Copper and silver ion implantation of aluminium oxide-blasted titanium surfaces: proliferative response of osteoblasts and antibacterial effects. Int J Artif Organs. 2011;34:882-888. [PMID: 22094570 DOI: 10.5301/ijao.5000022]

Electrophoretically deposited titanium and its alloys in biomedical engineering: Recent progress and remaining challenges

Over the past decade, titanium implants have gained popularity as the number of performed implantation operations has significantly increased. There are a number of methods for modifying the surface of biomaterials, which are aimed at extending the life of titanium implants. The developments in this field in recent years have required a comprehensive discussion of all the properties of electrophoretically deposited coatings on titanium and its alloys, taking into account their bioactivity. The development that took place in this field in recent years required a comprehensive discussion of all the properties of coatings electrophoretically deposited on titanium and its alloys, with particular emphasis on their bioactivity. Herein, we attempt to assess the influence of the electrophoretic deposition (EPD) process parameters on these coatings' biological and mechanical properties. Particular attention has been addressed to the in-vitro and in-vivo studies conducted hitherto. We have seen an increased interest in using titanium alloys without the addition of toxic compounds and gaps in the EPD field such as the uncommon endeavors to develop a "Design of experiments" approach as well as the lack of assessment of the surface free energy and detailed topography of electrophoretically deposited coatings. The exact correlation of coating properties with EPD process parameters still seems explicitly not understood, necessitating more future investigations. Ipso facto, the exact mechanism of particle agglomeration and Hamaker's law need to be fathomable.

Characterization and investigation of electrochemical and biological properties of antibacterial silver nanoparticle-deposited TiO2 nanotube array surfaces

The one of main reasons of the premature failure of Ti-based implants is infections. The metal- and metal oxide-based nanoparticles have very high potential on controlling of infections. In this work, the randomly distributed AgNPs-deposited onto well-ordered TiO₂ nanotube surfaces were fabricated on titanium by anodic oxidation (AO) and electrochemical deposition (ED) processes. AgNPs-deposited nanotube surfaces, which is beneficial for bone tissue growth exhibited hydrophilic behaviors. Moreover, the AgNPs-deposited nanotube surfaces, which prevent the leaching of metallic Ti ions from the implant surface, indicated great corrosion resistance under SBF conditions. The electrochemical corrosion resistance of AgNPs-deposited nanotube surfaces was improved up to about 145% compared to bare Gr2 surface. The cell viability of AgNPs-deposited nanotube surfaces was improved. Importantly, the AgNPs-deposited nanotube surfaces exhibited antibacterial activity for Gram-positive and Gram-negative bacteria. Eventually, it can be concluded that the AgNPs-deposited nanotube surfaces possess high stability for long-term usage of implant applications.

A review on in vitro/in vivo response of additively manufactured Ti-6Al-4V alloy

Bone replacement using porous and solid metallic implants, such as Ti-alloy implants, is regarded as one of the most practical therapeutic approaches in biomedical engineering. The bone is a complex tissue with various mechanical properties based on the site of action. Patient-specific Ti-6Al-4V constructs may address the key needs in bone treatment for having customized implants that mimic the complex structure of the natural tissue and diminish the risk of implant failure. This review focuses on the most promising methods of fabricating such patient-specific Ti-6Al-4V implants using additive manufacturing (AM) with a specific emphasis on the popular subcategory, which is powder bed fusion (PBF). Characteristics of the ideal implant to promote optimized tissue-implant interactions, as well as physical, mechanical/chemical treatments and modifications will be discussed. Accordingly, such investigations will be classified into 3B-based approaches (Biofunctionality, Bioactivity, and Biostability), which mainly govern native body response and ultimately the success in implantation.

Plasma-activated interfaces for biomedical engineering

As an important phenomenon to monitor disease development, cell signaling usually takes place at the interface between organisms/cells or between organisms/cells and abiotic materials. Therefore, finding a strategy to build the specific biomedical interfaces will help regulate information transmission and produce better therapeutic results to benefit patients. In the past decades, plasmas containing energetic and active species have been employed to construct various interfaces to meet biomedical demands such as bacteria inactivation, tissue regeneration, cancer therapy, and so on. Based on the potent functions of plasma modified surfaces, this mini-review is aimed to summarize the state-of-art plasma-activated interfaces and provide guidance to researchers to select the proper plasma and processing conditions to design and prepare interfaces with the optimal biological and related functions. After a brief introduction, plasma-activated interfaces are described and categorized according to different criteria including direct plasma-cells interfaces and indirect plasma-material-cells interfaces and recent research activities on the application of plasma-activated interfaces are described. The authors hope that this mini-review will spur interdisciplinary research efforts in this important area and expedite associated clinical applications.

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The Interfaces between organisms/cells and abiotic materials are crucial for cell signaling.

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Plasmas containing energetic and active species are potent tool to construct biomedical interfaces.

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The objective here is to summarize recent plasma-activated interfaces to spur interdisciplinary efforts for clinical applications.

Biological activity and antimicrobial property of Cu/a-C:H nanocomposites and nanolayered coatings on titanium substrates

Infection associated with titanium based implants remains the most serious problem in implant surgery hence it is important to find optimal strategies to prevent infections. In the present study, we investigated the surface properties, antibacterial activity and biocompatibility of nanocomposite coatings based on an amorphous hydrocarbon (a-C:H) film containing copper nanoparticles (CuNPs) deposited on Ti discs via a gas aggregation cluster source. Three different Cu/a-C:H coatings with approximately the same amount of embedded CuNPs with and without barrier a-C:H layer were fabricated. The obtained results revealed that different structures of the produced coatings have significantly different release rates of Cu ions from the coatings into the aqueous media. This subsequently influences the antibacterial efficiency and osteoblast cell viability of the treated coatings. Coatings with the highest number of CuNPs resulted in excellent antibacterial activity exhibiting approximately 4 log reduction of E.coli and S.aureus after 24 h incubation. The cytotoxicity study revealed that after 7 day cell seeding, even the coating with the highest Cu at.% (4 at.%) showed a cell viability of ̴90%. Consequently, the coating, formed with a properly tailored number of CuNPs and a-C:H barrier thickness offer a strong antibacterial effect without any harm to osteoblast cells.

Preliminary investigation of the effect of doping of copper oxide in CaO-SiO2-P2O5-MgO bioactive composition for bone repair applications

A diopside based bioactive system with a nominal composition of xCuO-(45.55-x)CaO-29.44 SiO₂-10.28P₂O₅-14.73 MgO (x=0,1,3 and 5mol%) has been prepared by sol gel technique in the laboratory. X-ray Diffraction, Fourier Transform Infra-Red and Raman Spectroscopy, Field Emission Scanning Electron Microscopy along with Energy Dispersive X-ray Analysis and pH studies have been undertaken on the prepared samples before and after dipping the samples in simulated body fluid. It has been observed that hydroxyapatite layer starts to form with in 24h during immersion in simulated body fluid. Degradation studies have also been employed to check the degradation behavior in Tris-HCl. Dynamic light scattering studies show that particles are mostly agglomerated and have an average size of 356nm. Zeta potential studies have been undertaken to check the surface charge and it has been estimated that samples carry negative charge when dipped in simulated body fluid. Negative surface charge may contribute to attachment and proliferation of osteoblasts. Samples have also shown the antimicrobial properties against the Vibro cholerae and Escherichia coli pathogens. To check the non-toxic nature of the samples, cell cytotoxic and cell culture studies have been undertaken using the MG-63 cell lines. Samples have shown good response with good percentage viability of the cells in the culture media and hence, provides friendly environment to the growth of cells. The particle size, bioactivity, negative values of zeta potential, antimicrobial properties and good cell viability indicate the potential of the synthesized compositions as possible candidates for bone repair applications.

A review of local antibiotic implants and applications to veterinary orthopaedic surgery

In the face of increasing incidence of multidrug resistant implant infections, local antibiotic modalities are receiving increased attention for both infection prophylaxis and treatment. Local antibiotic therapy that achieves very high antibiotic drug concentrations at the site of the implant may represent an avenue for treatment of biofilmforming bacterial pathogens. Randomized controlled trials in human patients have demonstrated an infection risk reduction when antibiotic-impregnated cement is used for infection prophylaxis in implanted joint prostheses, and when a gentamicin-impregnated collagen sponge is used for infection prophylaxis in midline sternotomy. The other modalities discussed have for the most part yet to be evaluated in randomized controlled trials in veterinary or human patients. In general, the in vivo pharmacokinetics and appropriate dosing profiles for local antibiotic modalities have yet to be elucidated. Toxicity is possible, and attention to the dose applied is warranted.

Predicting lower limb periprosthetic joint infections: A review of risk factors and their classification

AIM

To undertook a systematic review to determine factors that increase a patient's risk of developing lower limb periprosthetic joint infections (PJI).

METHODS

This systematic review included full-text studies that reviewed risk factors of developing either a hip or knee PJI following a primary arthroplasty published from January 1998 to November 2016. A variety of keywords were used to identify studies through international databases referencing hip arthroplasty, knee arthroplasty, infection, and risk factors. Studies were only included if they included greater than 20 patients in their study cohort, and there was clear documentation of the statistical parameter used; specifically P-value, hazard ratio, relative risk, or/and odds ratio (OR). Furthermore a quality assessment criteria for the individual studies was undertaken to evaluate the presence of record and reporting bias.

RESULTS

Twenty-seven original studies reviewing risk factors relating to primary total hip and knee arthroplasty infections were included. Four studies (14.8%) reviewed PJI of the hip, 3 (11.21%) of the knee, and 20 (74.1%) reviewed both joints. Nineteen studies (70.4%) were retrospective and 8 (29.6%) prospective. Record bias was identified in the majority of studies (66.7%). The definition of PJI varied amongst the studies but there was a general consensus to define infection by previously validated methods. The most significant risks were the use of preoperative high dose steroids (OR = 21.0, 95%CI: 3.5-127.2, P < 0.001), a BMI above 50 (OR = 18.3, P < 0.001), tobacco use (OR = 12.76, 95%CI: 2.47-66.16, P = 0.017), body mass index below 20 (OR = 6.00, 95%CI: 1.2-30.9, P = 0.033), diabetes (OR = 5.47, 95%CI: 1.77-16.97, P = 0.003), and coronary artery disease (OR = 5.10, 95%CI: 1.3-19.8, P = 0.017).

CONCLUSION

We have highlighted the need for the provider to optimise modifiable risk factors, and develop strategies to limit the impact of non-modifiable factors.

In Vitro Bioactivity Study of RGD-Coated Titanium Alloy Prothesis for Revision Total Hip Arthroplasty

Total hip arthroplasty (THA) is a common procedure for the treatment of end-stage hip joint disease, and the demand for revision THA will double by 2026. Ti6Al4V (Titanium, 6% Aluminum, and 4% Vanadium) is a kind of alloy commonly used to make hip prothesis. To promote the osseointegration between the prothesis and host bone is very important for the revision THA. The peptide Arg-Gly-Asp (RGD) could increase cell attachment and has been used in the vascular tissue engineering. In this study, we combined the RGD with Ti6Al4V alloy using the covalent cross-linking method to fabricate the functional Ti6Al4V alloy (FTA). The distribution of RGD oligopeptide on the FTA was even and homogeneous. The FTA scaffolds could promote mouse osteoblasts adhesion and spreading. Furthermore, the result of RT-qPCR indicated that the FTA scaffolds were more beneficial to osteogenesis, which may be due to the improvement of osteoblast adhesion by the RGD oligopeptide coated on FTA. Overall, the FTA scaffolds developed herein pave the road for designing and building more efficient prothesis for osseointegration between the host bone and prothesis in revision THA.

Antibacterial potency of different deposition methods of silver and copper containing diamond-like carbon coated polyethylene

Background

Antibacterial coatings of medical devices have been introduced as a promising approach to reduce the risk of infection. In this context, diamond-like carbon coated polyethylene (DLC-PE) can be enriched with bactericidal ions and gain antimicrobial potency. So far, influence of different deposition methods and ions on antimicrobial effects of DLC-PE is unclear.

Methods

We quantitatively determined the antimicrobial potency of different PE surfaces treated with direct ion implantation (II) or plasma immersion ion implantation (PIII) and doped with silver (Ag-DLC-PE) or copper (Cu-DLC-PE). Bacterial adhesion and planktonic growth of various strains of S. epidermidis were evaluated by quantification of bacterial growth as well as semiquantitatively by determining the grade of biofilm formation by scanning electron microscopy (SEM). Additionally silver release kinetics of PIII-samples were detected.

Results

(1) A significant (p < 0.05) antimicrobial effect on PE-surface could be found for Ag- and Cu-DLC-PE compared to untreated PE. (2) The antimicrobial effect of Cu was significantly lower compared to Ag (reduction of bacterial growth by 0.8 (Ag) and 0.3 (Cu) logarithmic (log)-levels). (3) PIII as a deposition method was more effective in providing antibacterial potency to PE-surfaces than II alone (reduction of bacterial growth by 2.2 (surface) and 1.1 (surrounding medium) log-levels of PIII compared to 1.2 (surface) and 0.6 (medium) log-levels of II). (4) Biofilm formation was more decreased on PIII-surfaces compared to II-surfaces. (5) A silver-concentration-dependent release was observed on PIII-samples.

Conclusion

The results obtained in this study suggest that PIII as a deposition method and Ag-DLC-PE as a surface have high bactericidal effects.

Osteogenic response and osteoprotective effects in vivo of a nanostructured titanium surface with antibacterial properties

In implantology, as an alternative approach to the use of antibiotics, direct surface modifications of the implant addressed to inhibit bacterial adhesion and to limit bacterial proliferation are a promising tactic. The present study evaluates in an in vivo normal model the osteogenic response and the osteointegration of an anodic spark deposition nanostructured titanium surface doped with gallium (ASD + Ga) in comparison with two other surface treatments of titanium: an anodic spark deposition treatment without gallium (ASD) and an acid etching treatment (CTR). Moreover the study assesses the osteoprotective potential and the antibacterial effect of the previously mentioned surface treatments in an experimentally-induced peri-implantitis model. The obtained data points out a more rapid primary fixation in ASD and ASD + Ga implants, compared with CTR surface. Regarding the antibacterial properties, the ASD + Ga surface shows osteoprotective action on bone peri-implant tissue in vivo as well as an antibacterial effect within the first considered time point.

Antibacterial efficacy of ultrahigh molecular weight polyethylene with silver containing diamond-like surface layers

Antibacterial coating of medical devices is a promising approach to reduce the risk of infection but has not yet been achieved on wear surfaces, e.g. polyethylene (PE). We quantitatively determined the antimicrobial potency of different PE surfaces, which had been conversed to diamond-like carbon (DLC-PE) and doped with silver ions (Ag-DLC-PE). Bacterial adhesion and planktonic growth of various strains of S. epidermidis on Ag-DLC-PE were compared to untreated PE by quantification of colony forming units on the adherent surface and in the growth medium as well as semiquantitatively by determining the grade of biofilm formation by scanning electron microscopy. (1) A significant (p < 0.05) antimicrobial effect could be found for Ag-DLC-PE. (2) The antimicrobial effect was positively correlated with the applied fluences of Ag (fivefold reduced bacterial surface growth and fourfold reduced bacterial concentration in the surrounding medium with fluences of 1 × 10¹⁷ vs. 1 × 10¹⁶ cm⁻² under implantation energy of 10 keV). (3) A low depth of Ag penetration using low ion energies (10 or 20 vs. 100 keV) led to evident antimicrobial effects (fourfold reduced bacterial surface growth and twofold reduced bacterial concentration in the surrounding medium with 10 or 20 keV and 1 × 10¹⁷ cm⁻² vs. no reduction of growth with 100 keV and 1 × 10¹⁷ cm⁻²). (4) Biofilm formation was decreased by Ag-DLC-PE surfaces. The results obtained in this study suggest that PE-surfaces can be equipped with antibacterial effects and may provide a promising platform to finally add antibacterial coatings on wear surfaces of joint prostheses.

Antimicrobial and osteogenic properties of silver-ion-implanted stainless steel

Prevention of implant loosening and infection is crucial to orthopedic and dental surgeries. In this work, the surface of stainless steel (SS) was modified by silver-sourced plasma immersion ion implantation (Ag-PIII). Metallic silver nanoparticles with various diameters and distributions were fabricated on the SS surfaces after treatment with Ag-PIII for 0.5 and 1.5 h, respectively. The osteogenic activity and antimicrobial properties of SS before and after Ag-PIII treatment were evaluated using in vitro and in vivo tests. The results demonstrated that Ag-PIII treatment not only promoted the antibacterial activity of SS but also enhanced the osteogenic differentiation of human bone marrow stromal cells.

New TiAg composite coating for bone prosthesis engineering shows promising microvascular compatibility in the murine dorsal skinfold chamber model

The incorporation of antimicrobial substances like silver into implant surface coatings is one promising concept against primary infections of endoprosthesis, especially for immunocompromised patients as well as against reinfection after revision operations. However, besides good antimicrobial and mechanical properties it is equally important that the implant material does not disturb the local microvascular perfusion of muscle tissue to enable microbial host defense and tissue repair processes. In this study the biocompatibility of a newly developed TiAg-composite coating applied on conventional titanium via physical vapor deposition was analysed. To evaluate the local microvascular and inflammatory response of striated muscle tissue upon implantation of TiAg-coated plates the murine dorsal skinfold chamber model was used. We repetitively examined local capillary and venular perfusion, endothelial integrity as well as leucocyte activation by intravital fluorescence microscopy at 1 h, 24 h as well as 3 and 7 days after implantation. TiAg-implants were well tolerated by the vascular system as indicated by intact functional capillary density and endothelial integrity compared to pure titanium plates and controls without a metal implant. Furthermore, quantification of rolling and adherent leucocytes did not reveal signs of inflammation upon TiAg-implantation.

Electrospun vancomycin-loaded coating on titanium implants for the prevention of implant-associated infections

The objectives of this work were to develop an antibiotic coating on the surface of a titanium plate to determine its antibacterial properties in vitro and in vivo. To prepare vancomycin-coated titanium implants, we adopted the electrospinning nanotechnique. The surface structure of the coating implants was observed using a scanning electron microscope. An elution method and a high-pressure liquid chromatography assay were used to characterize the release behavior of vancomycin from the coating. The antibacterial efficacy and the cytotoxicity of the coated titanium implants on osteoblasts were investigated in vitro. In addition, X-ray, white blood cell count, C-reactive protein, erythrocyte sedimentation rate, and pathological examination were performed to validate its antimicrobial efficacy in vivo. The antibiotic coating released 82.7% (approximately 528.2 μg) of total vancomycin loading in the coating in vitro. The release behavior of vancomycin from nanofiber coatings exhibited a biphasic release pattern with an initial burst on day 1, followed by a slow and controlled release over 28 days. There was no cytotoxicity observed in vitro for the vancomycin-loaded coating. The vancomycin-coated titanium implants were active in treating implant-associated infection in vivo. Thus, vancomycin-coated titanium implants may be a promising approach to prevent and treat implant-associated infections.

Synergistic effects of dual Zn/Ag ion implantation in osteogenic activity and antibacterial ability of titanium

Zinc (Zn) and silver (Ag) are co-implanted into titanium by plasma immersion ion implantation. A Zn containing film with Ag nanoparticles (Ag NPs) possessing a wide size distribution is formed on the surface and the corrosion resistance is improved due to the micro-galvanic couples formed by the implanted Zn and Ag. Not only are the initial adhesion, spreading, proliferation and osteogenic differentiation of rBMSCs observed from the Zn/Ag implanted Ti in vitro, but also bacteria killing is achieved both in vitro and in vivo. Electrochemical polarization and ion release measurements suggest that the excellent osteogenic activity and antibacterial ability of the Zn/Ag co-implanted titanium are related to the synergistic effect resulting from the long-range interactions of the released Zn ions and short-range interactions of the embedded Ag NPs. The Zn/Ag co-implanted titanium offers both excellent osteogenic activity and antibacterial ability and has large potential in orthopedic and dental implants.

The expanding horizon of prosthetic joint infections

Prosthetic joint infection (PJI) is a serious and potentially devastating complication of arthroplasty. Prior arthroplasty, immunosuppression, severe comorbid conditions, and prolonged surgical duration are important risk factors for PJI. More than half of the cases of PJI are caused by Staphylococcus aureus and coagulase-negative staphylococci. The biofilm plays a central role in its pathogenesis. The diagnosis of PJI requires the presence of purulence, sinus tract, evidence of inflammation on histopathology, or positive microbiologic cultures. The use of diagnostic imaging techniques is generally limited but may be helpful in selected cases. The most effective way to prevent PJI is to optimize the health of patients, using antibiotic prophylaxis in a proper and timely fashion. Management of PJI frequently requires removal of all hardware and administration of intravenous antibiotics. This review summarizes and analyzes the results of previous reports of PJI and assesses the prevention and management of this important entity.

From Koch's postulates to biofilm theory. The lesson of Bill Costerton

The clinical diagnoses of implant infections pose insurmountable difficulties for cultural methods because of their frequent failure when bacteria are growing in biofilms. In 1978 Bill Costerton warned that chronic infections in patients with indwelling medical devices were caused by bacteria growing in well-developed glycocalyx-enclosed biofilms and that bacteria within biofilms resist antibiotic therapies and immune host defenses. Costerton's "biofilm theory" opened two lines of scientific endeavor: the study of the biochemistry and genetics of biofilm formation and function; and, on the other side, the search for new methods for medical diagnosis and treatment of biofilm-centered implant infections. This Editorial and the entire 2012 issue "Focus on Implant Infections" are dedicated to the memory of Bill Costerton, recognized worldwide as the Father of Biofilms for his innovation and body of work on infections caused by sessile bacteria. Bill Costerton was a great scientist, heedful both to the biological aspects of biofilms and to the medical challenges of new diagnostic methods and modern therapeutic approaches to implant infections. But, most of all, he was a charming Maestro for the large number of colleagues and students whose enthusiasm for the science he was able to nourish. Bill passed away on May 12th, 2012 and the entire science community mourns the death of a friend and a leader.

In vivo evaluation of copper release and acute local tissue reactions after implantation of copper-coated titanium implants in rats

Copper (Cu) based coatings can reduce infections for titanium (Ti) implants. However, Cu is also cytotoxic. To examine the balance of antibacterial versus adverse tissue effects, this study aimed at evaluating a Cu coating regarding in vivo Cu release and local inflammatory reactions for 72 h. TiAl6V4 plates received either plasma electrolytic oxidation only (Ti), or an additional galvanic Cu deposition (Ti-Cu). No Staphylococcus aureus were found in vitro on Ti-Cu after 24 h. Following simultaneous intramuscular implantation of two Ti and two Ti-Cu plates into nine rats, serum Cu was elevated until 48 h and residual Cu on explanted samples reduced accordingly after 48 h. Total and tissue macrophages around implants increased until 72 h for both series, and were increased for Ti-Cu. As numbers of total and tissue macrophages were comparable, macrophages were probably tissue-derived. MHC-class-II-positive cells increased for Ti-Cu only. T-lymphocytes had considerably lower numbers than macrophages, did not increase or differ between both series, and thus had minor importance. Tissue reactions increased beyond Cu release, indicating effects of either surface-bound Cu or more likely the implants themselves. Altogether, Ti-Cu samples possessed antibacterial effectiveness in vitro, released measurable Cu amounts in vivo and caused a moderately increased local inflammatory response, demonstrating anti-infective potential of Cu coatings.

Anti-infective and osteointegration properties of silicon nitride, poly(ether ether ketone), and titanium implants

Silicon nitride (Si(3)N(4)) is an industrial ceramic used in spinal fusion and maxillofacial reconstruction. Maximizing bone formation and minimizing bacterial infection are desirable attributes in orthopedic implants designed to adhere to living bone. This study has compared these attributes of Si(3)N(4) implants with implants made from two other orthopedic biomaterials, i.e. poly(ether ether ketone) (PEEK) and titanium (Ti). Dense implants made of Si(3)N(4), PEEK, or Ti were surgically implanted into matching rat calvarial defects. Bacterial infection was induced with an injection of 1×10(4)Staphylococcus epidermidis. Control animals received saline only. On 3, 7, and 14days, and 3months post-surgery four rats per time period and material were killed, and calvariae were examined to quantify new bone formation and the presence or absence of bacteria. Quantitative evaluation of osteointegration to adjacent bone was done by measuring the resistance to implant push-out (n=8 rats each for Ti and PEEK, and n=16 rats for Si(3)N(4)). Three months after surgery in the absence of bacterial injection new bone formation around Si(3)N(4) was ∼69%, compared with 24% and 36% for PEEK and Ti, respectively. In the presence of bacteria new bone formation for Si(3)N(4), Ti, and PEEK was 41%, 26%, and 21%, respectively. Live bacteria were identified around PEEK (88%) and Ti (21%) implants, whereas none were present adjacent to Si(3)N(4). Push-out strength testing demonstrated statistically superior bone growth onto Si(3)N(4) compared with Ti and PEEK. Si(3)N(4) bioceramic implants demonstrated superior new bone formation and resistance to bacterial infection compared with Ti and PEEK.

Interactions of Staphylococci with Osteoblasts and Phagocytes in the Pathogenesis of Implant-Associated Osteomyelitis

In spite of great advancements in the field of biomaterials and in surgical techniques, the implant of medical devices is still associated with a high risk of bacterial infection. Implant-associated osteomyelitis is a deep infection of bone around the implant. The continuous inflammatory destruction of bone tissues characterizes this serious bone infectious disease. Staphylococcus aureus and Staphylococcus epidermidis are the most prevalent etiologic agents of implant-associated infections, together with the emerging pathogen Staphylococcus lugdunensis. Various interactions between staphylococci, osteoblasts, and phagocytes occurring in the peri-prosthesis environment play a crucial role in the pathogenesis of implant-associated osteomyelitis. Here we focus on two main events: internalization of staphylococci into osteoblasts, and bacterial interactions with phagocytic cells.

Preparation of gentamicin-loaded electrospun coating on titanium implants and a study of their properties in vitro

PURPOSE

Implant-related infections are disastrous complications in the clinic, and there are no effective therapies. In this preliminary study, gentamicin-loaded coating on titanium implants was prepared using the electrospinning technique, and some properties of the coating titanium implants were studied.

METHODS

We adopted the electrospinning technique to prepare gentamicin-coated titanium implants. The surface structure of the coating implants was observed using scanning electron microscope. An elution study was performed to determine the release behavior of the gentamicin from the coating. The antibacterial efficacy and quantitative analysis of the bacterial adhesion of Staphylococcus aureus were evaluated in vitro, and the cytotoxicity of the coated titanium implants on osteoblasts was investigated in vitro.

RESULTS

The morphology of the gentamicin-coated titanium implants exhibited nanofibers, and the release of gentamicin showed an initial gentamicin burst followed by a slow release. The gentamicin-coated titanium implants had a persistent antibacterial efficacy for 1 week and significantly reduced the adhesion of the Staphylococcus aureus compared with bare titanium implants in vitro. There was no cytotoxicity observed in vitro for the gentamicin-coated implants.

CONCLUSION

The gentamicin-coated titanium implants, which were prepared using an electrospinning technique, present many advantages and may be considered to prevent and treat the implant-related infections.

New Trends in Diagnosis and Control Strategies for Implant Infections

In implant infections, a quick and reliable identification of the etiological agent is crucial to realizing efficacious therapies. Among molecular methods, automated ribotyping has proven to be an accurate and rapid technique. More recently, MALDI-TOF/MS and PCR-electrospray ionization (ESI)/ MS have been applied successfully to microbiological diagnosis. In implant infections, biofilm is still the major problem for bacterial persistence and recalcitrance to antibiotic therapy. Among biofilm-disrupting agents, enzymes promise the greatest therapeutic possibilities. DNase I degrades biofilm extracellular DNA and has been shown to sensitize biofilm to various biocides and anionic detergents, while dispersin B acts on biofilm exopolysaccharide and, combined with antiseptic, gives a broad-spectrum antibiofilm and antimicrobial activity. The novel antimicrobial approach based on photodynamic treatment (PDT) applies, in combination with antibiotics, to the implant or medical devices reachable by optical fibers. Better progress could be gained by the development of infection-resistant biomaterials able to both inhibit bacterial adhesion and promote tissue integration. New knowledge regarding the fibronectin-mediated internalization of Staphylococcus aureus by osteoblasts, and on its role in the pathogenesis of implant-related osteomyelitis, paves the way for the development of vaccines against staphylococcal adhesins, to prevent both adhesion on biomaterials and bacterial invasion of bone cells.