Properties Of Bone Cement Research Articles

Developing of PMMA Bone Cement Performance by Modified TiO2NPs

Polymethylmethacrylate is considered the most prevalent bone cement base material. Most fractures that occur during function are due to its weakness and lack of mechanical strength. The apparent limitations of PMMA are insufficient ductility, strength, and viscoelastic behavior. The current study aims to strengthen and improve PMMA bone cement properties by adding modified TiO2 nanoparticles (m-TiO2 NPs). Therefore, the silane coupling agent modified the neat TiO2 NPs and then added different ratios (0.5, 1, 1.5, and 2 wt %) to the PMMA bone cement. Fourier transform infrared spectroscopy (FTIR) technique used to investigate the modification process and specify the bonding type between m-TiO2NPs and the PMMA bone cement matrix. The SEM technique is used to study the morphologies of the prepared samples. Properties such as tensile strength, compression strength, modulus of elasticity, and impact strength, were measured. Results proved the successes of TiO2NPs modification by silane coupling agent and the absence of any chemical bonding between this modified filler and other PMMA bone cement ingredients. The mechanical properties increased by m-TiO2NPs addition up to 1 wt% ratio then decreased. The morphology results supported the mechanical properties trends.

Advanced G-MPS-PMMA Bone Cements: Influence of Graphene Silanisation on Fatigue Performance, Thermal Properties and Biocompatibility.

The incorporation of well-dispersed graphene (G) powder to polymethyl methacrylate (PMMA) bone cement has been demonstrated as a promising solution to improving its mechanical performance. However, two crucial aspects limit the effectiveness of G as a reinforcing agent: (1) the poor dispersion and (2) the lack of strong interfacial bonds between G and the matrix of the bone cement. This work reports a successful functionalisation route to promote the homogenous dispersion of G via silanisation using 3-methacryloxypropyltrimethoxy silane (MPS). Furthermore, the effects of the silanisation on the mechanical, thermal and biocompatibility properties of bone cements are presented. In comparison with unsilanised G, the incorporation of silanised G (G_MPS1 and G_MPS2) increased the bending strength by 17%, bending modulus by 15% and deflection at failure by 17%. The most impressive results were obtained for the mechanical properties under fatigue loading, where the incorporation of G_MPS doubled the Fatigue Performance Index (I) value of unsilanised G-bone cement—meaning a 900% increase over the I value of the cement without G. Additionally, to ensure that the silanisation did not have a negative influence on other fundamental properties of bone cement, it was demonstrated that the thermal properties and biocompatibility were not negatively impacted—allowing its potential clinical progression.

Effect of barium sulfate surface treatments on the mechanical properties of acrylic bone cements

Although current commercial acrylic bone cements have been used successfully in total joint replacement surgery for over five decades, some further improvement are being investigated to cope with cement failure, one approach is surface modification of BaSO4 particles to improve its interfacial adhesion with the polymeric matrix in acrylic bone cements formulations. In this article, BaSO4 particles were modified by different surface treatments. The first of them involved the use of 3-(trimethoxysilyl)propyl methacrylate as a coupling agent; in the second, the radiopaque particles were exposed to oxygen plasma at power levels of 15 and 70 W, followed by MPS coupling agent and the last one consisted in exposing the radiopaque particles to methyl methacrylate (MMA) plasma. Mechanical properties of the bone cements prepared with modified BaSO4 particles were improved due to its higher dispersion degree in polymeric matrix.

Biological and mechanical properties of bone cement with nanoparticles - in vitro and in vivo research

Biological and mechanical properties of bone cement with nanoparticles - in vitro and in vivo research

Mechanical, elution, and antibacterial properties of simplex bone cement loaded with vancomycin

Prosthetic joint infection (PJI) is one of the most devastating failures in total joint replacement (TJR). Infections are becoming difficult to treat due to the emergence of multi-drug resistant bacteria. These bacteria produce biofilm on the implant surface, rendering many antibiotics ineffective by compromising drug diffusion and penetration into the infected area. With the introduction of new antibiotics there is a need to create benchmark data from the traditional antibiotic loaded bone cements. Vancomycin, one of the commonly used antibiotics, shows activity against Methicillin-resistant Staphylococcus aureus (MRSA) and S.epidermidis. In our study, vancomycin added to bone cement was evaluated for elution properties, antimicrobial properties, and mechanical properties of the bone cement. Vancomycin at five different loading masses (0.125, 0.25, 0.5, 1.0 and 2.0 g) was added to 40 g of Simplex™ P cement. Addition of vancomycin affected the mechanical properties and antimicrobial activity with significant differences from controls. Flexural and compression mechanical properties were compromised with added vancomycin. The flexural strength of samples with added vancomycin of 0.5 g and greater were not greater than ISO 5833 minimum requirements. 2.0 g of vancomycin added to bone cement was able to eliminate completely the four bacterial strains tested. 2.0 g of vancomycin also showed the highest mass elution from the cement over a 60-day period. Given the reduced flexural strength in samples with 0.5 g and greater of added vancomycin and the inability of vancomycin in amounts less than 2.0 g to eliminate bacteria, this study did not find an ideal amount of vancomycin added to Simplex™ P that meets both strength and antibacterial requirements.

Effect of Physiological Fluids Contamination on Selected Mechanical Properties of Acrylate Bone Cement.

This study analyses the degradation rate of selected mechanical properties of bone cement contaminated with human blood and saline solution. During the polymerisation stage, the PMMA cement specimens were supplemented with the selected physiological fluids in a range of concentrations from 0% to 10%. The samples were then subjected to the standardised compression tests, as per ISO 5833: 2002, and hardness tests. The obtained results were analysed statistically to display the difference in the degradation of the material relative to the degree of contamination. Subsequently, numerical modelling was employed to determine the mathematical relationship between the degree of contamination and the material strength degradation rate. The introduction of various concentrations of contaminants into the cement mass resulted in a statistically significant change in their compressive strength. It was shown that the addition of more than 4% of saline and more than 6% of blood (by weight) causes that the specimens exhibit lower strength than the minimum critical value of 70 MPa, specified in the abovementioned International Standard. It was further revealed that the cement hardness characteristics degraded accordingly. The mathematical models showed a very good fit with the results from the experiments: The coefficient of determination R2 was 0.987 in the case of the linear hardness model for blood and 0.983 for salt solution; secondly, the values of R2 for the third-degree polynomial model of compressive strength were 0.88 for blood and 0.92 for salt. From the results, it can be seen that there is a quantitative/qualitative relationship between the contamination rate and the drop in the tested mechanical characteristics. Therefore, great effort must be taken to minimise the contact of the bone cement with physiological fluids, which naturally occur in the operative field, particularly when the material cures, in order to prevent the cement material strength declining below the minimum threshold specified in the ISO standard.

Improving osteogenesis of calcium phosphate bone cement by incorporating with manganese doped β-tricalcium phosphate.

Lack of osteogenic capacity limits the bone repair effect of calcium phosphate cement (CPC). In present work, bivalent manganese ion (Mn2+) doped β-tricalcium phosphate (Mn-TCP) was incorporated into CPC to enhance its osteogenic ability. The incorporation of Mn-TCP promoted the hydration reaction of CPC. The presence of Mn2+ made the hydration products finer. When adding 10wt% Mn-TCP in CPC (Mn-CPC-1), the setting time of CPC was shortened, whereas the strength and injectability were not changed. Mouse Bone marrow mesenchymal stem cells (mBMSCs) on Mn-CPC-1 and CPC with 20wt% Mn-TCP (Mn-CPC-2) presented better adhesion and spreading behaviors. Besides, Mn-CPC-1 promoted the gene levels of ALP, Col-I and OC while Mn-CPC-2 promoted the gene levels of Runx2 and OC. Cellular behaviors were related to two points: one was the increase of adsorption capacity of proteins (e.g. BSA) after changing the surface properties of bone cements; and the other was the biological role of Mn2+ released from CPC in osteogenesis. All the results indicated that CPC incorporated with 10wt% Mn-TCP has good osteogenesis and proper physicochemical properties, which will be a prospective biomaterial applying in the area of bone regeneration.

Thermal evaluation of the injectable liquid metal bone cement in orthopedic treatment

The thermophysical properties of bone cement are important parameters for its application in the orthopedic treatment. This article focused on the thermal evaluation of the low-melting-point metal (BiInSn alloy), which has been proved to be an excellent bone cement. Firstly, the basic thermophysical properties of BiInSn alloys with different melting points were measured. Secondly, 15 fresh porcine femurs placed in the saline bath, bone cements with different melting points and amounts were injected into the bone cavities, respectively. Thermocouples were used to measure the temperature changes of the bone-cement interface and peripheral bone tissue. The possibility of thermal necrosis was evaluated. Moreover, a three-dimensional human knee model was built to numerically assess the effects of thermal parameters, such as melting point and latent heat on tissue temperature distribution. All the experimental and numerical results implied the heat distribution in the tissue depended on the thermal performances of liquid metal bone cement (LMBC). For LMBC of the same melting point, with increased amounts, the damage to the bone tissue is more severe, while for the same amount of different melting point LMBCs, with the higher melting point, which will lead to more serious damage to the tissue. Also, higher latent heat of LMBC has distinct longer solidification process, which may cause irreversible damage to surrounding tissues. Therefore, in the future, for different clinical surgery needs, the appropriate liquid metal bone cement can be obtained by adjusting the thermal parameters.

The Effect of Surface Modification of Ti13Zr13Nb Alloy on Adhesion of Antibiotic and Nanosilver-Loaded Bone Cement Coatings Dedicated for Application as Spacers.

Spacers, in terms of instruments used in revision surgery for the local treatment of postoperative infection, are usually made of metal rod covered by antibiotic-loaded bone cement. One of the main limitations of this temporary implant is the debonding effect of metal–bone cement interface, leading to aseptic loosening. Material selection, as well as surface treatment, should be evaluated in order to minimize the risk of fraction and improve the implant-cement fixation the appropriate manufacturing. In this study, Ti13Zr13Nb alloys that were prepared by Selective Laser Melting and surface treated were coated with bone cement loaded with either gentamicin or nanosilver, and the effects of such alloy modifications were investigated. The SLM-made specimens of Ti13Zr13Nb were surface treated by sandblasting, etching, or grounding. For each treatment, Scanning Electron Microscope (SEM), contact profilometer, optical tensiometer, and nano-test technique carried out microstructure characterization and surface analysis. The three types of bone cement i.e., pure, containing gentamicin and doped with nanosilver were applied to alloy surfaces and assessed for cement cohesion and its adhesion to the surface by nanoscratch test and pull-off. Next, the inhibition of bacterial growth and cytocompatibility of specimens were investigated by the Bauer-Kirby test and MTS assay respectively. The results of each test were compared to the two control groups, consisting of commercially available Ti13Zr13Nb and untreated SLM-made specimens. The highest adhesion bone cement to the titanium alloy was obtained for specimens with high nanohardness and roughness. However, no explicit relation of adhesion strength with wettability and surface energy of alloy was observed. Sandblasting or etching were the best alloys treatments in terms of the adhesion of either pure or modified bone cements. Antibacterial additives for bone cement affected its properties. Gentamicin and nanosilver allowed for adequate anti-bacterial protection while maintaining the overall biocompatibility of obtained spacers. However, they had different effects on the cement’s adhesive capacity or its own cohesion. Furthermore, the addition of silver nanoparticles improved the nanomechanical properties of bone cements. Surface treatment and method of fabrication of titanium affected surface parameters that had a significant impact on cement-titanium fixation.

Effect of different mixing modes of enoxaparin sodium on biomechanics of bone cement

Objective To observe the biomechanical effects of enoxaparin sodium added to bone in different mixing modes. Methods The enoxaparin sodium for injection was mixed with polymethylmethacrylate (PMMA) bone according to different dosages and different mixing methods. Group A was used as blank control group without enoxaparin sodium. Groups B (8 000 AxaIU), C (16 000 AxaIU) and D (24 000 AxaIU) served as control groups in a powder mixture. Groups E (8 000 AxaIU), F (16 000 AxaIU) and G (24 000 AxaIU) served as experimental groups. The enoxaparin sodium for injection was dissolved and added to the PMMA bone cement. Under the environment of sterility, temperature (23±1) ℃, relative humidity higher than 40% (operating room environment), according to the international standard ISO5833: 2002 Implants for surgery-Acrylic resin cement regulations, bone cylinder specimens and cuboid specimens were prepared. After measurement and X-ray irradiation, 5 specimens of each group were selected, and the compressive strength, flexural strength and flexural modulus were measured on an electronic material universal testing machine. Results The compressive strength, flexural strength and flexural modulus in groups E, F and G were significantly lower than those in the control groups (t=12.731, 41.646, 3.128, P<0.05). The lowest values were (57.17±1.15) MPa, (67.93± 0.55) MPa, and (19.2± 0.114) GPa respectively. Conclusion The addition of enoxaparin sodium to PMMA bone in a liquid mixture can significantly reduce the biomechanical properties of bone cement. Key words: Polymethylmethacrylate bone cement; Enoxaparin sodium; Biomechanics

Biomechanical testing of bioactive bone cements – a comparison of the impact of modifiers: antibiotics and nanometals

Apart from its bone filler and fracture stabilizing function, bone cement can be used as a carrier of bioactive substances, and such modified bone cement can protect the implant against microorganisms, treat local infections and combat bacteria introduced during the surgical procedure. In this paper, the effects of modifying antibiotics and nanosilver on the biomechanical properties of bone cement were examined. The following tests were carried out: curing time, wettability, microhardness, porosity, microstructure and mechanical tests. Additionally, preliminary tests on bactericidal properties in the form of bacterial growth inhibition zones were conducted. No negative impact of bioactive modifications on cement properties was observed, except for bending strength in bone cement with antibiotics. Unmodified bone cement and nanosilver-loaded cement fulfilled all of the requirements specified in the standards and assumptions regarding their biofunctionality. Antibiotic-loaded cement provided a greater range of bioactivity. Attention should be paid to the potential effects of nanosilver as regards the lack of bacterial resistance, prevention and destruction of biofilm structure and length of bioactivity. Bone cement containing nanometals can serve as an alternative to the bioactive bone cements that are currently in use.

A Study of Mechanical Properties of Bone Cement Containing Micro- and Nano- Hydroxyapatite Particles

In this research, mechanical properties of bone cement containing micro-and nanohydroxyapatite (HAp) particles were studied. The bone cement was prepared from mixing between polymethyl methacrylate (PMMA) and methyl methacrylate (MMA). Hydroxyapatite powder was prepared from bovine bone. The bone was heated in hot water at 200 oc for the elimination of tissue, after which the bone was dried and calcined at 800 oc for 3 hrs. The calcined bone than was crushed into powder and ball-milled for 24 hrs. The micro-HAp particle was then obtained. The micro particles were then further milled employing the Vibro-milling machine for 2 hrs. The micro-and nanoHAp sizes are about 0.5 μm and 140 nm, respectively. The both size powders were treated with γ-methacrylic-propyl-tri-methoxy silane. The acetic acid was added to control the pH of the solution, until it reached 2.9 before they were mixed into the bone cement with equally wt%. The mixture was casted using the 304 stainless steel mold in order to obtain a cylindrical shape. The low vacuum scanning electron microscope (LV-SEM) and x-ray diffractometer (XRD) were employed to characterize the samples. The porosity of PMMA could be reduced by HAp particle additives. From compressive strength test, it was found that the mixture of bone cement and nanoHAp particle has shown higher compressive strength than pure PMMA bone cement that affected by porosity reduction and force distribution by HAp particles.

Bone preserving techniques for explanting the well-fixed cemented acetabular component

BackgroundRemoval of a well-fixed, cemented acetabular component at the time of revision hip surgery can be complex. It is essential to remove the implant and cement mantle in a timely fashion while preserving bone stock and osseous integrity. The biomechanical properties of polymethylmethacrylate cement and polyethylene can be utilised to aid with the removal of well cemented implants which are often harder than the surrounding bone. While removal of loose components may be relatively straightforward, the challenge for the revision arthroplasty surgeon often involves the removal of well-fixed implants. Here, we present three established techniques for the removal of a well-fixed cemented acetabular component and one novel modification we have described before. MethodWe collate and review four techniques for removing well-fixed cemented acetabular implants that utilise the different biomechanical properties of bone cement and polyethylene. These techniques are illustrated with a photographic series utilising saw bones. A step-by-step approach to our new technique is shown in photographs, both in the clinical setting and with a “Sawbone”. This is accompanied by a clinical video that details the surgical technique in its entirety. ResultsThese techniques utilise different biomechanical principles to extract the acetabular component. Each technique has advantages and disadvantages. Our new technique is a simplification of a previously published extraction manoeuvre that utilises tensile force between cement and the implant to remove the polyethylene cup. This is a safe and reproducible technique in patients with a well-fixed cemented acetabular implant. ConclusionUnderstanding the biomechanical properties of polymethylmethacrylate bone cement and polyethylene can aid in the safe removal of a well-fixed cemented acetabular component in revision hip surgery. The optimal technique for removal of a cemented acetabular component varies depending on a number of patient and implant factors. This summary of the available techniques will be of interest to revision arthroplasty surgeons.

Physical, mechanical, chemical and thermal properties of nanoscale graphene oxide-poly methylmethacrylate composites

The purpose of this laboratory study was to formulate and characterize the graphene oxide-poly(methyl methacrylate) resin composite with an intended use as bone cement. Graphene oxide was fabricated through ultrasonication route. The autopolymerization resin (Eco Cryl Cold, Protechno, Vilamalla Girona, Spain) was used to prepare the specimens of required dimensions for different testing parameters. The control group (C-group) was prepared as such. However, for GO1-group, 0.024 wt/wt.-% of graphene oxide was incorporated in a resin matrix and GO2-group was a composite with 0.048 wt/wt.-% of graphene oxide in a resin matrix. TEM examination of graphene oxide sheets demonstrated them in the range of ∼500 nm to ∼2 µm. The mechanical properties were characterized using three-point bending and wear resistance, while material properties were assessed through transmission electron microscope, scanning electron microscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, differential scanning calorimetry and thermo-gravimetric analysis. The results suggest that 0.024 wt/wt.-% and 0.048 wt/wt.-% of loading of GO have no effect on the physiochemical characteristics. However, thermal characteristics might slightly be improved. According to the analysis of variance results ( p &lt; 0.05, n = 5), wear resistance and bending strength of both GO1 and GO2 groups significantly improved compared to C-group. The bending strength of GO2 improved to 87.0 ± 7.2 MPa from 65.9 ± 11.5 MPa of C-group. Scanning electron microscopy examination of the fractured surface demonstrated granule like structure where the graphene oxide sheets might be covered inside PMMA. The use of GO-PMMA composites favorably enhances the mechanical properties of bone cement.

Analysis of the properties of bone cement with respect to its manufacturing and typical service lifetime conditions

This paper analyses the impact of exposure to Ringer’s solution, an isotonic solution relative to the body fluids, on the strength of bone cement. Research was conducted in order to determine moisture uptake and strength degradation. Prior to mechanical tests, the samples were seasoned in the solution simulating the human body conditions and subsequently measured to determine their increase in weight. Samples were then tested, using MTS Bionix testing system, for compressive strength according to ISO Standard. The data obtained from the measurements allowed to develop a statistical model for predicting cement absorption rate over a longer period of time. Compression strength of both seasoned and unseasoned samples was measured over time. The results were analysed statistically to show an effect of seasoning on cement strength. Cement samples show moderate moisture uptake over time, together with some decrease of compressive strength. Correlation between two above mentioned, measured factors was proven and linear model prepared. Using obtained models, one can estimate the cement strength and moisture uptake over time.

Synthesis of imidazolium-containing mono-methacrylates as polymerizable antibacterial agents for acrylic bone cements

With the aim to prepare antibacterial acrylic bone cements, a series of imidazolium-containg mono-methacrylates with N-alkyl chain length varied from 10 to 18 (MEIM-x) were synthesized as polymerizable antibacterial agents through a two-step reaction. The structures of the monomers were confirmed by 1H NMR. Methyl methacrylate in the liquid compoent of cements was partially replaced by MEIM-x to prepare bone cements with 5wt% of MEIM-x. Properties of prepared cements like antibacterial activity, doughing time, curing parameters including maximum temperature (Tmax) and setting time (tset), flexual strength (FS) and modulus (FM), compressive strength (CS) and fluid uptake (FU) in Ringer's solution were investigated. Acrylic bone cement without any MEIM-x was used as control. Compared with the control cement, MEIM-x-containing cements had shorter doughing time, lower Tmax, same or longer tset, and higher FU. Though MEIM-x could endow cements with strong antibacterial activity, it could reduce mechanical properties of bone cements. Therefore, further study should be taken to optimize the content of MEIM-x in cement which could supply sufficient antibacterial activity and maintain mechanical performance.

Microencapsulation of rifampicin: A technique to preserve the mechanical properties of bone cement.

Two-stage exchange with antibiotic-loaded bone cement spacers remains the gold standard for chronic periprosthetic joint infection (PJI). Rifampicin is highly efficient on stationary-phase staphylococci in biofilm; however, its addition to PMMA to manufacture spacers prevents polymerization and reduces mechanical properties. Isolation of rifampicin during polymerization by microencapsulation could allow manufacturing rifampicin-loaded bone cement maintaining elution and mechanical properties. Microcapsules of rifampicin with alginate, polyhydroxybutyratehydroxyvalerate (PHBV), ethylcellulose and stearic acid (SA) were synthesized. Alginate and PHBV microcapsules were added to bone cement and elution, compression, bending, hardness, setting time and microbiological tests were performed. Repeated measures ANOVA and Bonferroni post-hoc test were performed, considering a p < 0.05 as statistical significance. Bone cement specimens containing alginate microcapsules eluted more rifampicin than PHBV microcapsules or non-encapsulated rifampicin over time (p < 0.012). Microencapsulation of rifampicin allowed PMMA to preserve mechanical properties in compression and bending tests. Cement with alginate microcapsules showed similar behavior in hardness tests to control cement over the study period (73 ± 1.68HD ). PMMA with alginate microcapsules exhibited the largest zones of inhibition in microbiological tests. Statistically significant differences in mean diameters of zones of inhibition between PMMA loaded with alginate-rifampicin (p = 0.0001) and alginate-PHBV microcapsules (p = 0.0001) were detected. Rifampicin microencapsulation with alginate is the best choice to introduce rifampicin in PMMA preserving mechanical properties, setting time, elution, and antimicrobial properties. The main applicability of this study is the opportunity for obtaining rifampicin-loaded PMMA by microencapsulation of rifampicin in alginate microparticles, achieving high doses of rifampicin in infected tissues, increasing the successful of PJI treatment. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:459-466, 2018.

Size and boundary effects on notch tensile strength and fracture properties of PMMA bone cement

Poly (methyl methacrylate) bone cement is widely used for anchoring total joint replacements. In such an application, tensile and fracture properties of the cement are particularly important as they have strong implications for the stability of the implant in the bone bed and, hence, its life. Being a quasi-brittle material, it is to be expected that any mechanical property of bone cement would be size-dependent. This issue has not been addressed in the literature. In the present work, tests using modified wedge-splitting specimens were carried out to determine the size and boundary effects on the notch tensile strength (σNT) and on two fracture parameters, namely, specific fracture energy (Gf), and characteristic length based on the notch tensile strength (lchspl) of a widely used approved brand, Palacos® R. Size and boundary effects, of varying magnitudes, on each of these properties were found. For example, 1) for geometrically-similar specimens (specimen height (W) was varied from 15 mm to 36 mm but ratio of length of the starter crack (a) to W was fixed), the general trend was marked decrease in σNT with increase in W for a given a/W; and 2) for identical-sized specimens (W was fixed but a/W was varied from 0.06 to 0.81), the general trend was moderate decrease in Gf with increase in a/W for a given W. A validated boundary effect model presented in the literature and results from some of the specimens used in the present experimental work were used to compute the size-independent specific fracture energy and transition ligament length of the cement brand to be 2096 N m−1 and 4 mm, respectively.

Synthesis and properties of bone cement based on poly(methyl methacrylate) reinforced by organo-clay

Poly(methyl methacrylate) (PMMA) and nanocomposites PMMA/nano-clay were widely applied in many different fields. Bone cement is one of the important application which makes artificial bones and joints. The purpose of our study is the improvement of properties of PMMA. Therefore, organo-clay modified by polyethylene oxide (PEO) was used to reinforce the PMMA resin. In order to increase the interaction between PMMA and organo-clay, the in-situ emulsion polymerization has been used to synthesize nanocomposites. Accordingly, nanocomposites with the weight percentage of organo-clay of 1 %, 3 %, 5 %, 7 % increase the thermal and mechanical properties compared to PMMA. These were evidence of the good interaction between PMMA and organo-clay. In addition, PMMA/5 % MMT-PEO nanocomposite is also synthesized by in-situ Pickering emulsion polymerization [3] to compare with the method of emulsion polymerization.

An in vitro experimental study on the physical and elution properties of PMMA bone cement loaded with rifampicin, isoniazid, pyrazinamide and moxifloxacin

Objective To investigate the feasibility of Antituberculotic-loaded bone cement (ATLBC) prepared by mixing the anti-TB drugs Rifampicin (RFP), Isoniazid (INH), Pyrazinamid (PZA), Moxifloxacin (MFX) with Palacos R PMMA bone cement in Total Joint Arthroplasty treatment for Joint Tuberculosis. Methods Forty grams of Palacos R bone cement powder without antibiotics was mixed with 1 or 2 grams of RFP, INH, PZA and MFX respectively. According to ISO 5833:2002 standard, 8 groups of ATLBC standard test specimen were prepared as experiment group and Palacos R PMMA bone cement without antibiotics was prepared as control group. Physical properties (such as the average dough time, curing time, maximum temperature), mechanical strength (such as the compressive strength, the bending resistance strength, the modulus of elasticity) and the concentrations of eluant drug in different time points of ATLBC were detected. Results In RFP (1 g), RFP (2 g), INH (1 g) and INH (2 g) group, the average dough time and curing time were longer than those in control group, which exceeded the standard scope of ISO, while the average maximum temperature was significantly lower than that in control group. The INH (1 g) group and INH (2 g) group hardened after mixing for 14 days. The RFP (1 g) group and RFP (2 g) group hardened after mixing for 30 days. Twenty minutes after mixing and hardening, the compressive strength, bending resistance strength and modulus of elasticity were significantly lower than the specified values of ISO standard. The physical properties and mechanical strength in PZA (1 g) group, PZA (2 g) group, MFX (1 g) group, MFX (2 g) group and control group were in accordance with the specified values of ISO standard, and they hardened after 20 minutes. In RFP (1 g) group, RFP (2 g) group, INH (1 g) group, INH (2 g) group, PZA (1 g) group, PZA (2 g) group, MFX (1 g) group and MFX (2 g) group, the concentration of eluant could maintain for 3 days, 7 days, 90 days, 90 days, 45 days, 60 days, 60 days and 60 days respectively. Conclusion RFP and INH mixing with Palacos R PMMA bone cement can hinder the aggregation of bone cement so they are unsuitable for preparing ATLBC. PZA and MFX mixing with Palacos R PMMA bone cement do not affect the physical properties of bone cement, with excellent mechanical strength and elution properties. Because the minimal inhibitory concentration of PZA is higher and its antimicrobial activity maintains shorter time, while MFX maintains longer time in antimicrobial activity, it's more suitable for the preparation of ATLBC. Key words: Rifampin; Isoniazid; Pyrazinamide; Polymethyl methacrylate; Bone cements; Delayed-action preparations; Biomechanics