with the dimensions of 10÷18 micrometers connected with polymerized monomer bridges. After mixing, it is initially a fluid, which then becomes increasingly viscous and hardens. During polymerization, the material is plastic and can be easily moulded and it penetrates deep into the fine trabecular structure of the bone. PMMA is characterized by low impact strength, which, in cements without fillers, reaches the level of KC = 1.16÷5.2 kJ/m2. This causes the material to show tendencies to crack at even a low dynamic load. A number of studies have demonstrated that PMMA tends to fragment and chip in artificial hip joints. The paper presents the investigations of the PMMA structure carried out for bone composites with implanted hip joint prostheses. The results of empirical investigations which allow for the determination of PMMA crack resistance were also presented. In order to determine crack resistance in bone cement, strength tests were carried out by means of an Inspekt Desk 20 machine manufactured by Hegewald & Peschke, equipped with a device for three-point bending. The measure of crack resistance was a critical value of the stress intensity factor KQ. In order to compare the results, numerical calculations of the stress intensity factor (WIN) were also carried out for the three-point bending of a SENB sample made of SIMPLEX P + carbon fibre.

PL

Stosowany w ortopedii cement kostny (PMMA) jest materiałem lepkosprężystym. Makroskopowo masa cementowa złożona jest z agregatów kulek polimeru o wymiarach 10÷18 mikrometrów łączonych mostkami spolimeryzowanego monomeru. PMMA może być stosowany jako materiał bez domieszek lub z wprowadzonymi wypełniaczami. Po zmieszaniu początkowo jest płynną substancją, która następnie staje się coraz bardziej lepka i twardnieje. Podczas polimeryzacji jest on plastyczny, daje się dowolnie kształtować i penetruje nawet w głąb drobnej struktury beleczkowej kości. PMMA charakteryzuje się niską udarnością, która dla cementów bez wypełniaczy ma wartości w zakresie KC = 1,16÷5,2 kJ/m2. W związku z tym wykazuje on skłonność do przypadkowego pękania pod wpływem niewielkich obciążeń dynamicznych. Liczne badania dowodzą, iż PMMA ma skłonność do fragmentacji i wykruszania się cementu podczas użytkowania sztucznego stawu biodrowego. W artykule przedstawiono badania struktury PMMA przeprowadzone na kompozytach kostnych z zaimplantowaną endoprotezą stawu biodrowego. Przedstawiono również wyniki badań eksperymentalnych pozwalających na określenie odporności PMMA na pękanie. W celu określenia odporności cementu kostnego na pękanie przeprowadzono badania za pomocą maszyny wytrzymałościowej Inspekt Desk 20 firmy Hegewald & Peschke wyposażonej w uchwyt do trójpunktowego zginania. Jako miarę odporności na pękanie przyjęto krytyczną wartość współczynnika intensywności naprężeń KQ. W celach porównawczych przeprowadzono również obliczenia numeryczne współczynnika intensywności naprężeń WIN podczas trójpunktowego zginania próbki SENB wykonanej z cementu SIMPLEX P + włókno węglowe.

12

The analysis of changes of thermal properties and structures of the bone cements after ageing processes

Szarek A., Gnatowski A.

Aktualne Problemy Biomechaniki

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2011

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z. 5

153--158

EN

This paper presents the results of the investigations of thermal properties and the structure of bone cements developed based on polymethyl methacrylate with addition of fillers and auxiliaries. DSC method was employed to determine glass transition temperature for the studied bone cements before and after the process of aging in water NaCl solution subject to electrolysis. The investigations were carried out for bone cements with different composition and different percentage share of the components. Two types of bone cements were used for the investigations: CMW1 manufactured by CMW and Palamed 40. Thermal properties were analysed using differential scanning calorimetry by means of Netzsch DSC 200 Phox equipment. The structure was examined by means of Nikon Eclipse E 200 optical microscope.

PL

W artykule określono metodą DSC wartości temperatury zeszklenia PMMA przed i po procesie starzenia w roztworze wodnym NaCl poddanym elektrolizie. Badania przeprowadzono dla PMMA o różnym składzie i udziale procentowym składników. Do badań zastosowano dwa rodzaje cementów kostnych: CMW1 oraz Palamed 40. Dla części materiału badawczego przeprowadzono proces przyspieszonego starzenia w celu określenia odporności chemicznej na czynniki powodujące korozję i degradację cementu kostnego. Badania właściwości termicznych wykonano metodą różnicowej kalorymetrii skaningowej, wykorzystując urządzenie DSC 200 Phox firmy Netzsch. Strukturę obserwowano pod mikroskopem optycznym firmy Nikon Eclipse E 200.

13

Modified bone cement microstructure numeric simulation

Nowacki J., Sajek A.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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Vol. 43, nr 2

533--541

EN

Purpose: The paper aimed at determining the strength of modified bone cement microstructure. Modification with aqueous hormone solution stimulates the growth of bone at a hip-joint endoprosthesis implantation site. Design/methodology/approach: In the first place, microstructure of modified cements was examined. This examination was a basis for statistical description of porosity obtained as a result of modification. Statistical data were used to create microstructure models in a programme being in agreement with FEM technique. Simulations were carried out on structures of 2 types of pores, i.e. those containing water and empty ones. Findings: Modification with aqueous solutions of modifying agents affects the structure and properties of bone cements. This is caused by formation of pores filled with aqueous solutions of modifying agents. This type of porosity decreases mechanical properties less than air-filled pores. Research limitations/implications: Numerical simulation of the stress and displacement pattern in juncture microstructure should be expanded with a simulation of bone-cement-implant system operation, which will allow estimation of an optimum value of modifying agent admixture, i.e. a value enabling the improvement of juncture biocompatibility not lowering at the same time its mechanical properties below a level set up in standard specifications. Practical implications: Microstructure simulations performed confirmed a manner of modified cement cracking observed on fractures. They showed formation of pore agglomerations where concentrating stresses may bring about the appearance of dangerous micro-fractures. Originality/value: Cement modification with aqueous solution and examination of the effect of admixture on microstructure mechanical properties.

14

Numerical simulation of microstructure and internal stresses of the modified bone cement

Nowacki J., Sajek A.

Inżynieria Materiałowa

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2010

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Vol. 31, nr 3

728-731

EN

Microstructure of bone cement modified by an aqueous solution of an enzyme - salmon calcitionin was considered. A statistical description of the porosity of obtained cements as a result of the modification has been done. Statistical data were used to create the microstructure models in a programme being in agreement with FEM technique. Simulations were carried out on the structures of two types of pores, i.e. those containing water and empty ones. Modification with aqueous solutions of agents affects the structure and properties of the bone cements were observed. This is caused by the formation of pores filled with the aqueous solution. Microstructure simulations confirmed a manner of modified cement cracking was observed on the fractures. The formation of pore agglomerations where concentrating stresses may bring about the appearance of dangerous microfractures was proved.

PL

Analizowano mikrostrukturę cementu kostnego nowej generacji modyfikowanego wodnym roztworem enzymu - kalcytoniny łososiowej, stosowanego w aloplastyce stawu biodrowego. Wykonano statystyczny opis porowatości cementu po modyfikacji, stanowiący podstawę opracowania metodą elementów skończonych modelu mikrostruktury cementu. Wykazano, że domieszkowanie wodnymi roztworami modyfikatorów ma wpływ na mikrostrukturę i właściwości cementów kostnych. Spowodowane jest to tworzeniem porów wypełnionych wodnymi roztworami modyfikatorów i powietrzem. Pierwszy rodzaj porowatości w mniejszym stopniu niż pory wypełnione powietrzem zmniejsza właściwości mechaniczne cementów. Wykazano powstawanie aglomeracji porów, w których koncentrujące się naprężenia mogą powodować pojawianie się mikropęknięć.

15

Ocena skłonności do starzenia polimerowego cementu kostnego

Kolczyk E., Balin A., Kusz D., Sobczyk K.

Engineering of Biomaterials

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2010

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Vol. 13, no. 96-98

4--9

PL

W pracy badano wpływ starzenia na właściwości polimerowego cementu kostnego. Proces starzenia cementu kostnego realizowano poprzez zastosowanie naświetlania promieniami rentgenowskimi oraz moczenia w roztworze Ringera. Przeprowadzono badania statycznego ściskania i zginania zgodnie z wymogami normy ISO 5833 oraz badania zmęczeniowe niskocyklowe. Na podstawie badań zmęczeniowych opracowano krzywe cyklicznego pełzania i charakterystykę dynamicznego modułu sprężystości. Po starzeniu cementu kostnego stwierdzono spadek wytrzymałości na zginanie odpowiednio po naświetlaniu promieniami rtg i moczeniu w roztworze Ringera o 23% i o 32% a modułu sprężystości na zginanie o 20% i o 21%. Wytrzymałość na ściskanie cementu kostnego po promieniowaniu rtg spadła o 4% a po moczeniu w roztworze Ringera wzrosła o 9%. Moduł sprężystości wzrósł o 7% po starzeniu w środowisku wodnym a po promieniowaniu rtg pozostał bez zmian. Zaobserwowano również wpływ starzenia na właściwości lepkosprężyste cementu kostnego po promieniowaniu rtg. Stwierdzono wzrost dynamicznego modułu sprężystości cementu kostnego oraz uzyskanie mniejszych odkształceń podczas pełzania.

EN

The paper describes the research into the influence of ageing on the properties of the polymer surgical cement. The process of ageing of the surgical cement was performed using X-ray radiation and soaking in Ringer’s solution. The studies of static compression and bending in compliance with ISO 5833 requirements and low-cycle fatigue tests were carried out. Based on the fatigue tests performed, the curves of cyclic creep were obtained and characteristics of dynamic elasticity modulus developed. After ageing of the surgical cement, a decrease of bending strength was identified after X-ray radiation and soaking in Ringer’s solution, by 23% and 32% respectively, while the modulus of bending elasticity by 20% and 21%. Compression strength of surgical cement after X-ray radiation decreased by 4%, and increased by 9% after soaking in Ringer’s solution. The modulus of compression elasticity increased by 7% after ageing in a wet environment, while after X-ray radiation it remained almost unchanged. Also, the influence of ageing on viscoelastic properties of surgical cement after X-ray radiation was observed. A decrease in the dynamic elasticity modulus of surgical cement was identified, while the deformations obtained during creep were smaller.

16

Wpływ procesów starzenia na wytrzymałość mechaniczną cementu kostnego

Szarek A.

Aktualne Problemy Biomechaniki

|

2010

|

z. 4

191--194

PL

Wytrzymałość mechaniczna poszczególnych elementów sztucznych stawów ma zasadnicze znaczenie na ich żywotność w organizmie. Ze względu na złożony stan naprężeń oraz agresywne środowisko wewnątrz organizmu człowieka powoduje, że wraz z upływem czasu zmieniają się właściwości wytrzymałościowe poszczególnych elementów endoprotez. Ponieważ wpływ starzenia na spadek wytrzymałości PMMA stosowanego do mocowania protezy w kości, może spowodować obluzowanie się protezy w kości, w artykule przedstawiono wyniki badań pozwalających na określenie wielkości tych zmian w okresie pierwszych 6 lat po polimeryzacji.

EN

Mechanical strength in each part of artificial joints is of essential importance to their life in the body. A complex distribution of stress combined with aggressive environment inside human body causes that strength properties in the part of endoprostheses change in the course of time. Since the effect of aging on the decline of strength in PMMA used for fixation of the prosthesis in bone might cause that the prosthesis comes loose in the bone, this paper presents the results of the investigations which allow for determination of the extent of these changes in the period of first 6 years after polymerization.

17

Time and mixing technique-dependent changes in bone cement SmartSet HV

Lelovics H., Liptakova T.

Acta of Bioengineering and Biomechanics

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2010

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Vol. 12, no. 4

63-67

EN

For the past fifty years bone cements based on polymethylmethacrylate (PMMA) have been used in orthopaedic surgery for fixation of endoprostheses, especially in the cases of total hip replacement. It was shown that during this period vacuum mixing minimalizes the number of unwanted pores and thereby influences the mechanical properties of the cement. It was also discovered that later polymerization of the cement after its implantation lasts up to 6 months and changes its mechanical properties. In this study, mechanical properties (microhardness and elastic modulus measured by microindentation) of hand- and vacuum-mixed acrylic bone cement SmartSet HVŽ were investigated and compared after different time of cement exposition. This study points out that the measures of changes occurring with time in mechanical properties of differently mixed cement samples are equal but microhardness and elastic modulus are different and depend upon the technology of mixing.

18

Wybrane aspekty spajania biomateriałów

Nowacki J., Sajek A.

Przegląd Spawalnictwa

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2009

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R. 81, nr 11

8-14

PL

Przedstawiono wybrane aspekty spajania biomateriałów. W obszarze eksperymentu określono mikrostrukturę i wytrzymałość domieszkowanego cementu kostnego, traktowanego jako spoiwo w implantacji endoprotezy w tkance kostnej. Domieszkowanie wodnym roztworem hormonu stymuluje wzrost kości w miejscu implantacji endoprotezy stawu biodrowego. Wykonano badania mikrostruktury domieszkowanych cementów. Badania te są podstawą do opisu statystycznego uzyskanej w wyniku domieszkowania porowatości. Dane statystyczne zostały wykorzystane do utworzenia modeli mikrostruktury w programie w konwencji MES. Symulacje prowadzono na strukturach dwóch typów porów: zawierających wodę i pustych. Wykazano, że domieszkowanie wodnymi roztworami modyfikatorów ma wpływ na strukturę i właściwości cementów kostnych. Spowodowane jest to tworzeniem porów wypełnionych wodnymi roztworami modyfikatorów. Ten rodzaj porowatości w mniejszym stopniu niż pory wypełnione powietrzem zmniejsza właściwości mechaniczne. Przeprowadzone symulacje mikrostruktury potwierdziły sposób pękania domieszkowanego cementu zaobserwowanego na przełomach. Ukazały powstawanie aglomeracji porów, w których koncentrujące się naprężenia mogą powodować pojawianie się groźnych mikropęknięć.

EN

Selected aspects of biomaterials bonding have been presented. In the range of the experiment, microstructure and strengths of doped bone cement treated as a binding material in implantation of an endoprothesis in osseous tissue have been determined. Doping with the water solution of a hormone stimulates growth of a bone in the place of implantation of a hip joint endoprothesis. Tests of microstructure of cements doped have been executed. Those tests make a base for statistical description of porosity obtained as a result of doping. Statistical data have been used to create microstructure models in the program in the MES convention. Simulations have been performed on structures of two types of pores: pores containing water and empty pores. It has been pointed out that doping with water solutions of modifying agents affected the structure and properties of bone cements. It is caused by formation of pores filled with water solutions of modifying agents. That type of porosity decreases mechanical properties in lower degree than pores filled with air. Microstructure stimulations, which have been performed, confirmed a way of cracking of doped cements observed in fractures. They showed arising of pores agglomerations, were concentrating stresses may cause occurring of dangerous microcracks.

19

Mechanical properties of biodegradable bone cement composites

Iskander B. A., Kamel N. A.

Górnictwo i Geoinżynieria

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2009

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R. 33, z. 4

119-133

EN

A material that can be used as a scaffold in tissue engineering must satisfy a number of requirements. These include biocompatibility, biodegradation to non toxic products within the time frame required for the application, process ability to complicated shapes with appropriate porosity, ability to support cell growth and proliferation, and appropriate mechanical properties, as well as maintaining mechanical strength during most part of the tissue regeneration. In the present work, the bone cement composites were prepared by mixing different ratios of calcium sulfate dehydrate (CaSO4.2H2O) filler (60, 65 and 70 wt%) with the polyester resin/NV, MMA, NV/MMA monomers mixture. The biodegradability of PSF crosslinked with NV, MMA and NV/MMA loaded with 60% gypsum was studied using Simulated Body Fluid SBF (pH 7.3) in vitro medium. The degradation rate of fumarate based polyesters as well as bone cement composites were measured as the percentage of weight loss over time of exposure to the SBF solutions. The mechanical properties showed different behavior according to the bone cement concentration. The compressive strength and the microstructure were also studied before and after immersing in SBF solution.

PL

Materiał, który może zostać zastosowany jako kościec w inżynierii anatomicznej musi spełniać szereg wymogów. Są to biokompatybilność, biodegradacja do produktów nietoksycznych w czasie wymaganym do implementacji, zdolność adaptacji do skomplikowanych form o odpowiedniej porowatości, zdolność do wspomagania wzrostu komórek i proliferacji oraz odpowiednie właściwości mechaniczne, jak również utrzymywanie siły mechanicznej podczas większości procesu regeneracji tkanki. W pracy przygotowano cementowe kompozyty kości poprzez zmieszanie w różnych proporcjach (60, 65 oraz 70%) wypełniacza, którym był dwuwodzian siarczanu wapnia CaSO4.2H2O z mieszaniną monomerów żywicy poliestrowej NV, MMA oraz NV wraz z MMA. Biodegradowalność PSF w połączeniu z NV, MMA oraz NV/MMA wypełniona w 60% gipsem była badana za pomocą Simulated Body Fluid (pH 7,3) w ośrodku vitro. Stopień degradacji poliestrów oraz cementowych kompozytów kostnych był mierzony jako utrata wagi w czasie działania roztworów SBF. Właściwości mechaniczne okazały się różne w zależności od koncentracji cementu kostnego. Siła kompresji i mikrostruktura były również badane przed i po imersji w roztworze SBF.

20

Variations of temperature of acrylic bone cements prepared by hand and vacuum mixing during their polymerization

Liptáková T., Lelovics H., Nečas L.

Acta of Bioengineering and Biomechanics

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2009

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Vol. 11, nr 3

47-51

EN

The aim of this work was to investigate variations of temperature in acrylic bone cement SmartSet HV during its polymerization as the function of mixing technique (hand mixing and vacuum mixing) and sample thickness. The temperature of 25-mm diameter samples differing in their thickness was monitored using a parallel plate measuring system of the compact rheometer preheated to the body temperature. The curves representing the temperature measured and average values of times needed to obtain the peak temperatures of the test samples prepared by different techniques of mixing are presented and discussed. It was found that the maximum temperature and also the times of peak temperatures rose with sample thickness but at different rate for each technique of mixing.