Steel Implants Research Articles

Nickel allergy requiring plate removal after implantation of stainless steel and titanium plates after polytrauma

Nickel allergy requiring plate removal after implantation of stainless steel and titanium plates after polytrauma

Failure Analysis of Austenitic Stainless Steel Implant Screws and Prospection of Chemical Composition Using Artificial Intelligence

In this work, austenitic stainless steel screws employed in a locking compression plate for veterinarian use were investigated. These types of implants are widely utilized in bone fractures healing. Two surgical screws were extracted due to the observation of slight superficial red rust colorizing on one of the screw implants, visual evidence of probable screw rusting. From the same implant, another screw was extracted simultaneously without visual evidence of rusting. In order to characterize and analyze the different behavior of both screws, the chemical composition was characterized by atomic absorption and energy dispersive X-ray spectroscopy (EDS) coupled to a scanning electron microscope (SEM). Also, the screws were studied by metallography, optical microscopy (OM), Vickers microhardness tests, and SEM analysis. On the other hand, a prospection for alloy chemical composition limits of these types of implants was performed based on the Schaeffler-Delong diagram and the ASTM F-138 standard. To analyze the effect of the chemical composition, heat treatment, microstructure, pitting resistance equivalent number (PRE) and stacking fault energy (SFE), a genetic algorithm (GA) and an artificial neural network (ANN) were used. In accordance with the elemental analysis, the surgical screws do not fulfill the ranges of the chemical composition established by the ASTM F-138 standard. Furthermore, there were found differences between the microstructures of the screws. In regard to the prospection, the results of GA and ANN support the proposed chemical composition region on the Schaeffler-Delong diagram. The corrosion failure was associated with severe plastic deformation and the presence of precipitates. The proposal can minimize the cause of failures in these types of austenitic stainless steel implants.

Structural and electrochemical corrosion studies of spin coated ZrO2 thin films over stainless steel alloy for bone defect applications.

Sol-Gel-based reaction mixture sols have been long used to fabricate dense and uniform bioactive coatings with superior mechanical stability over metallic implants. On account of precise control over synthesis, fabrication, formed and low temperature of processing, this technology is one of the most feasible routes to produce bio-ceramic coatings. The study aims to develop a physical barrier over metal implants in form of bioinert Zirconia coatings, phase-stabilized using Dysprosium. The metallic substrates were cut into 10 mm × 10 mm samples and diamond polished after being polished with a 1000 grade emery sheet. Novel spin-coated zirconia films were fabricated over 316L Stainless steel substrates and were sintered at 600°C to obtain firm and uniform crack-free coatings. The thickness of the coatings was determined by ELCA-D meter thermal analysis was performed using TGA-DTA. Phase determination was performed using X-Ray diffraction followed by morphological investigations using Scanning electron microscopy. The corrosion resistance was evaluated with Polarization studies and electrokinetic data was derived using Tafel extrapolation. Biocompatibility evaluation was performed against MG-63 cell lines and RBCs along with bone-forming ability in vitro in SBF. Stable crack-free 3 Layer coatings fabricated at 2000 rpm for 3 s with a thickness of around 1 μm were found to be optimal for corrosion resistance behavior of steel implants at a low ICorr value of 0.501 µA/cm2 and adhesion strength of 40.93 MPa when untreated falling down to 39.92 MPa when immersed in SBF. The study concludes that medium rpm coatings sustain enough sol to produce crack-free coatings that form a strong physical barrier between body fluid and implant surface thereby reducing the attack of corrosive ions and protecting the implant surface without participating in any form of bioactivity but supporting native bone regeneration capabilities.

In situ surface modification of stainless steel with hydroxyapatite using microwave heating

The present work involves enhancing the biocompatibility of austenitic stainless steel (SS-316L) implants by changing its surface composition and morphology through the microwave hybrid heating (MHH) technique. The polished SS-316L alloy surface layer was modified with bioactive hydroxyapatite (HAP) powder by utilizing an Industrial microwave oven operated at 2.45 GHz and 1.1 kW. The modified layer of SS-316L alloy was characterized in terms of phase analysis, microstructure investigation, porosity analysis and apatite forming ability. The microstructural investigation revealed that the presence of austenite dendrites with HAP along with some reaction induced phases like Fe3P, FeP, and Fe2P mainly in the inter-dendritic regions of the modified layer of SS-316L alloy. The microhardness of modified layer was higher than that of the unmodified layer of SS-316L alloy. The modified layer exhibited porosity in the range of 2% to 3%. The in-vitro study performed in simulated body fluid (SBF) solution indicates that the microwave-assisted surface modified layer of SS-316L alloy exhibited an improved bioactivity. The SEM images indicate the formation of apatite layer in the modified layer of SS-316L alloy. The observed biological improvements in the microwave-assisted modified layer was due to the cladding induced changes in the surface morphology and surface chemistry of the SS-316L substrate material.

A systematic review of the use of titanium versus stainless steel implants for fracture fixation.

Background:Controversy exists regarding the use of titanium and stainless steel implants in fracture surgery. To our knowledge, no recent, comprehensive review on this topic has been reported.Purpose:To perform a systematic review of the evidence in the current literature comparing differences between titanium and stainless steel implants for fracture fixation.Methods:A systematic review of original research articles was performed through the PubMed database using PRISMA guidelines. Inclusion criteria were English-language studies comparing titanium and stainless steel implants in orthopaedic surgery, and outcome data were extracted.Results:The search returned 938 studies, with 37 studies meeting our criteria. There were 12 clinical research articles performed using human subjects, 11 animal studies, and 14 biomechanical studies. Clinical studies of the distal femur showed the stainless steel cohorts had significantly decreased callus formation and an increased odds radio (OR 6.3, 2.7-15.1; P < .001) of nonunion when compared with the titanium plate cohorts. In the distal radius, 3 clinical trials showed no implant failures in either group, and no difference in incidence of plate removal, or functional outcome. Three clinical studies showed a slightly increased odds ratio of locking screw breakage with stainless steel intramedullary nails compared with titanium intramedullary nails (OR 1.52, CI 1.1-2.13).Conclusion:Stainless steel implants have equal or superior biomechanical properties when compared with titanium implants. However, there is clinical evidence that titanium plates have a lower rate of failure and fewer complications than similar stainless steel implants in some situations. Although our review supports the use of titanium implants in these clinical scenarios, we emphasize that further prospective, comparative clinical studies are required before the conclusions can be made.

Inhibitory effect of L-Threonine and L-Lysine and influence of surfactant on stainless steel corrosion in artificial body solution

Stainless steel 316L is a biomaterial, widely used in medicine for the fabrication of implants in orthopedics and cardiovascular surgery. The human body is an extremely aggressive environment and materials used for implants need to be highly resistant to corrosion and degradation. Corrosion of steel leads to the release of ions which are toxic to humans and may cause inflammatory processes in the body. Therefore, it is very important to decrease corrosion of stainless steel implants and to find inhibitors that will not cause health effects and that can be safely used. Amino acids are biomolecules that have confirmed action as corrosion inhibitors in aggressive solutions. The aim of this study is to investigate the inhibition action of rarely studied amino acids, L-Lysine and L-Threonine, on the corrosion process of stainless steel in artificial body solution using open circuit potential measurements, potentiodynamic measurements, electrochemical impedance spectroscopy measurements, surface scanning by atomic force microscopy (AFM) and quantum chemical calculation during the investigation. In order to increase the inhibition efficiency, sodium dodecyl sulphate (SDS) was used as an agent for modification of stainless steel surface that provides effortless adsorption of L-Lysine molecules on the electrode surface. Results obtained by potentiodynamic polarization measurements reveal that L-Lysine and L-Threonine act like mixed-type inhibitors with a more pronounced influence on cathodic processes. Also, potentiodynamic curves indicate that L-Lysine and L-Threonine act through adsorption onto the steel surface without changing the mechanism of corrosion of steel. Adsorption follows the Langmuir adsorption isotherm. EIS measurements reveal that charge transfer resistance increases in the presence of amino acids and after pretreatment in SDS solution indicating an increase of protection ability of formed film on the stainless steel surface. Results achieved by AFM reveal that the steel surface becomes smoother in BM − 3 solution with the addition of L-Lysine, suggesting adsorption of the amino acid molecule on the electrode surface. AFM results also indicate that SDS facilitates adsorption of amino acid molecules onto the steel surface. DFT results provide theoretical support for the results obtained by electrochemical studies. Taken together, experimental and theoretical results reveal that tested amino acids can be used as corrosion inhibitors in artificial body solution.

Morphological and mechanical characterization of chitosan/gelatin/silica-gentamicin/bioactive glass coatings on orthopaedic metallic implant materials

Metals are the most widely used materials for orthopedics and dentistry due to their high mechanical properties. However, for certain uses like fixation plates and screws, dental implants, and osseo-articular prosthesis, their surface characteristics such as non-toxic and non-corrosive behavior, good cell adhesion and proliferation, and resistance to bacterial biofilm formation should be accompanied with high mechanical performance. One way to improve metallic implant performance in vivo is to coat them with biopolymer or inorganic thin films. This work describes two multifunctional coating systems for orthopedic titanium and stainless steel implants. Titanium implants were coated with a system consisting of a base hybrid sol-gel layer with bioactive glass particles (applied via spraying) and a top chitosan/gelatin layer with silica-gentamicin nanoparticles (applied via electrophoretic deposition, EPD). Stainless steel implants, which are designed to be removable, were coated only with the top chitosan/gelatin/ silica-gentamicin nanoparticles layer with the aim of providing a temporal attachment to bone and to combat possible bacterial adhesion. The microstructural and mechanical characterization of the coatings was conducted by optical microscopy, transmission and scanning electron microscopy, digital image processing, as well as nanoindentation and nanoscratch tests to advance the understanding of their elastic-plastic, morphologic and adhesive behavior. The coatings were homogeneous, providing good coverage to both substrates. Their surface properties, such as roughness and wettability, indicate that they represent excellent substrates for cell attachment. Bioactive glass particles can be added to titanium implant systems as bioactive components without affecting adhesion or mechanical performance of the chitosan/gelatin/silica-gentamicin nanoparticle EPD coatings. The increase in both hardness and elastic modulus of the coated systems could be due to the presence of the silica-gentamicin nanoparticles and their compaction during the penetration of the indenter. When the samples are subjected to scratch tests, the critical load increases with the reinforcement of the coatings by the silica-gentamicin nanoparticles absorbing the applied load and maintaining the elastic properties of the coatings.

A systematic review and meta-analyses on animal models used in bone adhesive research.

Currently, steel implants are used for osteosynthesis of (comminuted) fractures and intra‐articular bone defects. These osteosyntheses can sometimes be complicated procedures and can have several drawbacks including stress shielding of the bone. A bone glue might be a safe and effective alternative to current materials. Despite numerous animal studies on bone adhesives, no such material is clinically applied yet. We have conducted a systematic review to summarize the evidence in experimental animal models used in research on bone adhesive materials for trauma and orthopedic surgery. Additionally, we analysed the efficacy of the different bone adhesives for different experimental designs. A heterogeneity in experimental parameters including animal species, defect types, and control measurements resulted in a wide variety in experimental models. In addition, no standard outcome measurements could be identified. Meta‐analysis on bone regeneration between adhesive treatment and nonadhesive treatment showed a high heterogeneity and no statistically significant overall effect (M: −0.71, 95% confidence interval [CI]: −1.63–0.21, p = 0.13). Besides, currently there is not enough evidence to draw conclusions based on the effectiveness of the individual types of adhesives or experimental models. A positive statistically significant effect was found for the adhesive treatment in comparison with conventional osteosynthesis materials (M: 2.49, 95% CI: 1.20–3.79, p = 0.0002). To enhance progression in bone adhesive research and provide valuable evidence for clinical application, more standard experimental parameters and a higher reporting quality in animal studies are needed. Statement of Clinical Significance: Current materials restoring anatomical alignments of bones have several drawbacks. A (biodegradable) adhesive for fixating bone defects can be a treatment breakthrough. Although numerous bone adhesives have been researched, most seemed to fail at the preclinical stage. An overview in this field is missing. This systematic review highlights the relevant parameters for design of experimental bone adhesive studies. It demonstrates evidence regarding benefit of bone adhesives but also that the quality of reporting and the risk of bias in studies need to be improved. The results will aid in designing better quality animal studies for bone adhesive research with higher translational value.

A Bibliometric Analysis and Visualisation of Research Trends in Toxicity of Steel-implants

Steel is one of the most used metals for implants and toxicity is an important issue associated with steel implants. The bibliometric analysis had been conducted to understand the active authors, organizations, journals, and countries involved in the research domain of “Toxicity of steel-implants”. All published articles related to “Toxicity of steel-implants” from “Scopus”, were analyzed using the VOS viewer to develop analysis tables and visualization maps. This article had set the objective to consolidate the scientific literature regarding “Toxicity of steel-implants” and also to find out the trends related to the same. The most active journals in this research domain were the Journal of Biomedical Materials Research and Bio-materials. The most active country was the United States of America, and the leading organization engaged in the research regarding the toxicity of steel-implants was the Tulane University of United States of America. The most active authors were Sousa J. P and Niinomi M.

A Bibliometric Analysis and Visualisation of Research Trends in Allergy of Steel-implants

Steel is one of the most used metals for implants. The bibliometric analysis had been conducted to understand the active authors, organizations, journals, and countries involved in the research domain of “Allergy of steel-implants”. All published articles related to “Allergy of steel-implants” from “Scopus”, were analyzed using the VOS viewer to develop analysis tables and visualization maps. This article had set the objective to consolidate the scientific literature regarding “Allergy of steel-implants” and also to find out the trends related to the same. The most active journals in this research domain were the Contact Dermatitis, Injury, and Journal of Paediatric Surgery. The most active country was the United States of America. The leading organization engaged in the research regarding allergy of steel-implants were University Hospital in Munich and Ludwig- Maximilian University of Germany. The most active authors who had made valuable contributions related to the allergy of steel implants were Summer B. and Thomas P.&#x0D;

Comparison between Subsequent Irradiation and Co-Irradiation into SIMP Steel

A modern Chinese ferritic/martensitic steel SIMP, is a new perspective nuclear structural material for the spallation target in accelerator driven sub-critical system. In this work, aimed at exploring the radiation resistance properties of this material, we investigate the differences between simultaneous Fe and He ions irradiation and He implantation of SIMP steel pre-irradiated by Fe self-ions. The irradiations were performed at 300 °C. The radiation-induced hardening was evaluated by nano-indentation, while the lattice disorder was investigated by transmission electron microscopy. Clear differences were found in the material microstructure after the two kinds of the ion irradiation performed. Helium cavities were observed in the co-irradiated SIMP steel, but not the case of He implantation with Fe pre-irradiation. In the same time, the size and density of Frank loops were different in the two different irradiation conditions. The reason for the different observed lattice disorders is discussed.

Safety and efficacy of cold atmospheric plasma for the sterilization of a Pasteurella multocida–contaminated subcutaneously implanted foreign body in rabbits

To determine whether a stainless steel implant sterilized with a novel cold atmospheric plasma sterilization (CAPS) device adversely affects local tissues in rabbits and whether CAPS was as effective as steam sterilization with an autoclave to inactivate Pasteurella multocida. 31 healthy New Zealand White rabbits. Steam-autoclaved stainless steel implants inoculated with P multocida underwent a second steam autoclave sterilization (AIA) or CAPS (AICAPS). One AIA implant and 3 AICAPS implants were randomly placed subcutaneously at 4 sites in 21 rabbits (84 implants). These rabbits were monitored daily for 5 days for evidence of systemic illness and local tissue reactions at the implantation sites and then euthanized. Samples were taken from each implant site for bacterial culture and histologic examination. Cultures of samples obtained from all sites were negative for bacterial growth. No significant difference was observed in mean skin thickness or erythema between AIA and AICAPS implant sites on any observed day. Also, individual histologic grades for the epidermis, dermis, subcutis, and muscle and total histologic grade were not significantly different between AIA and AICAPS implant sites. Cold atmospheric plasma sterilization was noninferior to steam sterilization of P multocida-contaminated stainless steel implants in the rabbits in the present study. However, studies of the efficacy of CAPS for inactivation of other important bacteria are needed.

Late spinal infections following posterior spinal fusion in pediatric deformities: treatment using single-stage titanium implant exchange.

Late infection following posterior spinal fusion (PSF) for deformity is a leading cause of revision. The purpose of this study is to evaluate clinical and radiographic outcomes following a single-stage debridement and exchange of spinal implants with titanium in adolescent patients with late-onset infections following PSF METHODS: A retrospective review of prospectively collected data of adolescent patients with spinal deformity, who were surgically treated with PSF was collected. Patients were included for the study if they developed late arising infection (> 1year after index posterior fusion for the deformity) from 2006-2019. Treatment consisted of irrigation, debridement, implant exchange with titanium screws and rods, and antibiotics. Parameters evaluated include radiographic Cobb angles, operative data, and clinical data, all at minimum 2-year follow-up. 31 patients (29 with AIS and 2 with Scheuermann's kyphosis) developed late spinal infections. Mean age was 11.4 ± 2.3years, 84% female, mean time from index surgery was 52.5months. 25 had all stainless steel implants and 6 had cobalt chrome during the index procedure. Positive cultures were obtained in 5 patients (2 Staphylococcus Aureus, 1 Staphylococcus epidermidis, 1 Peptostreptococcus, 1 Pseudomonas aeruginosa) with cultures followed till 7days post-operatively. At 2-years following the exchange, there was no change in coronal and sagittal alignment. Three (9%) patients developed subsequent infection necessitating implant removal. A single-stage procedure consisting of implant removal, irrigation, and debridement, and replacement with all titanium implants is an effective treatment strategy in patients developing late wound infection following PSF with regards to maintenance of curve correction and minimizing recurrent infections.

Dynamics of biochemical markers of the connective tissue metabolism in the blood of rats after insertion of steel implants with diamond-like carbon coating into the femur

Objective: It is known that the regeneration of bone tissue after implantation of any structuresdepends on the coating of their surface. Therefore, the research of the influence of steelimplants with diamond-like carbon coating on regeneration of bone tissue in the dynamics afterimplantation is a topical issue.&#x0D; Material and Methods: The study was conducted on 61 male rats,5 of them were intact animals. There were also 2 groups of rats with 28 animals in each group(the 1st group was the control one where implants were without diamond-like carbon coating,the 2nd group was experimental where the implants were without coating). We determined thecontent of glycoproteins, chondroitin sulfates, alkaline phosphatase, total calcium, oxyprolineand osteocalcin in the blood of rats on the 7th, 14th, 30th and 90th days after implantation.&#x0D; Resultsand Discussion: Group 2 rats had a faster osteointegration compared with the group 1 rats, whichwas manifested by the normalization of biochemical markers of bone metabolism (glycoproteins,chondroitinsulfats, oxyproline and osteocalcin) on the 90th day of an experiment.&#x0D; Conclusion:Using steel implants with diamond-like carbon coatings showed that the content of glycoproteinsand chondroitin sulfates increased only on the 7th day; oxyproline and osteocalcin increasedon the 7th, 14th and 30th days after implantation; on the 90th day the rates of these biochemicalmarkers reached the norm, indicating a high efficiency of osteointegration.&#x0D; Bangladesh Journal of Medical Science Vol.20(1) 2021 p.81-85

Effect of Nitrided and Nitrocarburised Austenite on Pitting and Crevice Corrosion Resistance of 316 LVM Steel Implants

Harmful lesions occur in the body around multielement stabilisers made of AISI 316 LVM (Low Vacuum Melted) steel, caused by products of pitting, fretting or crevice corrosion. Preventing the effect is possible by modifying the surface of the steel implants. Therefore, the goal of the paper is the comparison of the mechanical and physiochemical properties of plates for treating deformations of the anterior chest wall made of AISI 316 LVM steel, subjected to diffusion and sterilisation processes and exposed to Ringer’s solution. The surface of the implants was subjected to electrochemical polishing, chemical passivation and, in order to modify their properties, nitrocarburised and nitrided diffusion layers were created on selected stabilisers under glow discharge conditions with the use of an active screen at a temperature of 420 °C, over 60 min. The conducted studies involved the examination of the microstructure of the formed layers, surface roughness testing, analysis of contact angles and surface free energy, examination of resistance to pitting and crevice corrosion and examination of nanohardness. On the basis of the results of the conducted studies, it was established that the most advantageous set of properties after sterilisation and exposure to Ringer’s solution was displayed by implants with a formed diffusion nitrocarburised layer.

A biomimetic engineered bone platform for advanced testing of prosthetic implants

Existing methods for testing prosthetic implants suffer from critical limitations, creating an urgent need for new strategies that facilitate research and development of implants with enhanced osseointegration potential. Herein, we describe a novel, biomimetic, human bone platform for advanced testing of implants in vitro, and demonstrate the scientific validity and predictive value of this approach using an assortment of complementary evaluation methods. We anchored titanium (Ti) and stainless steel (SS) implants into biomimetic scaffolds, seeded with human induced mesenchymal stem cells, to recapitulate the osseointegration process in vitro. We show distinct patterns of gene expression, matrix deposition, and mineralization in response to the two materials, with Ti implants ultimately resulting in stronger integration strength, as seen in other preclinical and clinical studies. Interestingly, RNAseq analysis reveals that the TGF-beta and the FGF2 pathways are overexpressed in response to Ti implants, while the Wnt, BMP, and IGF pathways are overexpressed in response to SS implants. High-resolution imaging shows significantly increased tissue mineralization and calcium deposition at the tissue-implant interface in response to Ti implants, contributing to a twofold increase in pullout strength compared to SS implants. Our technology creates unprecedented research opportunities towards the design of implants and biomaterials that can be personalized, and exhibit enhanced osseointegration potential, with reduced need for animal testing.

Antibacterial, pro-angiogenic and pro-osteointegrative zein-bioactive glass/copper based coatings for implantable stainless steel aimed at bone healing

Stainless steel implants are suitable candidates for bone replacement due to their cytocompatibility and mechanical resistance, but they suffer from lack of bioactivity and are prone to bacterial infections. Accordingly, to overcome those limitations, in this study we developed by electrophoretic deposition (EPD), an innovative surface coating made of (i) zein, a natural fibroblast-friendly polymer, (ii) bioactive glass, a pro-osteogenic inorganic material and (iii) copper containing bioactive glass, an antibacterial and pro-angiogenic material. FESEM images confirmed that porous, uniform and free of cracks coatings were obtained by EPD; moreover, coatings were resistant to mechanical stress as demonstrated by the tape test, resulting in a 4B classification of adhesion to the substrate. The coatings were cytocompatible as indicated by metabolism evaluation of human fibroblasts, endothelial cells and mature or progenitor osteoblasts cultivated in direct contact with the specimens. They also maintained pro-osteogenic properties towards undifferentiated progenitor cells that expressed osteogenic genes after 15 days of direct cultivation. Copper conferred antibacterial properties as biofilm formation of the joint pathogens Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli was significantly reduced in comparison with copper-free coatings (p < 0.05). Moreover, this anti-infective activity resulted as targeted towards bacteria while the cells viability was preserved when cells and bacteria were cultivated in the same environment by a co-culture assay. Finally, copper ability to recruit blood vessels and to inhibit bacterial infection was confirmed in vivo where the growth of S. aureus biofilm was inhibited and the formation of new (<50 μm diameter spread) blood vessels was observed.

Effect of material and dimensions on the mechanical behavior of a dental implant

Abstract Metallic dental implants such as titanium and stainless steel have an elastic modulus 5-14 times greater than that of compact bone (15 GPa). These stiff implants do not adequately strain the bone, which can result in bone resorption through a phenomenon referred to as stress shielding. The implant length and diameter has a significant influence on the stress distribution within the surrounding jawbone. Therefore, the objective of this investigation is to optimize the material and the dimensions of a dental implant. A numerical solution of a 3D finite element analysis using ANSYS software was conducted to achieve this purpose. It was concluded that by using stainless steel, titanium or gold dental implants with a large diameter and short length the values of the maximum von Mises stress values in cortical bone were increased. The maximum increase in von Mises stress can be obtained by using a stainless steel implant. This dental implant will reduce the stress shielding effect as well as yield suitable values with respect to von Mises stress for both porcelain crowns and dental implants, thus increasing the service life of the implant.

Sol-gel coatings incorporating borosilicate bioactive glass enhance anti corrosive and surface performance of stainless steel implants

Abstract Metals are the most used materials as orthopaedic or dental implants due to their excellent mechanical properties. Stainless steel is one of the most commonly used materials based on its excellent mechanical properties and low costs compared with other metals, e.g. titanium alloys. In developing countries it is still one of the most used materials for temporary devices like bone plates and fixation screws and for permanent orthopaedic implants. However, stainless steel does not have good anticorrosive and bioactive surface properties in physiological media in comparison to other metals: stainless steel is not able to create a natural bonding with bone and might release corrosion products that could finally end in the removal of the implant. A promising approach to avoid those effects is to protect the implant with a functional coating, which additionally may have antibacterial properties. In this work, three kinds of bioactive glass particles (silicate, borosilicate and copper-doped borosilicate) were added as a second phase to a hybrid organic-inorganic silica based sol-gel made coating, with the aim of improving the surface properties of stainless steel as implant material. Chemical composition of the particles and coatings as well as the bioactive and anti-corrosive behaviour of the generated coating systems were analysed by Fourier Transformed Infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and by electrochemical tests. After 14 days of immersion in simulated body fluid solution, the particles contained in the coatings presented a slow dissolution, generating phosphate-rich deposits (first insight of bioactivity) and enhancing the electrochemical response.

A systematic review of metal ion concentrations following instrumented spinal fusion.

Metallic spinal implants undergo wear and corrosion which liberates ionic or particulate metal debris. The purpose of this study was to identify and review studies that report the concentration of metal ions following multi-level spinal fusion and to evaluate the impact on clinical outcomes. Databases (PubMed, EBSCO MEDLINE) were searched up to August 2019 for studies in English-language assessing metal ion levels [chromium (Cr), titanium (Ti), nickel (Ni)] in whole blood, serum, or plasma after spinal fusion using a specific search string. Study, patient, and implant characteristics, method of analysis, metal ion concentration, as well as clinical and radiographic results was extracted. The systematic search yielded 18 studies encompassing 653 patients. 9 studies reported Ti ions, eight reported Cr, and six reported Ni. Ti levels were elevated compared to controls/reference range/preoperative baseline in seven studies with the other two reporting no difference. Cr levels were elevated compared to controls/reference range in seven studies with one reporting no difference. Ni levels showed no difference from controls/reference range in four studies with one reporting above normal and another elevated compared to controls. Radiographic evidence of corrosion, implant failure, pseudarthrosis, revision surgery and adverse reaction reporting was highly variable. Metal ions are elevated after instrumented spinal fusion; notably Cr levels from stainless steel implants and Ti from titanium implants. The association between clinical and radiographic outcomes remain uncertain but is concerning. Further research with standardized reporting over longer follow-up periods is indicated to evaluate the clinical impact and minimizing risk.