Nanostructured material formulated acrylic bone cements with enhanced drug release

Local antimicrobial delivery systems for prophylaxis and treatment of periprosthetic traumatological infections

Infections associated with implants are the most serious complications in joint replacement surgeries and can jeopardize the functionality of orthopedic implants. Local antimicrobial delivery could enable antibiotics to attain concentrations above the minimum inhibitory concentration (MIC) threshold at the joint replacement site while preventing systemic side effects. Therefore, there is a dire need for the development of improved biomaterial-based delivery systems for local antibiotic administration in prosthetic infections. In this context, this review highlights the latest breakthroughs in the design of biomaterial-based formulations intended for the prophylaxis and treatment of prosthetic infections. Delivery systems for distinct forms of administration (i.e., direct intra-articular administration, loading into bone cements, coating of implant surfaces, or loading into hydrogels) are here comprehensively compiled with a focus on the design of microparticles and nanosystems for local antimicrobial administration and their impact on distinct in vitro and in vivo models of implant infections.

Enhancing orthopedic outcomes: A comparative analysis of gentamicin sulphate and nanosilver in bone cement

Background

Orthopedic surgeries frequently utilize bone cement, which can increase the risk of postoperative infections. Addressing this challenge, this study aims to enhance the mechanical, physical, and handling properties of bone cement by integrating gentamicin sulfate (GS) and nanosilver (nAg). The objective is to evaluate and compare the effects of these additives on properties such as compressive strength, flexural strength, doughing time, working time, setting time, and exothermic temperature. By doing so, the study seeks to identify a safer and more effective alternative to traditional antibiotics in bone cement formulations, thereby improving clinical outcomes in orthopedic procedures.

Methods

This research involved a comparative analysis of modified cements against standard cements, focusing on compressive strength, flexural strength, doughing time, working time, setting time, and exothermic temperature. Various bone cement samples with GS and nAg additives were prepared and tested in accordance with international standards (ISO 5833:2002 and ASTM F451). Statistical analysis, including one-way and two-way ANOVA tests, was used to assess the significance of the results.

Results

nAg-loaded cements exhibit mechanical and physical properties on par with or supe-rior to those of GS-loaded and standard cements. Notably, nAg incorporation leads to significantly lower exothermic temperatures, reducing the risk of thermal bone tissue damage. This finding highlights that nAg-loaded cement is a safer alternative. Alongside unaltered or enhanced strength, nAgs demonstrate promise for orthopedic applications, particularly in primary arthroplasty. Additionally, nAgs reduce doughing time, enhancing the practicality of these methods in surgical settings.

Conclusions

In conclusion, this study underscores the potential advantages of incorporating GSs and nAgs into bone cement. nAg-loaded cement offers improved properties and reduced infection risk, making it a valuable choice for orthopedic procedures. It enhances both mechanical performance and safety, addressing crucial concerns in orthopedic surgery.

Graphene oxide-encapsulated baghdadite nanocomposite improved physical, mechanical, and biological properties of a vancomycin-loaded PMMA bone cement

Polymethyl methacrylate (PMMA) bone cement is commonly used in orthopedic surgeries to fill the bone defects or fix the prostheses. These cements are usually containing amounts of a nonbioactive radiopacifying agent such as barium sulfate and zirconium dioxide, which does not have a good interface compatibility with PMMA, and the clumps formed from these materials can scratch metal counterfaces. In this work, graphene oxide encapsulated baghdadite (GOBgh) nanoparticles were applied as radiopacifying and bioactive agent in a PMMA bone cement containing 2 wt.% of vancomycin (VAN). The addition of 20 wt.% of GOBgh (GOBgh20) nanoparticles to PMMA powder caused a 33.6% increase in compressive strength and a 70.9% increase in elastic modulus compared to the Simplex® P bone cement, and also enhanced the setting properties, radiopacity, antibacterial activity, and the apatite formation in simulated body fluid. In vitro cell assessments confirmed the increase in adhesion and proliferation of MG-63 cells as well as the osteogenic differentiation of human adipose-derived mesenchymal stem cells on the surface of PMMA-GOBgh20 cement. The chorioallantoic membrane assay revealed the excellent angiogenesis activity of nanocomposite cement samples. In vivo experiments on a rat model also demonstrated the mineralization and bone integration of PMMA-GOBgh20 cement within four weeks. Based on the promising results obtained, PMMA-GOBgh20 bone cement is suggested as an optimal sample for use in orthopedic surgeries.

Research advances of nanomaterials for the acceleration of fracture healing

The bone fracture cases have been increasing yearly, accompanied by the increased number of patients experiencing non-union or delayed union after their bone fracture. Although clinical materials facilitate fracture healing (e.g., metallic and composite materials), they cannot fulfill the requirements due to the slow degradation rate, limited osteogenic activity, inadequate osseointegration ability, and suboptimal mechanical properties. Since early 2000, nanomaterials successfully mimic the nanoscale features of bones and offer unique properties, receiving extensive attention. This paper reviews the achievements of nanomaterials in treating bone fracture (e.g., the intrinsic properties of nanomaterials, nanomaterials for bone defect filling, and nanoscale drug delivery systems in treating fracture delayed union). Furthermore, we discuss the perspectives on the challenges and future directions of developing nanomaterials to accelerate fracture healing.

Nanotechnology development in surgical applications: recent trends and developments

This paper gives a detailed analysis of nanotechnology's rising involvement in numerous surgical fields. We investigate the use of nanotechnology in orthopedic surgery, neurosurgery, plastic surgery, surgical oncology, heart surgery, vascular surgery, ophthalmic surgery, thoracic surgery, and minimally invasive surgery. The paper details how nanotechnology helps with arthroplasty, chondrogenesis, tissue regeneration, wound healing, and more. It also discusses the employment of nanomaterials in implant surfaces, bone grafting, and breast implants, among other things. The article also explores various nanotechnology uses, including stem cell-incorporated nano scaffolds, nano-surgery, hemostasis, nerve healing, nanorobots, and diagnostic applications. The ethical and safety implications of using nanotechnology in surgery are also addressed. The future possibilities of nanotechnology are investigated, pointing to a possible route for improved patient outcomes. The essay finishes with a comment on nanotechnology's transformational influence in surgical applications and its promise for future breakthroughs.

Composite Bone Cements with Enhanced Drug Elution

Antibiotic-loaded bone cement (ALBC) has become an indispensable material in orthopedic surgery in recent decades, owing to the possibility of drugs delivery to the surgical site. It is applied for both infection prophylaxis (e.g., in primary joint arthroplasty) and infection treatment (e.g., in periprosthetic infection). However, the introduction of antibiotic to the polymer matrix diminishes the mechanical strength of the latter. Moreover, the majority of the loaded antibiotic remains embedded in polymer and does not participate in drug elution. Incorporation of the various additives to ALBC can help to overcome these issues. In this paper, four different natural micro/nanoscale materials (halloysite, nanocrystalline cellulose, micro- and nanofibrillated cellulose) were tested as additives to commercial Simplex P bone cement preloaded with vancomycin. The influence of all four materials on the polymerization process was comprehensively studied, including the investigation of the maximum temperature of polymerization, setting time, and monomer leaching. The introduction of the natural additives led to a considerable enhancement of drug elution and microhardness in the composite bone cements compared to ALBC. The best combination of the polymerization rate, monomer leaching, antibiotic release, and microhardness was observed for the sample containing nanofibrillated cellulose (NFC).

A simple method to improve the antibiotic elution profiles from polymethylmethacrylate bone cement spacers by using rapid absorbable sutures

OBJECTIVE

Antibiotic-loaded bone cement beads and spacers have been widely used for orthopaedic infection. Poor antibiotic elution is not capable of eradicating microbial pathogens and could lead to treatment failure. The elution profiles differ among different cement formulations. Although Simplex P cement has the least release amount, it is widely used due to its ready availability. Previous methods aiming to improve the elution profiles were not translated well to clinical practice. We sought to address this by using easily available materials to improve the elution profile of antibiotics from PMMA, which allows clinicians to implement the method intraoperatively.

METHODS

Vancomycin was mixed with Simplex P cement. We used Vicryl Rapide sutures to fabricate sustained-release cement beads by repetitively passing the sutures through the beads and/or mixing suture segments into the cement formulation. Vancomycin elution was measured for 49 days. The mechanism of antibiotic release was observed with gross appearance and scanning electron microscopic images. The antimicrobial activities against MRSA were tested using an agar disk diffusion bioassay.

RESULTS

Passing Vicryl Rapide sutures through cement beads significantly improved the elution profiles in the 7-week period. The increased ratios were 9.0% on the first day and 118.0% from the 2nd day to the 49th day. Addition of suture segments did not increase release amount. The Vicryl Rapide sutures completely degraded at the periphery and partially degraded at the center. The antibiotic particles were released around the suture, while antibiotic particles kept densely entrapped in the control group. The antimicrobial activities were stronger in passing suture groups.

CONCLUSION

Passing fast absorbable sutures through PMMA cement is a feasible method to fabricate sustained-release antibiotic bone cement. Intra-cement tunnels can be formed, and the effect can last for at least 7 weeks. It is suitable for a temporary spacer between two stages of a revision surgery.

Antimicrobial PMMA Bone Cement Containing Long Releasing Multi-Walled Carbon Nanotubes

Prosthetic joint infections (PJIs) ensued from total joint replacement (TJR) pose a severe threat to patients that involve poor health outcomes, severe pain, death (in severe cases), and negative influence patients' quality of life. Antibiotic-loaded bone cement (ALBC) is frequently used for the prevention and treatment of PJI. This work aims to study gentamicin release from carbon nanotubes (CNTs) incorporated in polymethyl methacrylate (PMMA) bone cement to prolong release over several weeks to provide prophylaxis from PJIs after surgery. Different CNT concentrations were tested with the presence of gentamicin as a powder or preloaded onto carboxyl functionalized CNTs. The different types of bone cement were tested for drug release, mechanical properties, water uptake, antimicrobial properties, and cytocompatibility with human osteoblast cells (MTT, LDH, alizarin red, and morphology). Results showed prolonged release of gentamicin from CNT-loaded bone cements over several weeks compared to gentamicin-containing bone cement. Additionally, the presence of CNT enhanced the percentage of gentamicin released without adversely affecting the nanocomposite mechanical and antimicrobial properties needed for performance. Cytotoxicity testing showed non-inferior performance of the CNT-containing bone cement to the equivalent powder containing cement. Therefore, the developed nanocomposites may serve as a novel PMMA bone cement to prevent PJIs.

Influence of Antibiotic-Loaded Acrylic Bone Cement Composition on Drug Release Behavior and Mechanism

Periprosthetic joint infection (PJI) is a devastating complication after total joint replacement with considerable morbidity and large economic burdens. Antibiotic-Loaded Bone Cement (ALBC) has been developed as a valuable tool for local administration and is becoming one of the most effective methods for the prevention and treatment of orthopedic infections. Controlling antibiotic release from ALBC is critical to achieve effective infection control, however, the antibiotic elution rates are generally low, and the mechanisms are poorly understood. Thus, the present study aims to investigate the effects of the basic acrylic bone cement components, including liquid/powder (monomer-to-polymer) ratios, radiopacifier, initiator, and doses of antibiotics on the porosity, antibiotic elution rates and mechanical properties of polymethylmethacrylate (PMMA) based ALBC. The obtained results from the in vitro studies suggested that a reduction in the liquid/powder ratio and an increase in the radiopacifier ratio and gentamicin doses led to increased porosity and release of antibiotic, while the initiator ratio exerted no effect on elution rates. In conclusion, we hope that by varying the composition of ALBC, we could considerably enhance the antibiotic elution rates by increasing porosity, while maintaining an adequate mechanical strength of the bone cements. This finding might provide insights into controlling antibiotic release from ALBC to achieve effective infection control after total joint replacement surgery.

Nanotechnology as an Anti-Infection Strategy in Periprosthetic Joint Infections (PJI)

Background: Periprosthetic joint infection (PJI) represents a devastating consequence of total joint arthroplasty (TJA) because of its high morbidity and its high impact on patient quality of life. The lack of standardized preventive and treatment strategies is a major challenge for arthroplasty surgeons. The purpose of this article was to explore the potential and future uses of nanotechnology as a tool for the prevention and treatment of PJI. Methods: Multiple review articles from the PubMed, Scopus and Google Scholar databases were reviewed in order to establish the current efficacy of nanotechnology in PJI preventive or therapeutic scenarios. Results: As a prevention tool, anti-biofilm implants equipped with nanoparticles (silver, silk fibroin, poly nanofibers, nanophase selenium) have shown promising antibacterial functionality. As a therapeutic tool, drug-loaded nanomolecules have been created and a wide variety of carrier materials (chitosan, titanium, calcium phosphate) have shown precise drug targeting and efficient control of drug release. Other nanotechnology-based antibiotic carriers (lipid nanoparticles, silica, clay nanotubes), when added to common bone cements, enhanced prolonged drug delivery, making this technology promising for the creation of antibiotic-added cement joint spacers. Conclusion: Although still in its infancy, nanotechnology has the potential to revolutionize prevention and treatment protocols of PJI. Nevertheless, extensive basic science and clinical research will be needed to investigate the potential toxicities of nanoparticles.

[Research progress of nanomaterials in osteomyelitis treatment]

Objective

To review the related studies on the application of nanomaterials in the treatment of osteomyelitis, and to provide new ideas for the research and clinical treatment of osteomyelitis.

Methods

The literature about the treatment of osteomyelitis with nanomaterials at home and abroad in recent years was reviewed and analyzed.

Results

At present, surgical treatment and antibiotic application are the main treatment options for osteomyelitis. But there are many defects such as antibiotic resistance, residual bone defect, and low effective concentration of local drugs. The application of nanomaterials can make up for the above defects. In recent years, nanomaterials play an important role in the treatment of osteomyelitis by filling bone defects, establishing local drug delivery system, and self-antibacterial properties.

Conclusion

It will provide a new idea and an important research direction for the treatment of osteomyelitis to fully study the related characteristics of nanomaterials and select beneficial materials to make drug delivery system or substitute drugs.

Modified Cyclodextrin Microparticles to Improve PMMA Drug Delivery Without Mechanical Loss

Antibiotic-loaded poly(methyl methacrylate) (PMMA) cement is commonly used as a local delivery system to treat and prevent orthopedic infections associated with arthroplasties in load-bearing applications. However, these delivery systems are inefficient as release rate sharply declines to subinhibitory levels. Prior studies have shown that by adding in drug-filled cyclodextrin (CD) microparticles into PMMA cement, a more consistent release is observed, and antibiotic refilling through simulated implantation can be achieved. However, the mechanical strengths of PMMA is reduced. In order to decrease the mechanical loss, modified CD microparticles (PMMA-CD) are synthesized that contain covalently appended PMMA chains. The compressive strengths, handling characteristics, and refilling ability of PMMA cement with PMMA-CD are evaluated. Specifically, up to a 13.7% increase in compressive strength is observed when unmodified CD is substituted with PMMA-CD in PMMA samples with 10 wt% CD microparticles. Additionally, a 13.3% increase in working time, a 7.5% decrease in maximum polymerization temperature, and up to a 32.1% increase in amount of drug refilled are observed with the addition of 10 wt% CD PMMA-CD into PMMA in comparison to plain PMMA without CD microparticles.

The Role of Chitosan and Graphene Oxide in Bioactive and Antibacterial Properties of Acrylic Bone Cements

Acrylic bone cements (ABC) are widely used in orthopedics for joint fixation, antibiotic release, and bone defect filling, among others. However, most commercially available ABCs exhibit a lack of bioactivity and are susceptible to infection after implantation. These disadvantages generate long-term loosening of the prosthesis, high morbidity, and prolonged and expensive treatments. Due to the great importance of acrylic bone cements in orthopedics, the scientific community has advanced several efforts to develop bioactive ABCs with antibacterial activity through several strategies, including the use of biodegradable materials such as chitosan (CS) and nanostructures such as graphene oxide (GO), with promising results. This paper reviews several studies reporting advantages in bioactivity and antibacterial properties after incorporating CS and GO in bone cements. Detailed information on the possible mechanisms by which these fillers confer bioactive and antibacterial properties to cements, resulting in formulations with great potential for use in orthopedics, are also a focus in the manuscript. To the best of our knowledge, this is the first systematic review that presents the improvement in biological properties with CS and GO addition in cements that we believe will contribute to the biomedical field.

Effect of zoledronic acid and graphene oxide on the physical and in vitro properties of injectable bone substitutes

The aim of this work was to develop injectable bone substitutes (IBS) consisting of zoledronic acid (ZOL) and graphene oxide (GO) for the treatment of osteoporosis and metastasis. The powder phase was consisting of tetra calcium phosphate (TTCP), dicalcium phosphate dihyrate (DCPD) and calcium sulfate dihyrate (CSD), while the liquid phase comprised of methylcellulose (MC), gelatin and sodium citrate dihyrate (SC), ZOL and GO. The structural analysis of IBS samples was performed by Fourier Transform Infrared Spectroscopy (FTIR). Injectability, setting time and mechanical strength were investigated. Additionally, in vitro properties of synthesized IBS were analyzed by means of bioactivity, ZOL release, degradation, pH variation, PO₄^3- ion release and cell studies. Overall, all IBS exhibited excellent injectability results with no phase separation. The setting time of the IBS was prolonged with ZOL incorporation while the prolonging effect decreased with GO incorporation. The mechanical properties decreased with ZOL addition and increased with the incorporation of GO. The maximum compressive strength was found as 25.73 MPa for 1.5GO0ZOL incorporated IBS. In vitro results showed that ZOL and GO loaded IBS also revealed clinically suitable properties with controlled release of ZOL, pH value and PO₄^3- ions. In in vitro cell studies, both the inhibitory effect of ZOL and GO loaded IBS on MCF-7 cells and proliferative effect on osteoblast cells were observed. Moreover, the prepared IBS led to proliferation, differentiation and mineralization of osteoblasts. The results are encouraging and support the conclusion that developed IBS have promising physical and in vitro properties which needs to be further validated by gene expression and in vivo studies.

Acrylic Bone Cements Modified with Graphene Oxide: Mechanical, Physical, and Antibacterial Properties

Bacterial infections are a common complication after total joint replacements (TJRs), the treatment of which is usually based on the application of antibiotic-loaded cements; however, owing to the increase in antibiotic-resistant microorganisms, the possibility of studying new antibacterial agents in acrylic bone cements (ABCs) is open. In this study, the antibacterial effect of formulations of ABCs loaded with graphene oxide (GO) between 0 and 0.5 wt.% was evaluated against Gram-positive bacteria: Bacillus cereus and Staphylococcus aureus, and Gram-negative ones: Salmonella enterica and Escherichia coli. It was found that the effect of GO was dependent on the concentration and type of bacteria: GO loadings ≥0.2 wt.% presented total inhibition of Gram-negative bacteria, while GO loadings ≥0.3 wt.% was necessary to achieve the same effect with Gram-positives bacteria. Additionally, the evaluation of some physical and mechanical properties showed that the presence of GO in cement formulations increased wettability by 17%, reduced maximum temperature during polymerization by 19%, increased setting time by 40%, and increased compressive and flexural mechanical properties by up to 17%, all of which are desirable behaviors in ABCs. The formulation of ABC loading with 0.3 wt.% GO showed great potential for use as a bone cement with antibacterial properties.

Does the Addition of Poly(glycolide-co-lactide) to Teicoplanin-Containing Poly(methyl methacrylate) Beads Change the Elution Characteristics?

BACKGROUND

The objective of our study was to measure and compare the elution characteristics of teicoplanin from poly(methyl methacrylate) PMMA beads with those of poly(glycolide-co-lactide) PGLA-added beads.

METHODS

The study included two groups of PMMA + teicoplanin beads. PMMA was added to teicoplanin in Group 1 and PMMA + PGLA was added to teicoplanin in Group 2. A total of 16 beads of 1 cm³ were created for each group. Samples were added individually to tubes containing 3 ml of phosphate-buffered saline (PBS). Antibiotic elution was measured by measuring absorbance values of 1-ml samples taken at regular intervals using a UV-Vis spectrophotometer and cumulative percentages of drug release were calculated. In addition, the spectra of teicoplanin were identified using a FTIR spectrophotometer in a wavelength range of 400-4000 cm^-1.

RESULTS

Drug elution in the PBS medium was measured and compared for Groups 1 and 2. The cumulative percentage of drug release from the PGLA-added beads (Group 2) was significantly higher (p = 0.01). The molecular structure of teicoplanin was also confirmed using FTIR.

CONCLUSION

The in vitro results showed that the addition of biodegradable PGLA into bone cement functions as a water-soluble porogen which allows for significant increases in the elution of teicoplanin from cement. This increase in elution suggests that the PGLA would allow for further fluid contact and exchange with the previously entrapped drug. These results may have important clinical applications.

Drug Delivery Based on Nanotechnology for Target Bone Disease

Bone diseases are a serious problem in modern human life. With the coming acceleration of global population ageing, this problem will become more and more serious. Due to the specific physiological characteristics and local microenvironment of bone tissue, it is difficult to deliver drugs to the lesion site. Therefore, the traditional orthopedic medicine scheme has the disadvantages of high drug frequency, large dose and relatively strong side effects. How to target deliver drugs to the bone tissue or even target cells is the focus of the development of new drugs. Nano drug delivery system with a targeting group can realize precise delivery of orthopedic drugs and effectively reduce the systemic toxicity. In addition, the application of bone tissue engineering scaffolds and biomedical materials to realize in situ drug delivery also are research hotspot. In this article, we briefly review the application of nanotechnology in targeted therapies for bone diseases.

Incorporation of multi-walled carbon nanotubes to PMMA bone cement improves cytocompatibility and osseointegration

Acrylic bone cement (ABC) has been used as a grouting agent in joint replacement surgery for over 50 years. In particular, ABC is irreplaceable for high-load joint replacement such as total hip joint replacements (THJRs) and total knee joint replacements because of its excellent mechanical properties. However, the bioactivity of ABC needs to be improved. In this study, we attempted to enhance cytocompatibility and osseointegration of polymethyl methacrylate (PMMA) bone cement via the incorporation of multi-walled carbon nanotube (MWCNT) powders. The results of in vitro rat bone marrow mesenchymal stem cells (rBMSCs) culture on the specimens of PMMA containing different levels of MWCNT loading demonstrated that MWCNT addition improved cell adhesion and proliferation. Furthermore, it was shown from both gene and protein expression levels that MWCNT addition promoted the osteogenic differentiation. For the animal model study, PMMA specimens at different levels of MWCNT loading were implanted into a New Zealand rabbit bone defect model. The results showed that new bone formation occurred inside the bone cement and the integration between the bone cement and bone tissue were significantly enhanced with an increase in MWCNT loading level at 12 weeks post-surgery. Moreover, when the loading of MWCNT was only 1 wt%, the bone ingrowth ratio was up to 42.2% at 12 weeks, and a large number of osteoblasts congregated and new bone formed within the bone cement. In conclusion, cytocompatibility and osseointegration of the bone cements can be controlled by adjusting the MWCNT loading. The whole collection of the present results suggests that MWCNT-incorporated PMMA bone cement may have promise for use in certain orthopedic applications.

LbL-assembled gentamicin delivery system for PMMA bone cements to prolong antimicrobial activity

INTRODUCTION

Antibiotic-loaded poly(methyl methacrylate) bone cements (ALBCs) are widely used in total joint replacement (TJR), for local delivery of antibiotics to provide prophylaxis against prosthetic joint infections (PJI). One of the shortcomings of the current generation of ALBCs is that the antibiotic release profile is characterized by a burst over the first few hours followed by a sharp decrease in rate for the following several days (often below minimum inhibitory concentration (MIC)), and, finally, exhaustion (after, typically, ~ 20 d). This profile means that the ALBCs provide only short-term antimicrobial action against bacterial strains involved PJI.

RATIONALE

The purpose of the present study was to develop an improved antibiotic delivery system for an ALBC. This system involved using a layer-by-layer technique to load the antibiotic (gentamicin sulphate) (GEN) on silica nanoparticles, which are then blended with the powder of the cement. Then, the powder was mixed with the liquid of the cement (NP-GEN cement). For controls, two GEN-loaded brands were used (Cemex Genta and Palacos R+G). Gentamicin release and a host of other relevant properties were determined for all the cements studied.

RESULTS

Compared to control cement specimens, improved GEN release, longer antimicrobial activity (against clinically-relevant bacterial strains), and comparable setting time, cytocompatibility, compressive strength (both prior to and after aging in PBS at 37 oC for 30 d), 4-point bend strength and modulus, fracture toughness, and PBS uptake.

CONCLUSIONS

NP-GEN cement may have a role in preventing or treating PJI.

Antibiotic Elution and Mechanical Strength of PMMA Bone Cement Loaded With Borate Bioactive Glass

Introduction: Local delivery of antibiotics using bone cement as the delivery vehicle is an established method of managing implant-associated orthopedic infections. Various fillers have been added to cement to increase antibiotic elution, but they often do so at the expense of strength. This study evaluated the effect of adding a borate bioactive glass, previously shown to promote bone formation, on vancomycin elution from PMMA bone cement.

Methods: Five cement composites were made: three loaded with borate bioactive glass along with 0, 1, and 5 grams of vancomycin and two without any glass but with 1 and 5 grams vancomycin to serve as controls. The specimens were soaked in PBS. Eluate of vancomycin was collected every 24 hours and analyzed by HPLC. Orthopedic-relevant mechanical properties of each composite were tested over time.

Results: The addition of borate bioactive glass provided an increase in vancomycin release at Day 1 and an increase in sustained vancomycin release throughout the treatment period. An 87.6% and 21.1% increase in cumulative vancomycin release was seen for both 1g and 5g loading groups, respectively. Compressive strength of all composites remained above the weight-bearing threshold of 70 MPa throughout the duration of the study with the glass-containing composites showing comparable strength to their respective controls.

Conclusion: The incorporation of borate bioactive glass into commercial PMMA bone cement can significantly increase the elution of vancomycin. The mechanical strength of the cement-glass composites remained above 70 MPa even after soaking for 8 weeks, suggesting their suitability for orthopedic weight-bearing applications.

Highly dispersed lithium doped mesoporous silica nanospheres regulating adhesion, proliferation, morphology, ALP activity and osteogenesis related gene expressions of BMSCs

Lithium (Li) doped mesoporous silica nanospheres (LMSNs) were synthesized by incorporation of 5 wt% Li into mesoporous silica nanospheres (MSNs) using sol-gel method. The results showed that LMSNs with a mean size of approximate 300 nm exhibited uniform and highly dispersed spherical morphology, which was similar to the morphology of MSNs. Moreover, the degradability of MSNs was significantly increased after the incorporation of Li, and LMSNs could release both silicon (Si) and Li ions in a sustained manner. Due to the release of Li ions, LMSNs showed higher stimulatory effects on the attachment and proliferation of bone marrow mesenchymal stem cells (BMSCs) than MSNs. In addition, LMSNs could also enhance the ALP activity of BMSCs as well as improving osteogenesis related genes (OPN, ALP, Runx2 and OCN) expression of BMSCs. In summary, LMSNs have shown the capability of being a carrier of biologically active ions, which exhibit great potential in bone repair/regeneration applications.

Nanotechnology in orthopedics: a clinically oriented review

The utility of nanotechnology in medicine, specifically within the field of orthopedics, is a topic of extensive research. Our review provides a unique comprehensive overview of the current and potential future uses of nanotechnology with respect to orthopedic sub-specialties. Nanotechnology offers an immense assortment of novel applications, most notably the use of nanomaterials as scaffolds to induce a more favorable interaction between orthopedic implants and native bone. Nanotechnology has the capability to revolutionize the diagnostics and treatment of orthopedic surgery, however the long-term health effects of nanomaterials are poorly understood and extensive research is needed regarding clinical safety.

Antibiotic delivery by nanobioceramics

The role of nanotechnology has evinced remarkable interest in the field of drug delivery. Bioceramics are inorganic biomaterials which are frequently used as bone substitutes. They have been explored in drug delivery as carriers for antibiotics, anti-osteoporotic drugs and anticancer drugs. Bioceramic nanoparticles are excellent alternatives to polymers due to their bioactivity, pH and temperature stability, multifunctionality, biocompatibility and tunable biodegradability. The use of bioceramics for local drug delivery in the field of orthopedics offer an efficient, safe mode of drug delivery directly to the surgical site thereby overcoming the limitations of systemic drug delivery. This review focuses on the development and applications of various nanobioceramics employed as drug delivery systems for the treatment of bone infections.

Nano-carrier based drug delivery systems for sustained antimicrobial agent release from orthopaedic cementous material

Total joint replacement (TJR), such as hip and knee replacement, is a popular procedure worldwide. Prosthetic joint infections (PJI) after this procedure have been widely reported, where treatment of such infections is complex with high cost and prolonged hospital stay. In cemented arthroplasties, the use of antibiotic loaded bone cement (ALBC) is a standard practice for the prophylaxis and treatment of PJI. Recently, the development of bacterial resistance by pathogenic microorganisms against most commonly used antibiotics increased the interest in alternative approaches for antimicrobial delivery systems such as nanotechnology. This review summarizes the efforts made to improve the antimicrobial properties of PMMA bone cements using nanotechnology based antibiotic and non-antibiotic delivery systems to overcome drawbacks of ALBC in the prophylaxis and treatment of PJIs after hip and knee replacement.