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The use of magnesium (Mg) and its alloys as potential materials for bone implants is gaining attention of researchers. This is due to their biocompatibility, mechanical properties, and ability to degrade in the body. Plasma Electrolytic Oxidation (PEO) is a promising surface modification technique for enhancing the performance of magnesium and its alloys in orthopedic and dental implants. It helps develop an oxide ceramic layer on the surface. This article provides an in-depth analysis of the recent advancements in PEO of magnesium and related alloys for use in bone implants. It begins by explaining the fundamental principles of PEO, including the electrochemical and plasma processes involved in forming ceramic coatings on magnesium substrates. It then describes how various factors affect the oxide layers. These include the electrolyte mixture, voltage, current density, and treatment length. It focuses on the microstructure, biocompatibility, and corrosion resistance of PEO-treated magnesium alloys. Additionally, it explains the biocompatibility and bioactivity performance of the PEO-coated magnesium alloys. This involves their interactions with biological systems, cell adhesion, proliferation, and osseointegration. The review also covers challenges and limitations of PEO. Its comprehensive analysis of PEO technique, surface characteristics, mechanical properties, corrosion behavior, and biocompatibility aspects is valuable. It's a resource for researchers, clinicians, and materials scientists creating novel, biocompatible magnesium-based materials. These materials are suitable for dental and orthopedic implants. As the field continues to evolve, further research directions and potential breakthroughs are outlined to propel the application of PEO-treated magnesium alloys in the realm of bone implants, offering patients improved medical outcomes and enhanced quality of life. [ABSTRACT FROM AUTHOR]

Manufacturing technology has been refined and described for the fabrication of honeycomb-based bioresorbable networks for temporal bone replacement applications. Two novel techniques, digital light processing and investment casting, were utilized to produce customized, shape-optimized cellular constructs with additional orifices promoting tissue ingrowth during osteo-regeneration. For this purpose, a conventional magnesium casting alloy (AZ91) was chosen. Numerical simulations were conducted to predict the compressive behavior of the proposed biodegradable lightweight scaffolds. Spatial castings were adjusted to possess mechanical properties comparable to the ones of cortical or trabecular bones. Two kinds of protective coatings (plasma electrolytic oxidation and organic ones based on natural polyphenols from tea extract) were deposited and characterized. They can be utilized to control the degradation rate during exploitation to achieve a predictable implant lifespan. The elaborated layers aim to mitigate the rapid corrosion of magnesium substrates by prolonging their bioresorption time and thus expanding their applicability in osseointegration. To evaluate this assumption, immersion tests in phosphate-buffered saline were performed, showing better chemical resistance of PEO coating and as-cast sample (for both mass gain by below 1%), and visible increase in mass of sample coated with organic coating (increase by almost 5%). Compressive strength results from numerical approach were further validated by experimental compression tests, showing that PEO coating deteriorated compressive strength by almost 3%, and organic coating improved it by over 9%. Results achieved in numerical approach were better than expected for stiffer sample, and slightly lower for the one with bigger pores. [ABSTRACT FROM AUTHOR]

Millions of people suffer from bone loss and diseases each year, which give rise to bone-related medical treatments. Multi-material coatings composed of Silicon Substituted Hydroxyapatite (Si-HA) and Silver Substituted Hydroxyapatite (Ag-HA) potentiated its usage as an ideal bone implant material with favourable biological response and antibacterial properties, respectively. Each patient has different conditions (e.g. bone ages, bone density, position, and infection status) and specific bone implant requirement, thus requiring specific designs of Si-HA and Ag-HA bone implant material ratios. In this paper, a recommender system which took advantage of Wide&Deep recommendation architecture and DenseNet architecture was provided and a semi-supervised training process was utilized to recommend appropriate bone implant material ratio (Si-HA:Ag-HA) for each patient to improve the bone disease treatment and recovery. The proposed recommendation system could achieve high accuracy ( 92.2 % ) and efficiency (using only 10 % of labeled data) on test dataset, which could be potentially utilized in future clinical usages and provide doctors with decision support to make better clinical decisions. [ABSTRACT FROM AUTHOR]

Purpose: To quantify union rate, complication rate, reintervention rate, as well as functional outcome after vascularized fibular bone grafts (VFGs) for the treatment of long-bone defects. Methods: A comprehensive search was performed in the PubMed, Web of Science, and Cochrane databases up to August 18, 2020. Randomized controlled trials, comparative studies, and case series describing the various techniques available involving VFGs for the reconstruction of segmental long-bone defects were included. A meta-analysis was performed on union results, complications, and reinterventions. Assessment of risk of bias and quality of evidence was performed with the Downs and Black's "Checklist for Measuring Quality". Results: After full-text assessment, 110 articles on 2226 patients were included. Among the retrieved studies, 4 were classified as poor, 83 as fair, and 23 as good. Overall, good functional results were documented and a union rate of 80.1% (CI 74.1–86.2%) was found, with a 39.4% (CI 34.4–44.4%) complication rate, the most common being fractures, non-unions and delayed unions, infections, and thrombosis. Donor site morbidity represented 10.7% of the total complications. A 24.6% reintervention rate was documented (CI 21.0–28.1%), and 2.8% of the patients underwent amputation. Conclusions: This systematic review and meta-analysis documented good long-term outcomes both in the upper and lower limb. However, VFG is a complex and demanding technique; this complexity means an average high number of complications, especially fractures, non-unions, and vascular problems. Both potential and limitations of VFG should be considered when choosing the most suitable approach for the treatment of long-bone defects. [ABSTRACT FROM AUTHOR]

The issues of designing bone implants capable of creating an electrical stimulus for bone tissue regeneration under the influence of an external magnetic field are considered. A promising method for generating local electric fields is the use of magnetoelectric (multiferroid) micro- and nanoparticles that are polarized under the action of an external magnetic field and create electric fields comparable in amplitude to endogenous ones. Of practical interest are composite magnetoelectric particles consisting of a ferrimagnetic core and a piezoelectric shell brought into close mechanical contact. Modeling the magnetoelectric effect in a composite particle is carried out; composite particles with cobalt ferrite as a magnetostrictor are fabricated, and the issues of the chemical interaction of phases are discussed. [ABSTRACT FROM AUTHOR]

Similar to metallic implant, using the compact bio-nanocomposite can provide a suitable strength due to its high stiffness and providing sufficient adhesion between bone and orthopedic implant. Therefore, using zirconia-reinforced calcium phosphate composites with new generation of calcium silicate composites was considered in this study. Additionally, investigation of microstructure, apatite formation, and mechanical characteristic of synthetic compact bio-nanocomposite bones was performed. Desired biodegradation, optimal bioactivity, and dissolution of tricalcium phosphate (TCP) were controlled to optimize its mechanical properties. The purpose of this study was to prepare the nanostructured TCP-wollastonite-zirconia (TCP-WS-Zr) using the space holder (SH) technique. The X-ray diffraction technique (XRD) was used to confirm the existence of favorable phases in the composite's structure. Additionally, the effects of calcination temperature on the fuzzy composition, grain size, powder crystallinity, and final coatings were investigated. Furthermore, the Fourier-transform infrared spectroscopy (FTIR) was used for fundamental analysis of the resulting powder. In order to examine the shape and size of powder's particles, particle size analysis was performed. The morphology and microstructure of the sample's surface was studied by scanning electron microscopy (SEM), and to evaluate the dissolution rate, adaptive properties, and the comparison with the properties of single-phase TCP, the samples were immersed in physiological saline solution (0.9% sodium chloride) for 21 days. The results of in vivo evaluation illustrated an increase in the concentration of calcium ion release and proper osseointegration ratio, and the amount of calcium ion release in composite coatings was lower than that in TCP single phase. Nanostructured TCP-WS-Zr coatings reduced the duration of implant fixation next to the hardened tissue, and increased the bone regeneration due to its structure and dimensions of the nanometric phases of the forming phases. Finally, the animal evaluation shows that the novel bio-nanocomposite has increasing trend in healing of defected bone after 1 month. [ABSTRACT FROM AUTHOR]

Calcium phosphate (CaP) is well known as biocompatible and bioactive materials that helps in bone growth. However, the brittleness of CaP makes it limited in load-bearing application. The effect of magnesium (Mg) doping in various weight percentages on the physical and mechanical properties of CaP/sodium alginate (SA) biocomposite was investigated. Mg-doped CaP/SA biocomposite powder was prepared by using precipitation method. 95/5 ratio of CaP/SA was used to be doped with different weight percentages (wt%) of Mg. The maximum hardness was attained at 5.34 GPa for 1.5 wt% of Mg-doped CaP/SA. The maximum grain size of 3.75 μm at 1.0 wt% of Mg-doped CaP/SA was observed under scanning electron microscope (SEM) micrograph which also represents the maximum density of 2.91 g/cm3. Characterization of Mg-doped CaP/SA powder through Fourier-transform infrared (FTIR) exhibited the phosphate (PO4) group was reduced with the increase of Mg doping which was also supported in X-ray diffraction (XRD) analysis. From the analyses, Mg ion doping improves the properties of CaP/SA biocomposite. [ABSTRACT FROM AUTHOR]

The mechanical characteristics are studied for macroporous composite implants on the basis of β‑Ca/PO4)2/polylactide and β-Ca/PO4)2/polycaprolactone obtained by means of thermal-extrusion 3D printing. The effect of the degree of filling exerted on the strength, Young's modulus, and the characteristics of the material destruction is described for the polymer, as well as for the three-dimensional structure filled with phosphate cement. [ABSTRACT FROM AUTHOR]

This article addresses the influence of macro-scale channels with a diameter of 1 mm on the physical and mechanical properties of additive-manufactured porous titanium (Ti) structures, which can be used as bone implants. Different orientations and numbers of channels within the additive-manufactured structures were used in this study. The produced samples were characterized through porosity, shrinkage measurements, as well as mechanical compression tests. The results demonstrate that the channel orientation in the structure influences the shrinkage rate in the parts made with horizontally or vertically orientated channels, in which a relatively isotropic shrinkage is achieved after sintering. In addition, mechanical ultimate strength of the structure can be tailored to the desired properties (such as the surrounding bone) via the channel orientation in the structure, where the overall porosity is affected by the number of channels existing in the structure. [ABSTRACT FROM AUTHOR]

Recently, porous Ti-Nb-based shape memory alloys have been considered as promising implants for biomedical application, because of their non-toxic elements, low elastic modulus, and stable superelasticity. However, the inverse relationship between pore characteristics and superelasticity of porous SMAs will strongly affect their clinical application. Until now, there have been few works specifically focusing on the effect of pore structure on the mechanical properties and superelasticity of porous Ti-Nb-based SMAs. In this study, the pore structure, including porosity and pore size, of porous Ti-22Nb-6Zr alloys was successfully regulated by adjusting the amount and size of space-holder particles. XRD and SEM investigation showed that all these porous alloys had homogeneous composition. Compression tests indicated that porosity played an important role in the mechanical properties and superelasticity of these porous alloys. Those alloys with porosity in the range of 38.5%-49.7% exhibited mechanical properties approaching to cortical bones, with elastic modulus, compressive strength, and recoverable strain in the range of 7.2-11.4 GPa, 188-422 MPa, and 2.4%-2.6%, respectively. Under the same porosity, the alloys with larger pores exhibited lower elastic modulus, while the alloys with smaller pores presented higher compressive strength. [ABSTRACT FROM AUTHOR]

In this study, three dimensional printing (3DP) coupled with heat treatment was investigated as a new technique for fabrication of bone implant. An influence of using different content of polyethylene (0.60-0.80 w/w) in the raw material formulation upon the microstructure, density, porosity, shrinkage and tensile properties of porous high density polyethylene structure was investigated. It was found that the relationship between structure and properties was strongly influenced by the interplay between polyethylene content and heat treatment steps. This heat treatment process could increase the properties of porous high density polyethylene significantly over the as-fabricated 3DP sample without destroying porous structure. Porous high density polyethylene bodies having a porosity ranging from 22.3-49.7% and pore diameters of 132.6-136.2 microns with tensile strength up to approximately 4 MPa which was comparable to commercial product could be successfully prepared in this study. Biocompatibility of selected formulation (0.70 w/w) indicated that the prepared structure was not toxic and could support the osteoblast cell proliferation. [ABSTRACT FROM AUTHOR]

Porous NiTi was produced by sintering pre-alloyed NiTi powders (with small Ni addition to form Ni-rich composition) with NaCl powders which are removed to create 40-60 vol.% macropores which are open to the surface, blocky in shape, and 100-400 μm in size. The microporosity present between the NiTi powders is infiltrated by an in situ created NiTi-Nb eutectic liquid which, after solidification, densifies the NiTi powders into dense struts. This processing technique allows for separate control of the macroporous structure, and the densification and composition of the NiTi struts. [ABSTRACT FROM AUTHOR]

In order to investigate the in vivo behavior of pure magnesium and AZ31B and the influence of mineralization induction ability, sample rods were implanted intramedullary into the femora of rabbits. After one and nine weeks, six animals from each group were sacrificed, respectively. Undecalcified cross-sections of implant were performed to observe bone-implant by scanning electron microscopy (SEM) and energy dispersive spectromicroscopy (EDS). The SEM/EDS evaluation showed that there is a thin layer of bone around magnesium and its alloy after nine-week implantation. The results further showed that the aluminum-zinc containing magnesium alloys AZ31B provided a slower degradation rate in vivo than the pure magnesium. At the locations where magnesium was resorbed, the deposition of new bone was found. The results indicate that magnesium is biocompatible, osteo-conductive and is a potential material for use as a degradable bone implant. [ABSTRACT FROM AUTHOR]

A 76-year-old patient suffering from two painful osteolytic metastases in C1 and C4 underwent percutaneous vertebroplasty by a hybrid technique in a multi-functional image-guided therapy suite (MIGTS). Two trocars were first placed into the respective bodies of C1 and C4 under fluoroscopic computed tomography guidance using a lateral approach. Thereafter, the patient was transferred on a moving table to the digital subtraction angiography unit in the same room for implant injection. Good pain relief was achieved by this minimally invasive procedure without complications. A hybrid approach for vertebroplasty in a MIGTS appears to be safe and feasible and might be indicated in selected cases for difficult accessible lesions. [ABSTRACT FROM AUTHOR]

The feasibility of anterior lumbar intervertebral fusion with artificial bone in place of autogenous bone was investigated. Porous hydroxyapatite (HA)/ZrO2 ceramics loading bone morphogenetic protein (BMP) were implanted after removal of lumbar vertebral disc in rabbits. The adjacent intervertebral discs were also removed by the same way and autogenous illic bone was implanted. SEM observation and biomechanical test were carried out. Compound bone had a bit lower osteoinductive activity than autogenous bone by SEM (Osteoindutive activity of artificial bone in 12 weeks was the same as that of autogenous bone in 9 weeks). Biomechanical test revealed that compound bone had lower anti-pull strength than autogeneous bone ( P<0.001), but there was no significant difference in anti-pull strength between compound bone at 12th week and autogenous bone at 9th week (P>0.05). It was concluded that compound bone could, be applied for anterior spinal fusion, especially for those patients who can’t use autogenous bone. [ABSTRACT FROM AUTHOR]