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Bone substitutes are widely employed for applications in orthopedic surgery for the replacement of injured bone. Among the diverse methods that are used to design 3D bioceramic matrices, Freeze Foaming has gained attention, since it provides the ability to tune the shape of the created structures. One of the major problems related to these constructs is the lack of porosity at the outwards sides (holder) of the scaffold, thus reducing the cellular affinity and creating a rejection of the implant. In this research, we aimed to develop a bone scaffold with enhanced surface properties and improved cellular affinity. The main aim was to alter the biocompatibility characteristics of the 3D bioceramic constructs. We have produced three-dimensional, complex-shaped hollow shell structures, manufactured by Additive Manufacturing processes and as a second step, filled with a ceramic suspension by the Freeze-Foaming process. 3D constructs from HAP-derived TCP and TCP/ZrO2 were synthesized by freezefoaming method and subsequently irradiated with a fs-laser (λ = 800 nm) spanning a range of parameters for achievement of optimal surface processing conditions. The designed scaffolds demonstrated enhanced topographical properties with improved porosity examined by SEM, EDX, and 3D profilometry after laser treatment. Wettability and computer tomography (CT) evaluation was also performed. The results from X-ray diffraction (XRD) and micro-Raman analysis did not show photochemical and surface or volume defects and changes after laser processing of the ceramic samples. Preliminary results from MG-63 osteoblast-like cell tests showed good cell affinity on the processed surfaces and no cytotoxic effect on the cells. [ABSTRACT FROM AUTHOR]

This research aims to optimize piezoelectric implants for orthopedic applications, enhancing energy harvesting efficiency and mechanical integrity. Our objectives include comparing piezoelectric materials (PZT, PVDF, and BaTiO3) and employing advanced theoretical modeling, finite element analysis (FEA), and validation to identify optimal configurations. Methodologically, this study integrates machine learning and AI-driven techniques to refine design parameters and predict performance outcomes. Significant findings have revealed that PZT demonstrated the highest sensitivity (2 V/mm), achieving a maximum power output of 4.10 Watts, surpassing traditional solutions by over 100%. The optimization process ensured uniform stress distribution, reducing mechanical failure risk, with predictive models showing high accuracy (R-squared value of 97.77%). Error analysis indicated minimal discrepancies, with an average error margin of less than 2%. The conclusions highlight the significant potential of optimized piezoelectric implants in developing durable, efficient, and patient-friendly orthopedic solutions, setting a new standard in intelligent medical device innovation and contributing to enhanced patient care and improved clinical outcomes. [ABSTRACT FROM AUTHOR]

Bone substitutes are widely employed for applications in orthopedic surgery for the replacement of injured bone. Among the diverse methods that are used to design 3D bioceramic matrices, Freeze Foaming has gained attention, since it provides the ability to tune the shape of the created structures. One of the major problems related to these constructs is the lack of porosity at the outwards sides (holder) of the scaffold, thus reducing the cellular affinity and creating a rejection of the implant. In this research, we aimed to develop a bone scaffold with enhanced surface properties and improved cellular affinity. The main aim was to alter the biocompatibility characteristics of the 3D bioceramic constructs. We have produced three-dimensional, complex-shaped hollow shell structures, manufactured by Additive Manufacturing processes and as a second step, filled with a ceramic suspension by the Freeze-Foaming process. 3D constructs from HAP-derived TCP and TCP/ZrO2 were synthesized by freeze-foaming method and subsequently irradiated with a fs-laser (λ = 800 nm) spanning a range of parameters for achievement of optimal surface processing conditions. The designed scaffolds demonstrated enhanced topographical properties with improved porosity examined by SEM, EDX, and 3D profilometry after laser treatment. Wettability and computer tomography (CT) evaluation was also performed. The results from X-ray diffraction (XRD) and micro-Raman analysis did not show photochemical and surface or volume defects and changes after laser processing of the ceramic samples. Preliminary results from MG-63 osteoblast-like cell tests showed good cell affinity on the processed surfaces and no cytotoxic effect on the cells.

This research aims to optimize piezoelectric implants for orthopedic applications, enhancing energy harvesting efficiency and mechanical integrity. Our objectives include comparing piezoelectric materials (PZT, PVDF, and BaTiO3) and employing advanced theoretical modeling, finite element analysis (FEA), and validation to identify optimal configurations. Methodologically, this study integrates machine learning and AI-driven techniques to refine design parameters and predict performance outcomes. Significant findings have revealed that PZT demonstrated the highest sensitivity (2 V/mm), achieving a maximum power output of 4.10 Watts, surpassing traditional solutions by over 100%. The optimization process ensured uniform stress distribution, reducing mechanical failure risk, with predictive models showing high accuracy (R-squared value of 97.77%). Error analysis indicated minimal discrepancies, with an average error margin of less than 2%. The conclusions highlight the significant potential of optimized piezoelectric implants in developing durable, efficient, and patient-friendly orthopedic solutions, setting a new standard in intelligent medical device innovation and contributing to enhanced patient care and improved clinical outcomes.

Magnesium (Mg) alloys are well-known in biomedical materials owing to their elastic module near to bone, biocompatibility and biodegradation properties. Nevertheless, poor corrosion resistance hinders their biomedical applications. Besides, it is necessary to endow Mg alloys with bioactive property, which is crucial for temporary bone implants. Here, a self-healing, corrosion resistant and bioactive duplex coating of plasma electrolytic oxidization (PEO)/polydopamine (PDA) is applied on AZ91 substrate using PEO and subsequent electrodeposition process. Moreover, the role of different electrodeposition times (60 s, 120 s) and dopamine concentrations (1 and 1.5 mg/ml) to improve corrosion resistance, bioactivity, biocompatibility and self-healing property and its mechanism are investigated. The results indicate that the PEO coating is efficiently sealed by the PDA, depending on the electrodeposition parameters. Noticeably, electrodeposition for 120 s in dopamine concentration of 1 mg/ml (120T-1C) results in the formation of uniform and crack-free PDA coating. Duplex PEO/PDA coatings reveal high bioactivity compared to PEO coating, owing to electrostatic interaction between PDA top-layer and calcium and phosphate ions as well as high hydrophilicity of coatings. In addition, duplex PEO/PDA coatings also show improved and more stable protective performance than the PEO and bare alloy, depending on the PDA deposition parameters. Noticeably, the corrosion current density of the 120T-1C decreases one orders of magnitude compared to PEO. In addition, the presence of a broad passivation region in the anodic polarization branch shows durable self-healing property via Zipper-like mechanism, demonstrating the duplex coating could preserve promising corrosion resistance. Furthermore, the cytocompatibility of duplex coated samples is also confirmed via interaction with MG63 cells. In summary, the PEO/PDA coating with great corrosion protection, self-healing ability, bioactivity and biocompatibility could be a promising candidate for degradable magnesium-based implants.

The mechanical properties of hydroxyapatite (HA) have been improved by the addition of either (ZrO2) or hardystonite (HT) by many researchers. However, their dual effect on the tribo-mechanical, electrical, and antibacterial properties of HA has not been studied before. In this regard, nanocomposites of different contents of HA, HT, and ZrO2 were synthesized by a high-energy ball mill and subsequent sintering process. Then, the prepared nanocomposites were characterized by different suitable techniques. Also, their electrical, physical, and tribo-mechanical properties were measured. Besides, their antibacterial effect against S. aureus and E. coli was assessed. The findings demonstrated that the gradual increase of HT and ZrO2 content caused a slight increase in the samples' porosity values; namely 4.3, 4.9, 6, 7.2, and 9.8%, having in mind that these values correspond to those of normal human bones. The maximum enhancement in the microhardness, strength, Young's modulus, and longitudinal, bulk, and shear moduli was recorded for the sample with the maximum content of HT and ZrO2. They were 75, 21.56, 24, 36.36, 32.35, and 22.72%. Additionally, all the prepared samples showed an antibacterial effect against S. aureus bacteria, as indicated by the diameter of the inhibition zone (15, 16, 17, 17, and 18 mm). However, the successive increase in ZrO2 contents was responsible for reducing the electrical conductivity of the prepared nanocomposites up to 3.99 × 10‒7 S/m. The prepared samples may be valid for orthopedic purposes based on the results obtained. The simulation analysis using ANSYS showed that the material with the least stress and buckling under load assigned to the nanocomposite has a higher ZrO2 content. [ABSTRACT FROM AUTHOR]

Titanium alloys, particularly Ti6Al4V, are commonly used in biomedical applications. However, the inclusion of aluminum (Al) and vanadium (V) in this alloy can cause cytotoxic effects in the human body, resulting in Alzheimer's disease and cancer. This study compares the performance of biocompatible alloys containing non-toxic elements, such as tin (Sn) and niobium (Nb), which are considered safe for implantation. Two sets of alloys were selected, Ti5Sn and Ti5Sn5Nb, and their properties were compared to Ti6Al4V. First, the alloys were prepared using a power metallurgical technique. Then, their phase analysis, hardness, wear resistance, strength, and corrosion performance in simulated body fluid (SBF) solution were characterized. Optical microscopy was used to study the microstructure, XRD was used to identify phases, and electrochemical testing was conducted to assess the alloys' anodic and cathodic characteristics. Nanoindentation techniques were used to analyze surface characteristics, such as elastic modulus, nano hardness, and wear resistance. The results showed the alloys containing Nb and Sn had lower corrosion rates in SBF solution compared to Al-containing alloys. Moreover, Nb-containing alloys exhibited the highest hardness, 72% higher than Al-containing alloys. The corrosion-resistant properties of the alloys containing Nb and Sn were higher than those without Nb or Sn, suggesting they may be ideal for orthopedic implants in humans. [ABSTRACT FROM AUTHOR]

Magnesium (Mg) alloys are well-known in biomedical materials owing to their elastic module near to bone, biocompatibility and biodegradation properties. Nevertheless, poor corrosion resistance hinders their biomedical applications. Besides, it is necessary to endow Mg alloys with bioactive property, which is crucial for temporary bone implants. Here, a self-healing, corrosion resistant and bioactive duplex coating of plasma electrolytic oxidization (PEO)/polydopamine (PDA) is applied on AZ91 substrate using PEO and subsequent electrodeposition process. Moreover, the role of different electrodeposition times (60 s, 120 s) and dopamine concentrations (1 and 1.5 mg/ml) to improve corrosion resistance, bioactivity, biocompatibility and self-healing property and its mechanism are investigated. The results indicate that the PEO coating is efficiently sealed by the PDA, depending on the electrodeposition parameters. Noticeably, electrodeposition for 120 s in dopamine concentration of 1 mg/ml (120T-1C) results in the formation of uniform and crack-free PDA coating. Duplex PEO/PDA coatings reveal high bioactivity compared to PEO coating, owing to electrostatic interaction between PDA top-layer and calcium and phosphate ions as well as high hydrophilicity of coatings. In addition, duplex PEO/PDA coatings also show improved and more stable protective performance than the PEO and bare alloy, depending on the PDA deposition parameters. Noticeably, the corrosion current density of the 120T-1C decreases one orders of magnitude compared to PEO. In addition, the presence of a broad passivation region in the anodic polarization branch shows durable self-healing property via Zipper-like mechanism, demonstrating the duplex coating could preserve promising corrosion resistance. Furthermore, the cytocompatibility of duplex coated samples is also confirmed via interaction with MG63 cells. In summary, the PEO/PDA coating with great corrosion protection, self-healing ability, bioactivity and biocompatibility could be a promising candidate for degradable magnesium-based implants. [ABSTRACT FROM AUTHOR]

Background: With increasing requirements for medical effects, and huge differences among individuals, traditional surgical instruments are difficult to meet the patients' growing medical demands. 3D printing is increasingly mature, which connects to medical services critically as well. The patient specific surgical guide plate provides the condition for precision medicine in orthopaedics. Methods: In this paper, a systematic review of the orthopedic guide template is presented, where the history of 3D-printing-guided technology, the process of guides, and basic clinical applications of orthopedic guide templates are described. Finally, the limitations of the template and possible future directions are discussed. Results: The technology of 3D printing surgical templates is increasingly mature, standard, and intelligent. With the help of guide templates, the surgeon can easily determine the direction and depth of the screw path, and choose the angle and range of osteotomy, increasing the precision, safety, and reliability of the procedure in various types of surgeries. It simplifies the difficult surgical steps and accelerates the growth of young and mid-career physicians. But some problems such as cost, materials, and equipment limit its development. Conclusions: In different fields of orthopedics, the use of guide templates can significantly improve surgical accuracy, shorten the surgical time, and reduce intraoperative bleeding and radiation. With the development of 3D printing, the guide template will be standardized and simplified from design to production and use. 3D printing guides will be further sublimated in the application of orthopedics and better serve the patients. The translational potential of this paper: Precision, intelligence, and individuation are the future development direction of orthopedics. It is more and more popular as the price of printers falls and materials are developed. In addition, the technology of meta-universe, digital twin, and artificial intelligence have made revolutionary effects on template guides. We aim to summarize recent developments and applications of 3D printing guide templates for engineers and surgeons to develop more accurate and efficient templates.

The austenitic stainless steel type 316L was engineered with a thin multilayer of tantalum with a thickness of 1.504µm, 3.893 µm and 6.083µm and a duration of 15, 30 and 60 minutes, respectively, by the DC Magnetron Sputtering. Electrochemical behaviors of all three samples were investigated by potentiodynamic and electrochemical impedance spectroscopy techniques. Simulated body fluid was used as the corrosive medium for the electrochemical measurement. The highest corrosion resistance was obtained for the sample subjected to 60 minutes of Ta deposited on 316L S.S. according to EIS measurements, and the lowest corrosion rate of 0.0047 mm/year was obtained for the same sample according to the PD measurements. All the measurements were carried out after the determination of open circuit potential (OCP) at 37˚C with 1 ±°C. All the samples were then characterized by scanning electron microscopy (SEM) to observe the morphology of coating after corrosion. The number of corrosion pits observed from the SEM micrograph was much less on the three coated samples compared to the bare sample. X-ray Photoelectron Spectroscopy (XPS) was used to identify the chemical states of coated and bare 316L SS. Ta4f is present as oxidation states in Ta coated stainless steel 316L, whereas Ta4f is the main species examined along with other elements (C1s, N1s, O1s, Cr2p, Fe2p, Ni2p, and Mo3d). It was also observed that there was strong adhesion between substrate and Ta-coating. After the potentiodynamic studies, results show a significant improvement in corrosion resistance attributed to the strong, stable oxide layer formation.

The biodegradable magnesium (Mg) alloys have been acknowledged amongst the top potential biomedical materials for developing different orthopedic devices. Indeed, the processed Mg alloys' surface integrity shows a substantial contribution to the resulting biomedical applications' performance. In this paper, the effect of various influential process parameters of an ultra-precision diamond turning (UPDT), such as rotational frequency of spindle, tool overhanging (TOH), feed rate (FR), and depth-of-cut (DOC) on the chip formation, shearing mechanism, and surface finish of the biodegradable Mg AZ31 alloy have been studied. The resulting chips' analysis of the different processing parameters has been studied to investigate the involved shearing mechanism. Besides, a relationship between the resulting surface topography and the consequences of UPDT-parameters on skewness ( sk ) and kurtosis ( ku ) was studied. The statistical analysis highlighted that the FR and TOH significantly influenced the surface roughness of the Mg AZ31 alloys at a 95% confidence level. Therefore, being statistically dominating, the morphology of the formed chip has also been influenced by FR and TOH's parametric levels. The UPDT-processed Mg-alloy possessed a nano-finished surface that acted as hydrophobic and could prevent the surface from corrosion. In the light of experimental findings, the UPDT-processed Mg-alloy can be used for orthopedic screws and plates applications. [ABSTRACT FROM AUTHOR]

Magnesium (Mg) is the fourth most abundant element in the human body and is important in terms of specific osteogenesis functions. Here, we provide a comprehensive review of the use of magnesium-based biomaterials (MBs) in bone reconstruction. We review the history of MBs and their excellent biocompatibility, biodegradability and osteopromotive properties, highlighting them as candidates for a new generation of biodegradable orthopedic implants. In particular, the results reported in the field-specific literature (280 articles) in recent decades are dissected with respect to the extensive variety of MBs for orthopedic applications, including Mg/Mg alloys, bioglasses, bioceramics, and polymer materials. We also summarize the osteogenic mechanism of MBs, including a detailed section on the physiological process, namely, the enhanced osteogenesis, promotion of osteoblast adhesion and motility, immunomodulation, and enhanced angiogenesis. Moreover, the merits and limitations of current bone grafts and substitutes are compared. The objective of this review is to reveal the strong potential of MBs for their use as agents in bone repair and regeneration and to highlight issues that impede their clinical translation. Finally, the development and challenges of MBs for transplanted orthopedic materials are discussed.

Titanium alloys, particularly Ti6Al4V, are commonly used in biomedical applications. However, the inclusion of aluminum (Al) and vanadium (V) in this alloy can cause cytotoxic effects in the human body, resulting in Alzheimer’s disease and cancer. This study compares the performance of biocompatible alloys containing non-toxic elements, such as tin (Sn) and niobium (Nb), which are considered safe for implantation. Two sets of alloys were selected, Ti5Sn and Ti5Sn5Nb, and their properties were compared to Ti6Al4V. First, the alloys were prepared using a power metallurgical technique. Then, their phase analysis, hardness, wear resistance, strength, and corrosion performance in simulated body fluid (SBF) solution were characterized. Optical microscopy was used to study the microstructure, XRD was used to identify phases, and electrochemical testing was conducted to assess the alloys’ anodic and cathodic characteristics. Nanoindentation techniques were used to analyze surface characteristics, such as elastic modulus, nano hardness, and wear resistance. The results showed the alloys containing Nb and Sn had lower corrosion rates in SBF solution compared to Al-containing alloys. Moreover, Nb-containing alloys exhibited the highest hardness, 72% higher than Al-containing alloys. The corrosion-resistant properties of the alloys containing Nb and Sn were higher than those without Nb or Sn, suggesting they may be ideal for orthopedic implants in humans.

The primary role of bone tissue engineering is to reconcile the damaged bones and facilitate the speedy recovery of the injured bones. However, some of the investigated metallic implants suffer from stress‐shielding, palpability, biocompatibility, etc. Consequently, the biodegradable scaffolds fabricated from polymers have gathered much attention from researchers and thus helped the tissue engineering sector by providing many alternative materials whose functionality is similar to that of natural bones. Herein, we present the fabrication and testing of a novel composite, magnesium (Mg)‐doped hydroxyapatite (HAp) glazed onto polylactic acid (PLA) scaffolds where polyvinyl alcohol (PVA) used as a binder. For the composite formation, Creality Ender‐3 pro High Precision 3D Printer with Shape tool 3D Technology on an FSD machine operated by Catia design software was employed. The composite has been characterized for the crystallinity (XRD), surface functionality (FTIR), morphology (FESEM), biocompatibility (hemolytic and protein absorption), and mechanical properties (stress‐strain and maximum compressive strength). The powder XRD analysis confirmed the semicrystalline nature and intact structure of HAp even after doping with Mg, while FTIR studies for the successful formation of Mg‐HAp/PVA@PLA composite. The FESEM provided analysis indicated for the 3D porous architecture and well‐defined morphology to efficiently transport the nutrients, and the biocompatibility studies are supporting that the composite for blood compatible with the surface being suitable enough for the protein absorption. Finally, the composite's antibacterial activity (against Staphylococcus aureus and Escherichia coli) and the test of mechanical properties supported for the enhanced inhibition of active growth of microorganisms and maximum compressive strength, respectively. Based on the research outcomes of biocompatibility, antibacterial activity, and mechanical resistance, the fabricated Mg‐HAp/PVA@PLA composite suits well as a promising biomaterial platform for orthopedic applications by functioning towards the open reduction internal fixation of bone fractures and internal repairs. [ABSTRACT FROM AUTHOR]

Bioactive glasses are among the most preferred candidate materials for use in orthopedic applications, thanks to their outstanding properties. However, their low toughness and electrical conductivity are the main disadvantages of their biomedical uses. To improve these mentioned drawbacks, 20Na2O–25CaO–5SiO2-xAg2O–(50 − x)B2O3 glasses, x = 0, 2.5, 5, 7.5 and 10 wt.%, were prepared by melt-quenching method. The amorphous structure together with the chemical composition of these glasses was examined by X-ray diffraction (XRD) technique and Fourier-transform infrared (FTIR) spectroscopy. Then, physical, mechanical, optical and dielectric properties of the prepared glasses were measured. The bioactivity of the prepared samples after being dipped in simulated body fluid was evaluated using the XRD technique. The obtained results showed that increasing the Ag2O content was responsible for improving the fracture toughness of the sample to about 83% without dramatic decreases in other mechanical properties indicating that the prepared samples are desirable for load-bearing sites applications. Also, this increase in Ag2O content was responsible for the improvement in electrical conductivity and all optical properties. Moreover, the presence of Ag2O had a positive role in enhancing the bioactivity of the glass samples. Based on these results, it can be concluded that the prepared glass samples are promising for orthopedic applications. [ABSTRACT FROM AUTHOR]

Magnesium (Mg) is the fourth most abundant element in the human body and is important in terms of specific osteogenesis functions. Here, we provide a comprehensive review of the use of magnesium-based biomaterials (MBs) in bone reconstruction. We review the history of MBs and their excellent biocompatibility, biodegradability and osteopromotive properties, highlighting them as candidates for a new generation of biodegradable orthopedic implants. In particular, the results reported in the field-specific literature (280 articles) in recent decades are dissected with respect to the extensive variety of MBs for orthopedic applications, including Mg/Mg alloys, bioglasses, bioceramics, and polymer materials. We also summarize the osteogenic mechanism of MBs, including a detailed section on the physiological process, namely, the enhanced osteogenesis, promotion of osteoblast adhesion and motility, immunomodulation, and enhanced angiogenesis. Moreover, the merits and limitations of current bone grafts and substitutes are compared. The objective of this review is to reveal the strong potential of MBs for their use as agents in bone repair and regeneration and to highlight issues that impede their clinical translation. Finally, the development and challenges of MBs for transplanted orthopedic materials are discussed. [ABSTRACT FROM AUTHOR]

Large bone defects caused by tumors and traumas are difficult clinical problems. For its treatment, autogenous bone transplantation is the “gold standard”. However, there are some shortcomings of this treatment, such as limited supply and extra trauma from bone removal. In recent years, orthopedic implants and bone tissue engineering materials have developed rapidly, adding impetus to the solution of this problem. At present, the main orthopedic implants include medical metal materials, medical polymer materials, bone cement, ceramic materials, artificial bone materials, etc. Among which medical polymer materials have become the research hotspot and achieved outstanding results in recent years, especially the in-depth study of polyether-ether-ketone (PEEK) materials has great promising to solve this medical problem. PEEK materials have the advantages of non-toxicity, high-temperature resistance, corrosion resistance, abrasion resistance, high strength, high toughness, X-ray radiolucency, and excellent sterilization performance. PEEK materials have been successfully applied in clinical practice and have achieved excellent clinical efficacy and wide recognition. This review overviews the research progress of the performance requirements, material development, and material surface modification of PEEK as an orthopedic implant, and discusses prospects for the advance of medical PEEK materials.

Some treatment options available to repair bone defects are the use of autogenous and allogeneic bone grafts. The drawback of the first one is the donor site’s limitation and the need for a second operation on the same patient. In the allograft method, the problems are associated with transmitted diseases and high susceptibility to rejection. As an alternative to biological grafts, polymers can be used in bone repair. Some polymers used in the orthopedic field are poly(methyl methacrylate), poly(ether-ether-ketone), and ultra-high molecular weight polyethylene (UHMWPE). UHMWPE has drawn much attention since it combines low friction coefficient and high wear and impact resistance. However, UHMWPE is a bioinert material, which means that it does not interact with the bone tissue. UHMWPE composites and nanocomposites with hydroxyapatite (HA) are widely studied in the literature to mitigate these issues. HA is the main component of the inorganic phase in the natural bone, and the addition of this bioactive filler to the polymeric matrix aims to mimic bone composition. This brief review discusses some polymers used in orthopedic applications, focusing on the UHMWPE/HA composites as a potential bone substitute. [ABSTRACT FROM AUTHOR]

Metastable β-type Ti alloys with non-toxic addition elements such as Mo, Zr, Sn, Ta and Nb were developed as an alternative to the widely used Ti-6Al-4V alloy for biomedical applications. These alloys possess enhanced biocompatibility and reduced elastic modulus in comparison with Ti-6Al-4V. Moreover, for orthopedic implants, low Young's modulus is required in order to avoid the stress shielding phenomenon. This study analyzes the microstructure and mechanical properties of a new Ti-12Mo-8Nb alloy after hot swaging, annealing at 950 ºC for 1h and water quenching. The alloy was characterized by X-ray diffraction, optical microscopy and transmission electron microscopy. Tensile tests were performed at room temperature. Young's modulus and hardness values were also measured. The structural characterization reveals a metastable β structure containing only a small amount of α and ω phases. Exhibiting a lower Young's modulus than Ti-6Al-4V and other previously studied Ti-Mo-Nb alloys, the Ti-12Mo-8Nb alloy can be a promising alternative for orthopedic application.

The finite element method (FEM) represents a computer simulation method, originally used in civil engineering, which dates back to the early 1940s. Applications of FEM have also been used in numerous medical areas and in orthopedic surgery. Computing technology has improved over the years and as a result, more complex problems, such as those involving the spine, can be analyzed. The spine is a complex anatomical structure that maintains the erect posture and supports considerable loads. Applications of FEM in the spine have contributed to the understanding of bone biomechanics, both in healthy and abnormal conditions, such as scoliosis, fractures (trauma), degenerative disc disease and osteoporosis. However, since FEM is only a digital simulation of the real condition, it will never exactly simulate in vivo results. In particular, when it concerns biomechanics, there are many features that are difficult to represent in a FEM. More FEM studies and spine research are required in order to examine interpersonal spine stiffness, young spine biomechanics and model accuracy. In the future, patient-specific models will be used for better patient evaluations as well as for better pre- and inter-operative planning.

In the present study, an attempt has been made to improve the mechanical properties, biocompatibility and degradation rate of Mg/3Zn matrix composite, by reinforcing with chemically inert and osteoconductive hydroxyapatite (HA). The composites were synthesized through spark plasma sintering for better consolidation. The HA content, in Mg/3Zn matrix, was optimized with an aim of improving mechanical behavior, corrosion resistance and biocompatibility simultaneously. It has been observed that reinforcement with 15 wt.% HA could slow down the corrosion rate by ~ 60% and improve the hardness and compression strength by ~ 42.8 and 18%, respectively. In vitro studies, up to 56 days, unveil the effect of HA reinforcement in corrosion resistance of magnesium-based matrix. Osteoblastic activity has shown better cell proliferation on the composite surfaces, which were reinforced with HA. [ABSTRACT FROM AUTHOR]

This chapter is an introduction to nanocomposite materials and its classifications with emphasis on orthopedic application. It covers different types of matrix nanocomposites including ceramics, metal, polymer and natural-based nanocomposites with the main features and applications in the orthopedic. In addition, it presents structure, composition, and biomechanical features of bone as a natural nanocomposite. Finally, it deliberately presents developing methods for nanocomposites bone grafting. [ABSTRACT FROM AUTHOR]

Semisolid powder molding was used to prepare the medical Mg-6Zn alloy; in order to further improve its degradation adaptability, 0.5 and 1 wt % Mn were added. Then, the effect of the forming temperature (540, 560, 580, and 600 °C) on the in vitro degradation behavior of the prepared Mg-6Zn- x Mn ( x = 0.5, 1 wt %) was analyzed, and the optimized alloy was obtained. Finally, the biocompatibility and in vivo degradation performance of the optimized and Mn-free alloys were evaluated. Importantly, single-photon emission tomographic imaging (SPECT/CT) was first applied to monitor the in vivo degradation process. The results show that the corrosion mechanism of the Mn-free alloy is microgalvanic corrosion control with corrosive pitting. After adding Mn, the in vitro degradation rate decreases by half (0.17 ± 0.01 mm/year) as the forming temperature increases to 600 °C, and Mg-6Zn-1Mn prepared at 600 °C is the optimized alloy. Mn addition improves the corrosion product film protection and discontinuous secondary phases, and thus, the corrosion mechanism is changed to corrosive pitting control. Additionally, semisolid powder molding is an easy method to prepare alloys with low average pore interconnectivity (<10%), which is helpful for slowing down the degradation rate. The Mn-containing alloy has better biocompatibility, with a cytotoxicity of grade 0-1, due to its lower degradation rate. The in vivo corrosion rate of the Mn-free alloy is 0.19 mm/year after 28 days of implantation, which was precisely detected by SPECT/CT in real-time. The long-term in vivo degradation adaptability of Mn-free and Mn-containing alloys was not correctly presented, which may be due to the unreasonable bone defect model causing implant displacement. However, both of these alloys cause no obvious inflammation and show good healing. In summary, semisolid powder molding is a potentially promising technique to prepare medical Mg alloys, and nuclear imaging is an effective in vivo degradation evaluation method.

The microstructure and mechanical properties of two new metastable β Ti alloys were studied and the influence of the degree of deformation by cold rolling after homogenization heat treatment was also investigated. Both Ti-29Nb-2Mo-6Zr and Ti-24Nb-4Mo-3Zr alloys present a β microstructure after solution heat treatment at 1000 °C for 24 h followed by water quenching whereas ulterior cold rolling induces the precipitation of α” martensite. The results indicate that both alloys are promising alternatives to the widely used Ti-6Al-4V. Young's modulus decreases and hardness increases with the degree of deformation. A thickness reduction of 90% maximizes the hardness/Young's modulus ratio and optimizes the required mechanical properties for orthopedic implants. [ABSTRACT FROM AUTHOR]

A nano-featured tantalum coatings with an average thickness of 800 nm and grain size of 50 nm were successfully prepared by Selective Electron Beam Melted (SEBM) Ti6Al4V substrates by DC magnetron sputtering technology. The details of the physicochemical properties, corrosion resistance and in vitro biocompatibility of the coating were systematically investigated. Elastic modulus of the nano tantalum coatings was around 123.8 GPa and the hardness was 8.08 GPa. Compared with uncoated Ti6Al4V matrix, the corrosion potential of the Ta-Ti64 samples was positively shifted and the corrosion current density decreased from 2.07 × 10−7 to 2.85 × 10−8 A·cm−2 (0.1 mV/s). EIS and PDP results show that the coating enhances the humoral corrosion resistance of Ti6Al4V, which can provide active protection for the substrate to prevent the release of toxic ions caused by long-term corrosion. The mouse osteoblast cell line (MC3T3-E1) is applied in this study for biological evaluation. The optical density at 450 nm results showed that the cell proliferation rate of tantalum coated surface was faster than that of Ti6Al4V sheet and pure tantalum sheet. The 5-day cell adhesion density is 1.26 and 1.32 times higher than uncoated Ti6Al4V and pure tantalum respectively. The nano-structured Ta layer significantly improved the initial adhesion of MC3T3-E1 cells and promoted cell proliferation. The corrosion resistance and biocompatibility of Ta coating are not only better than titanium matrix, but also better than pure tantalum. The results prove that tantalum coating is an effective method to modify titanium alloy and holds a great potential value on 3D printed personalized implants application. [Display omitted] • A dense Ta coating with nanostructure characteristics was successfully fabricated on the surface of 3D-printed Ti6Al4V. • Ta coating enhances the corrosion resistance of Ti6Al4V which effectively protects the matrix from body fluid corrosion. • The nanostructured Ta layer can significantly improve the initial adhesion of MC3T3-E1 cells and their proliferation. • The corrosion resistance and surface bioactivity of nano-structured Ta coatings is also better than 3D-printed pure Ta. [ABSTRACT FROM AUTHOR]

Biodegradability, bone-healing rate, and prevention of bacterial infection are critical factors for orthopedic implants. Polylactic acid (PLA) is a good candidate biodegradable material; however, it has insufficient mechanical strength and bioactivity for orthopedic implants. Magnesium (Mg), has good bioactivity, biodegradability, and sufficient mechanical properties, similar to that of bone. Moreover, Mg has an inherent antibacterial property via a photothermal effect, which generates localized heat, thus preventing bacterial infection. Therefore, Mg is a good candidate material for PLA composites, to improve their mechanical and biological performance and add an antibacterial property. Herein, we fabricated an antibacterial PLA/Mg composite for enhanced mechanical and biological performance with an antibacterial property for application as biodegradable orthopedic implants. The composite was fabricated with 15 and 30 vol% of Mg homogeneously dispersed in PLA without the generation of a defect using a high-shear mixer. The composites exhibited an enhanced compressive strength of 107.3 and 93.2 MPa, and stiffness of 2.3 and 2.5 GPa, respectively, compared with those of pure PLA which were 68.8 MPa and 1.6 GPa, respectively. Moreover, the PLA/Mg composite at 15 vol% Mg exhibited significant improvement of biological performance in terms of enhanced initial cell attachment and cell proliferation, whereas the composite at 30 vol% Mg showed deteriorated cell proliferation and differentiation because of the rapid degradation of the Mg particles. In turn, the PLA/Mg composites exerted an antibacterial effect based on the inherent antibacterial property of Mg as well as the photothermal effect induced by near-infrared (NIR) treatment, which can minimize infection after implantation surgery. Therefore, antibacterial PLA/Mg composites with enhanced mechanical and biological performance may be a candidate material with great potential for biodegradable orthopedic implants., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Research on regeneration and accelerated recovery processes of bone tissue has driven a growing interest in the scientific community. Implementing natural materials to reduce rejections due to biocompatibility issues is an important trend. Biofunctionalization processes have been proposed to promote osseointegration in implant materials, and those substances able to generate an adequate environment for cell proliferation are the object of several studies. Because of their high protein content and their anti-inflammatory, antibacterial, antimicrobial, and healing properties, microalgae represent a natural source of bioactive compounds, and are proposed as candidates for tissue regeneration applications. In this paper microalgae are reviewed as a source of biofunctionalized materials focused on orthopedic applications.

Autologous adipose stromal vascular fractions (SVFs) containing adipose tissue-derived stem cells (ASCs) are currently being used in clinical settings for various orthopedic applications for human patients. Due to its potential capability of regenerating cartilage, bone, and tendons, autologous adipose SVFs are being tried in treating patients with osteoarthritis (OA), chondromalacia, meniscus tear, osteonecrosis of the femoral head, and tendon injuries. Here, we have reviewed available human clinical studies with regard to patient applications of autologous adipose SVF containing ASCs, specifically assessing effectiveness and safety in the field of orthopedic disorders. All studies reviewed in this article presents potential benefits of autologous adipose SVF in various orthopedic applications without any serious side effects. [ABSTRACT FROM AUTHOR]

A surface coating strategy encompassing the use of bioactive trace elements and reinforcing material will have significant influence on mechanical and osseointegration properties of bioceramic coated implants. Here, We attempted to mimic developed a minerals substituted and graphene oxide reinforced hydroxyapatite (Se,Mn-HAP/GO) composite coating on titanium (Ti) by electrodeposition which is a promising approach to produce bioimplants with better osseointegration capacity and improved mechanical property. Mechanical and biological studies were used to characterise the coatings. The composite coating on Ti was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM). Also, the corrosion resistance of the coatings was evaluated by electrochemical techniques in simulated body fluid (SBF) solution. The in vitro cell-material interaction of the composite coating was observed with human osteosarcoma MG63 cells for cell viability at 1, 2 and 3 days of incubation. From the results we believe that the (Se,Mn-HAP/GO) composite coating on Ti could provide effective corrosion protection, enhanced bioactivity. Thus, composite coated Ti can serve as a potential candidate for orthopedic applications. [ABSTRACT FROM AUTHOR]

Orthopedic applications commonly require the administration of systemic antibiotics. Gentamicin is one of the most commonly used aminoglycosides in the treatment and prophylaxis of infections associated with orthopedic applications, but gentamicin has a short half-life. However, silica nanoparticles (SiO2 NPs) can be used as elegant carriers for antibiotics to prolong their release. Our goal is the preparation and characterization of SiO2-gentamicin nanohybrids for their potential antimicrobial administration in orthopedic applications. In vitro gentamicin release profile from the nanohybrids (gentamicin-conjugated SiO2 NPs) prepared by the base-catalyzed precipitation exhibited fast release (21.4%) during the first 24 h and further extension with 43.9% release during the five-day experiment. Antimicrobial studies of the SiO2-gentamicin nanohybrids versus native SiO2 NPs and free gentamicin were performed against Bacillus subtilis (B. subtilis), Pseudomonas fluorescens (P. fluorescens) and Escherichia coli (E. coli). SiO2-gentamicin nanohybrids were most effective against B. subtilis. SiO2 NPs play no antimicrobial role. Parallel antimicrobial studies for the filter-sterilized gentamicin were performed to assess the effect of ultraviolet (UV)-irradiation on gentamicin. In summary, the initial fast gentamicin release fits the need for high concentration of antibiotics after orthopedic surgical interventions. Moreover, the extended release justifies the promising antimicrobial administration of the nanohybrids in bone applications. [ABSTRACT FROM AUTHOR]

The present work is focused on the fabrication of Bellamya javanica rice fields snail shells derived samarium (Sm) substituted hydroxyapatite (Sm-HAP)/polypyrrole (PPy)/ Wrightia tinctoria fiber (WTF) biocomposite on titanium (Ti) by electrophoretic deposition for orthopedic applications. The functional groups, phase composition, morphology, elemental composition was examined by various characterization techniques. In addition, the adhesion strength and hardness of the biocomposite coatings was evaluated by mechanical characterization. The corrosion behavior of the as developed biocomposite coating on Ti was determined by potentiodynamic polarization study. Similarly, the antimicrobial activity of the biocomposite was evaluated against two bacterial strains and one fungal strain by well diffusion test. The in vitro bioactivity and biocompatibility of the composite was evaluated for the biocomposite coated Ti. Also, the swelling and degradation behavior of the as fabricated coating were examined in simulated body fluid medium. Hence, from the obtained results it can be concluded that the Sm-HAP/PPy/ WTF biocomposite coated Ti exhibited excellent anticorrosion, anti-microbial and biocompatible properties which make them a potential material for high-performance bone implants in the field of orthopedic applications. • Sm-HAP is derived from natural biowaste ie. , Bellamya javanica rice fields snail shells. • Sm-HAP/PPy/ WTF biocomposite on titanium (Ti) by electrophoretic deposition. • Sm-HAP and WTF improves antibacterial and bioactive property. • Sm-HAP/PPy/ WTF biocomposite coated Ti have excellent anticorrosion, anti-microbial and biocompatible properties. [ABSTRACT FROM AUTHOR]

Schematic graphical representation of the Strontium doped Hydroxyapatite/ Chitosan/Polypyrrole/TNT on titanium alloy. [Display omitted] • Chitosan-polypyrrole matrix composite was prepared by electrophoretic deposition way. • TNT/CS-PPy@Sr-HAP coated Ti shows suitable mechanical strength and micro-hardness. • Also exhibits in bone regeneration ability in MG63 cell lines studies. • Composite shows better in-vitro cell growth and anti-bacterial activity. This study aimed to investigate the effects of TNT/CS-PPy@Sr-HAP composite coatings on Ti alloys that were used to develop the coating by anodization via electrophoretic deposition method. The formation of TNT/CS-PPy@Sr-HAP composite coatings was characterized by FT-IR, XRD, and FESEM with EDAX analyses. The mechanical performance of the composite coating was investigated for its thickness, microhardness, and adhesion tests. Antibacterial tests showed that TNT/CS-PPy@Sr-HAP (II) composite coated sample recorded the maximum level of antimicrobial activity against E. coli and S. aureus bacteria was found to be 25 & 22 mm for 100 μL samples, respectively. The in vitro studies confirmed that TNT/CS-PPy@Sr-HAP (II) composite coating exhibited a greater number of viable cells found to be ∼99.7% after 7 days of incubation. Potentiodynamic polarization and electrochemical impedance studies were performed on TNT/CS-PPy@Sr-HAP (II) composite coatings resulting in its better corrosion behavior when compared to other coatings. All these results show that TNT/CS-PPy @ Sr-HAP (II) composite coated on Ti implant alloy will serve as a potential material for orthopedic applications. [ABSTRACT FROM AUTHOR]

Abstract: The high corrosion rate of Mg alloys has hindered their application in various areas, particularly for orthopedic applications. In order to decrease the corrosion rate and to improve the bioactivity, mechanical stability and cytocompatibility of the Mg alloy, nanostructured diopside (CaMgSi2O6) has been coated on AZ91 Mg alloy using a combined micro arc oxidation (MAO) and electrophoretic deposition (EPD) method. The crystalline structure, the morphology and the composition of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Electrochemical corrosion test, immersion test, and compression test were used to evaluate the corrosion resistance, the in vitro bioactivity and the mechanical stability of the samples, respectively. The cytocompatibility of the samples was tested by the cell viability and the cell attachment of L-929 cells. The results confirmed that the diopside coating not only slows down the corrosion rate, but also enhances the in vitro bioactivity, mechanical stability and cytocompatibility of AZ91 Mg alloy. Therefore, Mg alloy coated with nanostructured diopside offers a promising approach for biodegradable bone implants. [Copyright &y& Elsevier]

Abstract: Ti-based metallic glasses show high potential for implant applications; they overcome in several crucial respects their well-established biocompatible crystalline counterparts, e.g. improved corrosion properties, higher fracture strength and wear resistance, increased elastic strain range and lower Young''s modulus. However, some of the elements required for glass formation (e.g. Cu, Ni) are harmful for the human body. We critically reviewed the biological safety and glass forming tendency in Ti of 27 elements. This can be used as a basis for the future designing of novel amorphous Ti-based implant alloys entirely free of harmful additions. In this paper, two first alloys were developed: Ti75Zr10Si15 and Ti60Nb15Zr10Si15. The overheating temperature of the melt before casting can be used as the controlling parameter to produce fully amorphous materials or bcc-Ti-phase reinforced metallic glass nano-composites. The beneficial effect of Nb addition on the glass-formation and amorphous phase stability was assessed by X-ray diffraction, transmission electron microscopy and differential scanning calorimetry. Crystallization and mechanical behavior of ribbons are influenced by the amount and distribution of the nano-scaled bcc phase existing in the as-cast state. Their electrochemical stability in Ringer''s solution at 310K was found to be significantly better than that of commercial Ti-based biomaterials; no indication for pitting corrosion was recorded. [Copyright &y& Elsevier]

Abstract: The corrosion behavior of magnesium and its alloys in the electrolytic physiological environment is extremely poor; this imposes a limitation for their use in orthopedic applications. In the present study, the effect of spray coating AZ31 magnesium alloy with membrane films of pristine and hydroxyapatite-doped poly(lactic acid) on corrosion behavior and bioactivity is investigated. Polymer concentration was found to have a strong impact on the pore size of the coating layer. However, addition of HAp NPs distinctly stimulated the precipitation of an apatite-like compound upon soaking the samples in a simulated body fluid (SBF). Magnesium coated samples revealed three orders of magnitude less corrosion compared to the naked samples, which indicates a stable electrochemical corrosion resistance. During a 15 days in-vitro test, pH variation, weight loss, and bending strength were lower for the coated samples (with average values of 8.5%, 7.2% and 10%, respectively) than the control sample (10.5%, 15.5%, and 25%, respectively). Moreover, the coated samples showed good bending strength characteristics. Cytocompatibility studies on MC3T3 cells revealed a continuous increase in cell growth with the coated samples. Overall, the suggested strategy might open a new avenue to widen utilization of Mg alloys as implant materials for orthopedic applications. [Copyright &y& Elsevier]

Abstract: This paper presents the results of a laser-based combinatorial investigation of the Ti–Mo system, aiming at finding alloys with promising properties for orthopedic applications. Variable powder feed rate laser cladding was applied to synthesize Ti–xMo alloys with composition continuously varying in the range of 4–19wt.% Mo. Screening was performed on the basis of the alloys'' mechanical properties, in particular hardness and Young''s modulus, measured by microindentation tests. Microstructural analysis showed that alloys with Mo content between 4 and 8wt.% are composed of acicular martensite and retained β-phase, the proportion of the later phase increasing with increasing Mo content. Alloys with Mo content of 10wt.% and higher consist entirely of β phase. All the alloys present a Mo segregation pattern indicating that solidification occurred with a cellular solid–liquid interface. Though β-phase alloys present lower values of Young''s modulus and hardness than α′- or α″- containing alloys, minimum values of Young''s modulus (75GPa) and hardness (240VHN) were achieved for the Ti–13wt.% Mo alloy. [Copyright &y& Elsevier]

Vitallium-2000 Plus alloy is one of the important metallic biomaterials having excellent biocompatibility as it is free from nickel, vanadium, and beryllium elements that could cause potential allergic problems to patients. In this study, the high cycle fatigue behavior of continuous cast vitallium-2000 Plus alloy was investigated using rotation bend fatigue tests at 50 Hz frequency and at room temperature apart from tensile studies. A series of tests were carried out at varying stresses, and the S-N curve was obtained from regression of the test data. The endurance limit was determined as 387 MPa, which is very good for a cast alloy. This increase in fatigue property (compared to the previous version of this alloy) is primarily due to the presence of nitrogen that is added during continuous casting process and also that of the other alloying elements. Tensile test was also performed as per the ASTM standard to evaluate its static properties. The fracture morphology was investigated using scanning electron microscope to study the mechanisms of fracture. It was established that the primary mechanism of fracture was by microvoid nucleation and coalescence, typical of a ductile material that is significant for a cast alloy. The experimentally determined values of endurance limit, yield strength, tensile strength, and percent elongation provide evidence that vitallium-2000 Plus cast alloy has very good fatigue, tensile properties, and increased formability without fracture, allowing for excellent adjustability during its application. [ABSTRACT FROM AUTHOR]