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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

Changes of structure and properties of PMMA-based bone cements with hydroxyapatite after degradation process

Laska-Leśniewicz Anna, Raczyńska Małgorzata, Wrotniak Maciej, Sobczyk-Guzenda Anna

Engineering of Biomaterials

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2019

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Vol. 22, no. 151

9--16

EN

PMMA-based bone cements are commonly used for implant fixation or as bone void fillers. Hydroxyapatite added as a filler to bone cement may positively affect the final properties of the material, in particular its biological properties. In this study, the preparation of poly(methyl methacrylate)-based bone cements with incorporated hydroxyapatite (HAp) is reported. The purpose of this article is to examine the proper-ties of bone cements enriched with HAp filler (the concentration of 3wt% and 6wt%) and reveal the changes in the composites properties (chemical structure, surface morphology and distribution of HAp in the composite matrix, moisture absorption, hardness in Shore D scale) during the long-term incubation in the PBS (phosphate-buffered saline) solution at 37°C. The incubation lasted up to 21 days, but only the period when the changes actually occurred was analysed. The studies have shown that the samples containing HAp absorb more moisture and have a lower hardness. These characteristics vary depending on the concentration of HAp. There is no elution of HAp and ZrO2 from the composite during the incubation. The surface morphology and chemical structure do not change during long-term studies. The obtained bone cements are characterized by high stability in the PBS solution.

6

Antibacterial activity assessment of bioactive modifiers for bone cements

Wekwejt M., Pałubicka A., Świeczko-Żurek B.

Engineering of Biomaterials

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2018

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Vol. 21, no. 148

58

7

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.

8

On the choice of thickness of the cement mantle in cemented hip arthroplasty

Levadnyi I., Awrejcewicz J., Loskutov A., Szymanowska O.

Journal of Theoretical and Applied Mechanics

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2017

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Vol. 55 nr 4

1235--1244

EN

Recommendations for the optimal thickness of the cement mantle in cemented hip arthroplasty are outlined based on the results obtained with the finite element method. The investigations show that distal femur cement thickness higher than 2 mm positively affects mechanical behaviour of the cement mantle and can be useful in reducing stress-strain levels in the distal part of the femur what leads to prevention of development of a stress-shielding effect. The results of the study can contribute to the success of long-term implants.

9

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.

10

Potential degradation of bone cement used in maxillo-facial surgery

Wekwejt M., Świeczko-Żurek B., Bartmański M.

Engineering of Biomaterials

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2017

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Vol. 20, no. 143 spec. iss.

31

11

Acrylic bone cements modified with PEG/alginic acid shape stabilized phase change materials

Sobota D., Król-Morkisz K., Pielichowska K.

Engineering of Biomaterials

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2017

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Vol. 20, no. 143 spec. iss.

57

12

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.

13

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.

14

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.

15

Wpływ obróbki cieplnej hydroksyapatytu dotowanego tytanem (TiHA) na właściwości i zachowanie w warunkach in vitro kompozytów na bazie siarczanu(VI) wapnia i TiHA

Czechowska J., Paszkiewicz Z., Zima A., Pijocha D., Ślósarczyk A.

Materiały Ceramiczne

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2011

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T. 63, nr 4

758-764

PL

W ostatnich latach coraz większe zainteresowane budzą biomateriały do wypełniania ubytków kostnych wykazujące właściwości wiążące in situ. Obecnie na rynku dostępnych jest wiele komercyjnych produktów, jednak wciąż nie ustają próby zmierzające do wytworzenia nowego substytutu kostnego, o ulepszonych właściwościach mechanicznych i biologicznych. Materiały oparte na fosforanach(V) wapnia (włącznie z hydroksyapatytem, HA) cieszą się szczególnym zainteresowaniem ze względu na ich doskonalą biozgodność oraz bioaktywność. Siarczan(VI) wapnia od szeregu lat używany jest do celów klinicznych, a jako wypełniacz kostny jest dobrze tolerowalny przez organizm. W obecnych badaniach opracowano dwufazowy, wiążący substytut kostny na bazie siarczanu(VI) wapnia oraz dotowanego tytanem hydroksyapatytu. Do wytworzenia tego biomateriału użyto półwodnego siarczanu(VI) wapnia (CSH) oraz trzech proszków hydroksyapatytowych dotowanych tytanem (TiHA): surowego oraz kalcynowanych w 800 i 1250°C. Celem badań było określenie wpływu obróbki cieplnej hydroksyapatytu dotowanego tytanem na czas wiązania, właściwości mechaniczne oraz zachowanie w warunkach in vitro w sztucznym osoczu krwi (SBF) kompozytu opartego na siarczanie(VI) wapnia i TiHA. Rezultaty badań wskazują, że materiały wiążące TiHA-CS są biokompatybilne, łatwo kształtowalne oraz posiadają potencjalne zastosowanie do uzupełniania ubytków kostnych.

EN

Biomaterials with the self-setting in situ properties for the use in human bone tissue augmentation have attracted increasing attention in recent years. Currently many commercial products exist on the market, however the efforts still proceed to achieve a novel bone substitute with improved mechanical and biological properties. Calcium phosphate based materials, including hydroxyapatite (HA), have been of special interest due to their excellent biocompatibility and bioactivity. Calcium sulfate has also a long history of clinical use and it is known to be well-tolerated by organism when used as a bone filler. In this study, a biphasic, self-setting bone substitute was developed, basing on calcium sulfate and titanium doped hydroxyapatite. Calcium sulfate hemihydrate (CSH) and three different Ti doped hydroxyapatite powders (TiHA): raw and calcined at 800°C and 1250°C were used to form the new biomaterial. The aim of this study was to investigate how heat treatment of titanium doped hydroxyapatite influenced the setting time, mechanical properties and in vitro behaviour in simulated body fluid (SBF) of the calcium sulfate - TiHA composites. The results of our studies suggest that TiHA-CS self-setting materials are biocompatible, easily shapeable and have a potential to be applied for bone substitution.

16

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.

17

Assessment of fracture toughness and microstructure of bone cements

Szarek A., Kwiatkowski D., Dębski H.

Kompozyty

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2011

|

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.

18

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

Szarek A., Gnatowski A.

Aktualne Problemy Biomechaniki

|

2011

|

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.

19

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

Nowacki J., Sajek A.

Inżynieria Materiałowa

|

2010

|

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.

20

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.