Mechanical Properties Of Bone Cement Research Articles

Effects of hexagonal boron nitride on mechanical properties of bone cement (Polymethylmethacrylate).

The aim of this study was to investigate the effects of adding hexagonal boron nitride at four different concentrations to polymethylmethacrylate (PMMA) bone cement, which is commonly used in orthopedic surgeries, on the mechanical properties and microarchitecture of the bone cement. The study included an unaltered control group and groups containing four different concentrations (40 g of bone cement with 0.5 g, 1 g, 1.5 g, 2 g) of hexagonal boron nitride. The samples used for mechanical tests were prepared at 20±2ºC in operating room conditions, using molds in accordance with the test standards. As a result of the tests, the pressure values at which the samples deformed were determined from the load-deformation graphs, and the megapascal (MPa) values at which the samples exhibited strength were calculated. The samples with 0.5 g boron added to the bone cement had significantly increased mechanical strength, particularly in the compression test. In the group where 2 g boron was added, it was noted that, compared to the other groups, the strength pressure decreased and the porosity increased. The porosity did not change particularly in the group where 0.5 g boron was added. Our study results demonstrate that adding hexagonal boron nitride (HBN) to bone cement at a low concentration (0.5 g / 40 g PPMA) significantly increases the mechanical strength in terms of MPa (compression forces) without adversely affecting porosity. However, the incorporation of HBN at higher concentrations increases porosity, thereby compromising the biomechanical properties of the bone cement, as evidenced by the negative impact on compression and four-point bending tests. Boron-based products have gained increased utilization in the medical field, and HBN is emerging as a promising chemical compound, steadily growing in significance.

Enhancing Bone Cement Efficacy with Hydrogel Beads Synthesized by Droplet Microfluidics

Effective filling materials, typically bone cements, are essential for providing mechanical support during bone fracture treatment. A current challenge with bone cement lies in achieving continuous drug release and forming porous structures that facilitate cell migration and enhance osteoconductivity. We report a droplet microfluidics-based method for synthesizing uniform-sized gelatin hydrogel beads. A high hydrogel concentration and increased crosslinking levels were found to enhance drug loading as well as release performance. Consequently, the droplet microfluidic device was optimized in its design and fabrication to enable the stable generation of uniform-sized droplets from high-viscosity gelatin solutions. The size of the generated beads can be selectively controlled from 50 to 300 μm, featuring a high antibiotic loading capacity of up to 43% dry weight. They achieve continuous drug release lasting more than 300 h, ensuring sustained microbial inhibition with minimal cytotoxicity. Furthermore, the hydrogel beads are well suited for integration with calcium phosphate cement, maintaining structural integrity to form porous matrices and improve continuous drug release performance. The uniform size distribution of the beads, achieved through droplet microfluidic synthesis, ensures predictable drug release dynamics and a measurable impact on the mechanical properties of bone cements, positioning this technology as a promising enhancement to bone cement materials.

INFLUENCE OF FLUID UPTAKE ON THE MECHANICAL AND THERMAL PROPERTIES OF PMMA-BASED BONE CEMENT

According to the latest report from the German Arthroplasty Registry, aseptic loosening is the primary cause of implant failure following primary hip arthroplasty. Osteolysis of the proximal femur due to the stress-shielding of the bone by the implant causes loss of fixation of the proximal femoral stem, while the distal stem remains fixed.Removing a fixed stem is a challenging process. Current removal methods rely on manual tools such as chisels, burrs, osteotomes, drills and mills, which pose the risk of bone fracture and cortical perforation. Others such as ultrasound and laser, generate temperatures that could cause thermal injury to the surrounding tissues and bone. It is crucial to develop techniques that preserve the host bone, as its quality after implant removal affects the outcome of a revision surgery.A gentler removal method based on the transcutaneous heating of the implant by induction is proposed. By reaching the glass transition temperature (TG) of the periprosthetic cement, the cement is expected to soften, enabling the implant to be gently pulled out. The in-vivo environment comprises body fluids and elevated temperatures, which deteriorate the inherent mechanical properties of bone cement, including its TG. We aimed to investigate the effect of fluid absorption on the TG (ASTM E2716-09) and Vicat softening temperature (VST) (ISO 306) of Palacos R cement (Heraeus Medical GmbH) when dry and after storage in Ringer's solution for up to 8 weeks.Samples stored in Ringer's solution exhibited lower TG and VST than those stored in air. After 8 weeks, the TG decreased from 95.2°C to 81.5°C in the Ringer's group, while the VST decreased from 104.4°C to 91.9°C. These findings will be useful in the ultimate goal of this project which is to design an induction-based system for implant removal.Acknowledgements: Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – SFB/TRR-298-SIIRI – Project-ID 426335750

Statistical distribution of micro and macro pores in acrylic bone cement- effect of amount of antibiotic content

Aseptic loosening due to mechanical failure of bone cement is considered to be a leading cause of revision of joint replacement systems. Detailed quantified information on the number, size and distribution pattern of pores can help to obtain a deeper understanding of the bone cement's fatigue behavior. The objective of this study was to provide statistical descriptions for the pore distribution characteristics of laboratory bone cement specimens with different amounts of antibiotic contents. For four groups of bone cement (Palacos) specimens, containing 0.3, 0.6, 1.2 and 2.4 wt/wt% of telavancin antibiotic, seven samples per group were micro computed tomography scanned (38.97 μm voxel size). The images were first preprocessed in Mimics and then analyzed in Dragonfly, with the level of threshold being set such that single-pixel pores become visible. The normalized pore volume data of the specimens were then used to extract the logarithmic histograms of the pore densities for antibiotic groups, as well as their three-parameter Weibull probability density functions. Statistical comparison of the pore distribution data of the antibiotic groups using the Mann–Whitney non-parametric test revealed a significantly larger porosity (p < 0.05) in groups with larger added antibiotic contents (2.4 and 0.6 wt/wt% vs 0.3 wt/wt%). Further analysis revealed that this effect was associated with the significantly larger frequency of micropores of 0.1–0.5 mm diameter (p < 0.05) in groups with larger antibiotic content (2.4 wt/wt% vs and 0.6 and 0.3 wt/wt%), implying that the elution of the added antibiotic produces micropores in this diameter range mainly. Based on this observation and the fatigue test results in the literature, it was suggested that micropore clusters have a detrimental effect on the mechanical properties of bone cement and play a major role in initiating fatigue cracks in highly antibiotic added specimens.

Tunicate cellulose nanocrystals reinforced modified calcium sulfate bone cement with enhanced mechanical properties for bone repair

Considering the poor mechanical properties of bone cement, its practical application has always been limited. In this study, we introduced tunicate cellulose nanocrystals (TCNCs) into calcium sulfate bone cement for the first time, and multiple enhanced composite bone cement was prepared by the condensation reflux method. Firstly, high-strength modified calcium sulfate hemihydrate (CSH) bone cement was successfully prepared by using tartaric acid, a crystal modifier with a chiral structure. Secondly, the inclusion of TCNCs not only exhibited significant reinforcement and toughening effects but also stimulated the adhesion, proliferation, and differentiation of related osteoblasts. Furthermore, TCNCs encapsulated the CSH particles, overcoming the limitations of excessive degradation rates in bone cement and enabling sustained release of Ca2+, promoting the healing of bone defects. Overall, this study presents novel ideas and methodologies for designing bone cement with exceptional performance. It also provides a new platform for the development of bone tissue engineering and is expected to become a new type of bone regeneration material. The utilization of oceanic resources in this context holds high-value potential, alleviating environmental burdens and providing clinically applicable bone tissue repair materials with broad application prospects.

Targeting staphylococcal bone infections

A novel quinolone antibiotic was developed by Shiladitya Sengupta and colleagues using molecular-docking simulation, and one lead compound, VCD-077, was selected based on this strategy.1 Antimicrobial resistance is increasing, driven by widespread antibiotic overuse in medical and agricultural settings.2 Paradoxically, despite the urgent need to develop a new generation of antibiotics, their marketability is suppressed, partly because the new antibacterial drug may quickly develop new resistance and the development of new antibiotics is sluggish.3, 4 The ideal next-generation antibiotic should demonstrate excellent activity against drug-resistant bacteria, good biosafety, flexible drug delivery, and the ability to retard the development of resistance. In this regard, recently researchers have focused on developing novel antibiotics by improving drug performance, availability, targeted enrichment, and reducing systemic toxicity. Reporting in Nature Biomedical Engineering, Shiladitya Sengupta and colleagues now show that VCD-077 screened by molecular-docking simulations exhibits excellent activity against drug-resistant bacteria and its biofilms, reduces the development of bacterial resistance and is compatible with bone cement for local delivery and treatment of staphylococcal bone infections in rats (Figure 1).1 Bone infections are rising rapidly due to accidental fractures and the global aging population.5 Sengupta and co-authors designed a series of quinolone antibiotics using molecular-docking simulation. They selected VCD-077 from 17 candidate antibiotics, which can effectively against clinical drug-resistant staphylococcal and retard the development of resistance. The minimal inhibitory concentration (MIC) of ciprofloxacin, Staphylococcus aureus sensitive antibiotics, increased stepwise to 64.0 μg/ml by the 20th passage to S. aureus. While S. aureus were still sensitive to VCD-077 even at the 28th passage. Specifically, VCD-077 is potent against S. aureus and Staphylococcus epidermidis biofilms because it is a weak acid with a single pKa of 5.8, that is, it still maintains antibacterial activity at pH 5.5–7.4. In contrast, gentamicin lost part of its activity at acid pH 5.5. Therefore, VCD-077 has a unique advantage in the prevailing weakly acidic infected bone environment. Notably, VCD-077 is physicochemically compatible with polymethylmethacrylate bone cement, exhibits desired pharmacokinetics without loss of mechanical properties of bone cement. VCD-077-impregnated bone cement showed more powerful anti-infective activity compared with either FDA-approved rifampin or gentamicin-impregnated bone cement. Overall, the authors show that VCD-077-impregnated bone cement could be used as rational next-generation drugs or coatings to treat bone infections. The high efficacy of Sengupta and co-authors' VCD-077-impregnated bone cement suggests that flexible local administration can be achieved at ideal safe concentration, and is effective against resistant strains, as well as delaying the development of new resistance. However, before VCD-077-impregnated bone cement can be considered for the treatment of clinical bone infection, three main challenges were compelled to be discussed. First, the authors used rodents in this experiment, which may be differences between the efficacy of antibiotics-impregnated bone cement in rodents and human bones. Studies using larger animal infection models (such as pigs and monkeys) would employ to corroborate the impressive antimicrobial activity in rat models. Second, significant biosafety assessment under good laboratory practice guidelines should be performed. And third, new antibiotic development should focus on specific screening molecules and combinations with emerging nanoparticle-based delivery systems that can target both resistant and persistent bacterial populations.6 Developing novel antibacterial agent delivery systems to improve the bioavailability of antibiotics is a promising strategy for increasing the lifespan of newly developed antibiotics. Integration of such novel antibiotics and combinations into nanoparticle-based delivery systems or coating implants might transform the landscape of infectious diseases. Drafting the article: Zhang Xiangchun. Revising the manuscript: Xulin Hu and Hongping Chen. All authors have read and approved the final manuscript This research was supported by the National Key Research and Development Program of China (2021YFD1601102), Central Public-interest Scientific Institution Basal Research Fund (No. Y2022QC24), and Innovative Program of Chinese Academy of Agricultural Sciences (CAAS-ASTIP-2021-TRI, CAAS-ZDRW202011). The authors declare no conflict of interest. Not applicable. Not applicable.

Modification and evaluation of diatrizoate sodium containing polymethyl methacrylate bone cement.

Polymethyl methacrylate (PMMA) bone cement is now widely used in percutaneous vertebro plasty (PVP) and percutaneous kyphoplasty (PKP). However, studies showed that the radiopacifiers (zirconia, barium sulfate, etc.) added to PMMA will have a negative impact on its use, e.g. barium sulfate will weaken the mechanical properties of bone cement and lead to bone absorption and aseptic loosening. Iodine is an element existing in the human body and has good imaging performance. Iodine contrast agent has been used in clinic for many years and has abundant clinical data. Therefore, using iodine instead of barium sulfate may be a promising choice. In this paper, the effect of different content of diatrizoate sodium (DTA, C11H8I3N2NaO4) on the properties of PMMA was studied and compared with the traditional PMMA bone cement containing 30 wt% barium sulfate. The mechanical properties, setting properties, radiopacity, and biocompatibility of bone cement were evaluated. The compressive strength of PMMA bone cement with 20 wt% DTA can reach 76.38MPa. DTA released from bone cement up to 14 days accounted for only 2.3% of its dosage. The water contact angle was 62.3°. The contrast of bone cement on X-ray film was comparable to that of bone cement containing 30 wt% barium. The hemolysis rate was lower than 4%, and there was no obvious hemolysis. PMMA with 20 wt% DTA can maintain the relative growth rate of MC3T3-E1 and L929 cells above 80%. The results show that adding 20 wt% DTA into PMMA can obtain good radiopacity while maintaining its mechanical properties, setting properties, and biocompatibility. DTA can be used as a promising candidate material for PMMA bone cement radiopacifier.

Influence of Initiator Concentration on the Polymerization Course of Methacrylate Bone Cement.

Background: The amount of oxidant (initiator) and reductant (co-initiator) and their ratio have a significant effect on the properties of polymethacrylate bone cement, such as maximum temperature (Tmax), setting time (tset) and compressive strength (σ). The increase in the initiating system concentration causes an increase in the number of generated radicals and a faster polymerization rate, which shortens the setting time. The influence of the redox-initiating composition on the course of polymerization (rate of polymerization and degree of double bond conversion) and the mechanical properties of bone cement will be analyzed. Methods: Bone cements were synthesized by mixing a powder phase composed of two commercially available methacrylate copolymers (Evonic) and a liquid phase containing 2-hydroxyethyl methacrylate (HEMA), methyl methacrylate (MMA), and triethylene glycol dimethacrylate (D3). As an initiating system, the benzoyl peroxide (BPO) as an oxidant (initiator) in combination with a reducing agent (co-initiator), N,N-dimethylaniline (DMA), was used. Samples were prepared with various amounts of peroxide BPO (0.05%, 0.1%, 0.2%, 0.3%, 0.5% and 0.7% by weight) with a constant amount of reducing agent DMA (0.5 wt.%), and various amounts of DMA (0.25%, 0.35% and 0.5% by weight) with a constant amount of BPO (0.3 wt.%). The polymerization kinetics were studied by differential scanning calorimetry (DSC). Doughing time and compressive strength tests were carried out according to the requirements of the ISO 5833:2002 standard. Results: The increase in polymerization rate was due to the increase in the amount of BPO. In addition, the curing time was shortened, as well as the time needed to achieve the maximum polymerization rate. The final conversion of the double bonds in the studied compositions was in the range 74-100%, and the highest value of this parameter was obtained by the system with 0.3 wt.% of BPO. The doughing times for each BPO concentration were in the range of 90-140 s. The best mechanical properties were obtained for the cement following the initiating system concentrations: 0.3 wt.% of BPO and 0.5 wt.% of DMA. Nevertheless, all tested cements met the requirements of the ISO 5833:2002 standard. Conclusions: Based on the conducted polymerization kinetic studies, the best reaction conditions are provided by an initiating system containing 0.3 wt.% of BPO oxidant (initiator) and 0.5 wt.% of DMA reductant (co-initiator). A decrease in the DMA amount caused a decrease in the polymerization rate and the amount of heat released during the reaction. The change in BPO and DMA concentrations in the composition had little effect on the doughing time of the studied bone cement. The cements showed similar doughing times, ranging from 90-225 s, which is comparable to the bone cement available on the market.

Prospects for Adding Drugs with Known Anti-tuberculosis Activity to the Composition of Bone Cement for Treatment of Tuberculous Arthritis

The objective: to evaluate the possibility of using linezolid, amikacin, levofloxacin and bedaquiline mixed with bone cement for the treatment of patients with tuberculous arthritis taking into account changes in mechanical properties of bone cement, antimycobacterial activity of drugs and characteristics of their release.Subjects and Methods. The antimycobacterial, elution and strength characteristics of bone cement mixed with the drugs known for their anti-tuberculosis activity were studied: linezolid, amikacin, levofloxacin, and bedaquiline. The antimycobacterial effect was evaluated by the minimum inhibitory concentration (MIC) of the reference strain of Mycobacterium tuberculosis H37RV sensitive to anti-tuberculosis drugs (TB drugs). To study the kinetics of elution, the methods of high-performance mass spectrometry and spectrophotometry were used. The strength characteristics were determined using LFM-50 electromechanical testing machine.Results. The obtained results demonstrated satisfactory elution and antimycobacterial parameters for linezolid and amikacin, thus they can be mixed with bone cement, and the cement retained its strength characteristics. Levofloxacin showed antimycobacterial activity only within 1 day after the cement sample was immersed in the solution. Bedaquiline showed negative elution and antimycobacterial characteristics in the cement sample.

Mechanical Properties of Bone Cement Affected by Porosity

Mechanical Properties of Bone Cement Affected by Porosity

Experimental study of the mechanical properties of Palacos bone cements

Background. Currently, bone cements are widely used in orthopedics. The range of prescriptions for bone cement use is very large, and requires different qualities depending on the purpose. Therefore, researchers are forced to conduct their own invetigations to study the mechanical properties of bone cements. The purpose was to determine in the experiment the value of an elastic modulus and ultimate strength of Palacos bone cements for further use in mathematical models of osteosynthesis and arthroplasty. Materials and methods. Samples of two brands of cement, Palacos R and Palacos fast, were examined. Samples with a diameter of 5 mm and a length of 10 mm were made from each type of cement. The study was carried out 2 hours and 2 days after polymerization. At each stage, 10 cement samples of each type were tested for compression. Results. After 2 hours of polymerization, the Palacos fast samples had a statistically significant advantage in terms of the tensile strength, which was 105.77 ± 3.19 MPa, over the Palacos R — 87.24 ± 3.70 MPa. The higher elastic modulus for Palacos fast samples — 2,942.50 ± 99.67 MPa compared to Palacos R — 82,542.40 ± 65.55 MPa turned out to be statistically significant. Two days after fabrication, the strength characteristics of bone cements changed upward. Thus, the ultimate strength of Palacos fast samples was determined within 116.39 ± 2.85 MPa, which is statistically significant higher than for Palacos R samples for which this indicator was within 95.58 ± 4.53 MPa. Similar tendencies were characteristic of an elastic modulus, which amounted to 3,048.93 ± 108.70 MPa for Palacos fast and 2,642.90 ± 22.93 MPa — for Palacos R samples. The value of the elastic modulus for both brands of bone cement has a statistically significant tendency to increase. On average, an elastic modulus for Palacos R cement increased by 4.0 ± 2.6 %, for Palacos fast samples — by 3.5 ± 1.4 %. Conclusions. Palacos R bone cement by the end of the polymerization process has an elastic modulus of 2,542.40 ± 65.55 MPa and a tensile strength of 87.24 ± 3.70 MPa, which is statistically significant lower (p = 0.001) than thereof Palacos fast cement (2,942.50 ± ± 99.67 MPa and 105.77 ± 3.19 MPa, respectively). The indicators of the tensile strength and elastic modulus of the samples of bone cement of both studied brands have a statistically significant (p = 0.001) tendency to increase within 2 days, on average by 9.6 ± 10.1 % and 3.5 ± 4.0 %, respectively. The obtained elastic modulus and ultimate strength of Palacos R and Palacos fast bone cements can be used for mathematical modeling of various types of arthroplasty.

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.

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.

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.

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.

Influence of Antibiotics Addition in Bone Cements for Hip Arthroplasty on their Mechanical Properties: Clinical Perspective and&lt;i&gt; In Vitro&lt;/i&gt; Tests

Bone cement has been used for over half a century, to successfully anchor artificial joints. From its emergence there have appeared a number of types of bone cement, with the 2 major classes being bone cement with or without active substances. The one with the added antibiotics is used primarily in the treatment and revision surgery of infected total hip arthroplasty (THA), as well as a prophylactic method in primary THA in patients with high risks for this complication. The purpose of this study is to determine the mechanical properties of bone cement with added antibiotics. Over a period of 2 years, a number of 41 cases were chosen for this study: 25 with revision surgery for THA, where bone cement with antibiotics was used, and 16 with primary THA, where regular bone cement was used. A number of studies have been performed on the mechanical properties of the 2 types of cement, which determined that the cement with antibiotics presents a slightly lower compressive strength, tensile strength, elastic modulus and fatigue strength compared with regular cement. These variations, however, become more pronounced as the quantity of the antibiotic goes up. The mechanical properties of the cement with antibiotics are similar with those of the regular cement, when low doses of antibiotics are used and become more evident as the doses go up. In conclusion, the antibiotic bone cement is a trustworthy tool in the surgeon’s arsenal against infection, with minimal detriments from the mechanical view.