Orthopedic Implants Research Articles

Preparation and Biological Evaluation of Porous Tantalum Scaffolds Coated with Hydroxyapatite.

Orthopedic implants, such as porous scaffolds, are an effective way to repair bone defects. However, the lack of osseointegration and osteoinduction limits the achievement of an ideal therapeutic effect. This study aimed to prepare hydroxyapatite (HA) coatings for the surface of porous tantalum (Ta) scaffolds and to assess the effectively improved biological activities of the coated scaffolds. The porous Ta scaffolds were prepared by chemical vapor deposition, and then the porous Ta scaffolds were coated with HA via electrochemical deposition. The elements and phase compositions of the coatings were analyzed by energy-dispersive X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The results showed that the coating covered the whole surfaces of porous Ta scaffolds with a uniform and compact distribution and did not exert any obvious effect on the porous structure. The biological activity of porous Ta scaffolds after surface modification increased and the water contact angle decreased, indicating that hydrophilicity was significantly improved. Cell live/dead staining, cytoskeletal fluorescence staining, and alkaline phosphatase immunofluorescence staining showed that the coating exhibited no cytotoxicity and notably improved cell proliferation, spreading, and osteogenic differentiation. In addition, in vivo experiments in animals have demonstrated that HA-coated porous Ta scaffolds contribute to bone formation. In conclusion, the HA coating notably improves the biological activities of the porous Ta scaffolds, achieving the goal of the present study. The HA coating presents great potential for the modification of porous Ta implants to improve their osteogenesis and osseointegration.

Bacteriological spectrum of infections in orthopaedic implants and their antibiotic susceptibility pattern

Bacteriological spectrum of infections in orthopaedic implants and their antibiotic susceptibility pattern

Biodegradable oxygen-evolving metalloantibiotics for spatiotemporal sono-metalloimmunotherapy against orthopaedic biofilm infections

Pathogen-host competition for manganese and intricate immunostimulatory pathways severely attenuates the efficacy of antibacterial immunotherapy against biofilm infections associated with orthopaedic implants. Herein, we introduce a spatiotemporal sono-metalloimmunotherapy (SMIT) strategy aimed at efficient biofilm ablation by custom design of ingenious biomimetic metal-organic framework (PCN-224)-coated MnO2-hydrangea nanoparticles (MnPM) as a metalloantibiotic. Upon reaching the acidic H2O2-enriched biofilm microenvironment, MnPM can convert abundant H2O2 into oxygen, which is conducive to significantly enhancing the efficacy of ultrasound (US)-triggered sonodynamic therapy (SDT), thereby exposing bacteria-associated antigens (BAAs). Moreover, MnPM disrupts bacterial homeostasis, further killing more bacteria. Then, the Mn ions released from the degraded MnO2 can recharge immune cells to enhance the cGAS-STING signaling pathway sensing of BAAs, further boosting the immune response and suppressing biofilm growth via biofilm-specific T cell responses. Following US withdrawal, the sustained oxygenation promotes the survival and migration of fibroblasts, stimulates the expression of angiogenic growth factors and angiogenesis, and neutralizes excessive inflammation. Our findings highlight that MnPM may act as an immune costimulatory metalloantibiotic to regulate the cGAS-STING signaling pathway, presenting a promising alternative to antibiotics for orthopaedic biofilm infection treatment and pro-tissue repair.

Mechanical study reinforced magnesium-yttrium alloys by eggshell powder using resistance casting

Magnesium-based alloys are relatively new materials for orthopedic implants. One common component that makes magnesium-based alloys biocompatible and chemically stable is the addition of minor compositions of rare earth metals like yttrium to anchor other chemically active components. From an orthopedic perspective, two goals are of primary concern. One is sufficient mechanical support to stabilize the fracture and reduce inflammation. Another is assistance for the transition of osteogenesis and intramembranous ossification for bone production and remodeling. To attain both goals and further improve the current magnesium-yttrium alloys, adding extra ingredients to improve osseointegration is a common and effective approach. By the nature of bone chemistry, calcium is the top choice as calcium is the key element in maintaining bone integrity and biochemical metabolism. In this study, the mechanical behaviors of a calcium-added magnesium-based alloy (Mg-Y3.5 wt%) are investigated by experiments. This inventive idea for the natural source of calcium is obtained from chicken eggs due to their (1) cost-effective and abundant availability, and (2) naturally synthesized calcium carbonate along with a minor content of organic materials. The fabrication processes involved are the ball-milling of eggshells as an additive at 1, 3, and 5 wt%. into magnesium-yttrium alloys and resistance casting to form composites. Material characterization includes microstructural analysis by X-ray diffraction, morphological/elemental analysis via optical microscopy, field emission scanning electron microscopes, energy-dispersive X-ray spectroscopy, mechanical properties by uniaxial compression and Vickers microhardness tests. Experimental results supplemented by statistical and finite element analysis indicate that the new composite exhibits enhanced ductility; and the 3 wt% eggshell-added alloys show better reinforcement of mechanical properties among all samples with an ultimate compression strength of 161.19 MPa, maximum elongation of 17.53 %, and hardness of 457.48 (N/mm2). Note that the comparable mechanical strength of the composite to that of human bones could reduce the stress shielding on bones and further help the process of bone remodeling.

Compressive properties and biocompatibility of additively manufactured lattice structures by using bioactive materials

Porous bioactive materials were widely used in orthopedic implant fields because of their excellent mechanical properties and porous spaces. However, most porous types are predominantly stacked in two-dimensional configurations, which significantly limits their mechanical property range and adversely affects the modulus matching between the porous implants and surrounding bone tissues. Hence, various lattice structures were prepared using 3D printing technology with bioactive materials, and characterized by mechanical and biological tests. Numerical simulations were conducted to analyze the effect of relative density and geometric parameters on the equivalent compressive properties of the lattice structures. The results showed that the lattice structure exhibited a broad elastic modulus range, which can be adjusted to align with the mechanical properties of human cortical and cancellous bones, thereby helping to mitigate stress shielding in orthopedic implants. The biocompatibility of the 3D-printed solid materials was assessed in vitro using a cell counting assay kit-8 (CCK-8). The results indicated that poly-ether-ether-ketone (PEEK), carbon fiber reinforced PEEK (CFR/PEEK), nylon, and titanium (Ti) alloy all exhibited good biocompatibility, with no significant differences observed among the four materials. This study further enhances the understanding of bioactive lattice structures in the biomedical field and offers new possibilities for orthopedic repair.

3D-ink-extruded titanium scaffolds with porous struts and bioactive supramolecular polymers for orthopedic implants

Porous titanium addresses the longstanding orthopedic challenges of aseptic loosening and stress shielding. This work expands on the evolution of porous Ti with the manufacturing of hierarchically porous, low stiffness, ductile Ti scaffolds via direct-ink write (DIW) extrusion and sintering of inks containing Ti and NaCl particles. Scaffold macrochannels were filled with a subtherapeutic dose of recombinant bone morphogenetic protein-2 (rhBMP-2) alone or co-delivered within a bioactive supramolecular polymer slurry (SPS) composed of peptide amphiphile nanofibrils and collagen, creating four treatment conditions (Ti struts: microporous vs. fully dense; BMP-2 alone or with SPS). The BMP-2-loaded scaffolds were implanted bilaterally across the L4 and L5 transverse processes in a rat posterolateral lumbar fusion model. In-vivo bone growth in these scaffolds is evaluated with synchrotron X-ray computed microtomography (µCT) to study the effects of strut microporosity and added biological signaling agents on the bone formation response. Optical and scanning electron microscopy confirms the ∼100 µm space-holder micropore size, high-curvature morphology, and pore fenestrations within the struts. Uniaxial compression testing shows that the microporous strut scaffolds have low stiffness and high ductility. A significant promotion in bone formation was observed for groups utilizing the SPS, while no significant differences were found for the scaffolds with the incorporation of micropores. Statement of significanceBy 2050, the anticipated number of people aged 60 years and older worldwide is anticipated to double to 2.1 billion. This rapid increase in the geriatric population will require a corresponding increase in orthopedic surgeries and more effective materials for longer indwelling times. Titanium alloys have been the gold standard of bone fusion and fixation, but their use has longstanding limitations in bone-implant stiffness mismatch and insufficient osseointegration. We utilize 3D-printing of titanium with NaCl space holders for large- and small-scale porosity and incorporate bioactive supramolecular polymers into the scaffolds to increase bone growth. This work finds no significant change in bone ingrowth via space-holder-induced microporosity but significant increases in bone ingrowth via the bioactive supramolecular polymers in a rat posterolateral fusion model.

Sol-Gel SiO2 Coatings with Curcumin and Thymol on 3D Printouts Manufactured from Ti6Al4V ELI

Bacterial biofilm on implants may cause inflammation, which disturbs the process of the implant’s integration with the surrounding tissues. Such problems are becoming critical for patients’ health, especially in connection with the presence of antibiotic-resistant bacterial strains. Among the existing alternatives for drug treatments are natural-based substances. This study focused on the examination of silica coatings with curcumin and thymol, which were deposited using the sol-gel method on 3D printouts made of Ti6Al4V ELI. This substrate material is commonly used in medicine. The selective laser melting technique used for the manufacturing of samples was in line with the existing procedures applied for individual orthopedic implants. The examination involved the assessment of the coatings’ morphology, chemical composition, and biological effect. The antibacterial properties were tested using a flow cytometer using Escherichia coli, and the cytotoxicity on Saos-2 cells was assessed using the LIVE/DEAD test. The obtained results showed that it is possible to produce silica sol-gel coatings with the addition of specific natural substances in concentrations assuring a bacteriostatic effect. The produced coatings did not show any cytotoxic effect, which confirms the possibility of using both curcumin and thymol as additives to coatings used in medicine, e.g., for orthopedic implants.

Thermal and Mechanical Mechanisms of Polymer Wear at the Nanoscale.

Wear is a ubiquitous phenomenon that limits the life of many engineered components with sliding interfaces through the gradual removal of material. The wear of polymers is crucial in many applications, ranging from bearings to orthopedic implants to nanolithography processes. The wear rate of polymers is strongly affected by the stress and temperature at the interface. The effects of temperature and stress are often described empirically since the wear process involves complex interactions between multiple asperities on rough surfaces over a range of length scales. Nanoscale tribology experiments at the single-asperity level have provided new insights into the underlying mechanisms of wear. Experiments on hard covalently bonded materials, including silicon and diamond, have demonstrated that wear is an atomic attrition wear process that can be modeled using stress-assisted transition state theory. Here, we examine the wear of a common polymer, polymethylmethacrylate (PMMA), at the nanoscale as a function of stress and temperature and show that the polymer wear is controlled by a combination of atomic attrition and viscoelastic relaxation. While the wear experiments are conducted at the nanoscale via atomic force microscopy, the results show that accounting for the local stress distribution at the contact interface is critical to understanding the wear behavior, an effect that was not considered in earlier studies on hard materials. Using a model that accounts for the stress distribution, we demonstrate the ability to predict the wear volume within 8%.

Zinc, Magnesium and Tantalum for biomedical applications: A comprehensive review

The historical development and biomedical applications of magnesium, tantalum, and zinc are examined in this integrated study. It traces the development of magnesium from its use in military applications through its integration into many businesses, with an emphasis on its use in orthopaedic implants. Along with early attempts and failures in orthopaedic implantation, the mechanical properties of magnesium alloys suitable for biodegradable osteosynthetic materials are investigated. Clinical cases highlighting the successes and difficulties of magnesium implants in bone restoration are presented. Magnesium alloys have recently played important roles in biomedicine, particularly in stents and scaffolds. This analysis highlights their biocompatibility and corrosion behaviour. The numerous biomedical applications of tantalum and zinc, such as those in implants, surgical equipment, and drug delivery, are then discussed. Tantalum's porosity, biocompatibility, and biomechanical qualities make it the ideal material for implants, producing positive results in bone, tissue, and dental applications. Zinc's robust antibacterial characteristics and promise in targeted drug release are highlighted. Innovative manufacturing techniques, composite optimisation, surface alterations, and thorough clinical assessments are among the future directions. Key areas of interest include standardised testing, tissue interactions, and regulatory frameworks. This paper highlights the crucial contributions of tantalum, magnesium, and zinc to the development of biomedical engineering and provides insights for improved patient care, innovation, and therapeutic efficacy.

A comparative study on the effects of biodegradable high-purity magnesium screw and polymer screw for fixation in epiphyseal trabecular bone.

With mechanical strength close to cortical bone, biodegradable and osteopromotive properties, magnesium (Mg)-based implants are promising biomaterials for orthopedic applications. However, during the degradation of such implants, there are still concerns on the potential adverse effects such as formation of cavities, osteolytic phenomena and chronic inflammation. Therefore, to transform Mg-based implants into clinical practice, the present study evaluated the local effects of high-purity Mg screws (HP-Mg, 99.99 wt%) by comparing with clinically approved polylactic acid (PLA) screws in epiphyseal trabecular bone of rabbits. After implantation of screws at the rabbit distal femur, bone microstructural, histomorphometric and biomechanical properties were measured at various time points (weeks 4, 8 and 16) using micro-CT, histology and histomorphometry, micro-indentation and scanning electron microscope. HP-Mg screws promoted peri-implant bone ingrowth with higher bone mass (BV/TV at week 4: 0.189 ± 0.022 in PLA group versus 0.313 ± 0.053 in Mg group), higher biomechanical properties (hardness at week 4: 35.045 ± 1.000 HV in PLA group versus 51.975 ± 2.565 HV in Mg group), more mature osteocyte LCN architecture, accelerated bone remodeling process and alleviated immunoreactive score (IRS of Ram11 at week 4: 5.8 ± 0.712 in PLA group versus 3.75 ± 0.866 in Mg group) as compared to PLA screws. Furthermore, we conducted finite element analysis to validate the superiority of HP-Mg screws as orthopedic implants by demonstrating reduced stress concentration and uniform stress distribution around the bone tunnel, which led to lower risks of trabecular microfractures. In conclusion, HP-Mg screws demonstrated greater osteogenic bioactivity and limited inflammatory response compared to PLA screws in the epiphyseal trabecular bone of rabbits. Our findings have paved a promising way for the clinical application of Mg-based implants.

Modified implant with dual functions of antioxidant and extracellular matrix reconstruction for regulating MSCs senescence

Bone repair in elderly patients is significantly weaker compared to normal bone repair, and one of the main reasons for this is the senescence of bone marrow mesenchymal stem cells (MSCs), which play a key role in the bone repair process. Therefore, we considered the corresponding surface modification of orthopedic implants to cope with the practical problem of bone defects in elderly patients. In this thesis, we prepared TiO2 nanotubes loaded with metformin (Glucophage) on Ti substrates, followed by self-assembly layer by layer using chitosan-catechol and gelatin on the surface, to delay MSCs senescence by eliminating excessive reactive oxygen species (ROS) and reconstructing extracellular matrix (ECM), thereby achieving osteogenesis. The results showed a significant reduction in senescence-associated secretory phenotype (SASP) generation, an enhancement of PINK1/Parkin-mediated mitochondrial autophagy, and a decrease in intracellular and extracellular ROS levels in MSCs under the dual effects of antioxidants and ECM reconstruction, suggesting that the degree of senescence in MSCs was significantly reduced. Osteogenesis was also demonstrated by expression of osteogenesis-related genes and staining of animal sections. In conclusion, our material can indeed promote the proliferation and osteogenic differentiation of MSCs by delaying cellular senescence, which is expected to provide a novel approach for clinical solutions to tissue repair problems in elderly patients with bone defects.

SrHPO4-coated Mg alloy implant attenuates postoperative pain by suppressing osteoclast-induced sensory innervation in osteoporotic fractures

Osteoporotic fractures have become a common public health problem and are usually accompanied by chronic pain. Mg and Mg-based alloys are considered the next-generation orthopedic implants for their excellent osteogenic inductivity, biocompatibility, and biodegradability. However, Mg-based alloy can initiate aberrant activation of osteoclasts and modulate sensory innervation into bone callus resulting in postoperative pain at the sequential stage of osteoporotic fracture healing. Its mechanism is going to be investigated. Strontium hydrogen phosphate (SrHPO4) coating to delay the Mg-based alloy degradation, can reduce the osteoclast formation and inhibit the growth of sensory nerves into bone callus, dorsal root ganglion hyperexcitability, and pain hypersensitivity at the early stage. Liquid chromatography-mass spectrometry (LC-MS) metabolomics analysis of bone marrow-derived macrophages (BMMs) treated with SrHPO4-coated Mg alloy extracts shows the potential effect of increased metabolite levels of AICAR (an activator of the AMPK pathway). We demonstrate a possible modulated secretion of AICAR and osteoclast differentiation from BMMs, which inhibits sensory innervation and postoperative pain through the AMPK/mTORc1/S6K pathway. Importantly, supplementing with AICAR in Mg-activated osteoclasts attenuates postoperative pain. These results suggest that Mg-induced postoperative pain is related to the osteoclastogenesis and sensory innervation at the early stage in the osteoporotic fractures and the SrHPO4 coating on Mg-based alloys can reduce the pain by upregulating AICAR secretion from BMMs or preosteoclasts.

Biomimetic Surface Nanoengineering of Biodegradable Zn‐Based Orthopedic Implants for Enhanced Biocompatibility and Immunomodulation

AbstractZinc (Zn) is gaining increased recognition as a biodegradable metal in biomedical applications but clinical translation is limited due to its poor biocompatibility. This study addresses these issues through an innovative biomimetic strategy, introducing an efficient surface nanoengineering approach that creates nano‐geometric features and chemical compositions by modulating the exposure time to a biological medium – Dulbecco's Modified Eagle Medium(DMEM). These nanoengineered Zn implants exhibited tunable degradation rates. The nanostructures enhanced human osteoblast attachment, proliferation, and differentiation following direct contact, and improved macrophage function by promoting pseudopod formation and transitioning from a pro‐inflammatory M1 to a pro‐reparative M2 phenotype. In vivo studies show that the surface‐engineered implants effectively promoted tissue integration via M2 macrophage polarization, resulting in a favorable immunomodulatory environment, and increased collagen deposition. Proteomic analyses show that the tissues in the vicinity of the surface‐engineered Zn implants are enriched with proteins related to key wound healing biological mechanisms such as cell adhesion, cytoskeletal structural arrangement, and immune response. This study highlights the improved biocompatibility and anti‐inflammatory effects of surface‐engineered Zn, with important implications for the clinical translation of biodegradable Zn‐based orthopedic implants.

Creating an extracellular matrix-like three-dimension structure to enhance the corrosion resistance and biological responses of titanium implants

Background/purposeTitanium (Ti) is extensively used in dental and orthopedic implants due to its excellent mechanical properties. However, its smooth and biologically inert surface does not support the ingrowth of new bone, and Ti ions may have adverse biological effects. The purpose is to improve the corrosion resistance of titanium and create a 3D structured coating to enhance osseointegration through a very simple and fast surface treatment. Materials and methodsThis study investigated the use of sandblasting, acid etching, and NaOH leaching to produce porous Ti implants with enhanced biological activity and corrosion resistance. ResultsThese surface modifications generated a mixed oxide layer resembling the extracellular matrix (ECM), consisting of a dense amorphous TiO2 inner layer (50–100 nm thick) and a TiO2 outer layer with interconnected pores (pore size 50–500 nm; 150–200 nm thick). The inner layer significantly improved corrosion resistance, while the hydrophilic outer layer, with its porous structure, facilitated protein albumin adsorption and promoted the attachment, proliferation, and mineralization of human bone marrow mesenchymal stem cells. ConclusionThe combined surface treatment approach of sandblasting, acid etching, and NaOH leaching offers a comprehensive solution to the challenges associated with titanium implants' biological inertness and corrosion susceptibility. By enhancing both the biological activity and corrosion resistance of Ti surfaces, this protocol holds significant promise for improving dental and orthopedic implants' success rates and longevity. Future studies should focus on in vivo assessments and long-term clinical trials to further validate these findings and explore the potential for widespread clinical adoption.

Hybrid zinc oxide nanocoating on titanium implants: Controlled drug release for enhanced antibacterial and osteogenic performance in infectious conditions

Implant-associated bacterial infections are a primary cause of complications in orthopedic implants, and localized drug delivery represents an effective mitigation strategy. Drawing inspiration from the morphology of desiccated soil, our group has developed an advanced drug-delivery system augmented onto titanium (Ti) plates. This system integrates zinc oxide (ZnO) nanorod arrays with a vancomycin drug layer along with a protective Poly(lactic-co-glycolic acid) (PLGA) coating. The binding between the ZnO nanorods and the drug results in attached drug blocks, isolated by desiccation-like cracks, which are then encapsulated by PLGA to enable sustained drug release. Additionally, the release of zinc ions and the generation of reactive oxygen species (ROS) from the ZnO nanorods enhance the antibacterial efficacy. The antibacterial properties of ZnO nanorod-drug-PLGA system have been validated through both in vitro and in vivo studies. Comprehensive investigations were conducted on the impact of bacterial infections on bone defect regeneration and the role of this drug-delivery system in the healing process. Furthermore, the local immune response was analyzed and the immunomodulatory function of the system was demonstrated. Overall, the findings underscore the superior performance of the ZnO nanorod-drug-PLGA system as an efficient and safe approach to combat implant-associated bacterial infections. Statement of significanceImplant-associated bacterial infections pose a significant clinical challenge, particularly in orthopedic procedures. To address this, we developed an innovative ZnO nanorod-drug-PLGA system for local antibiotic delivery on conventional titanium implants. This system is biodegradable and features a unique desiccation-like structure that enables sustained drug release, along with the active substances released from the ZnO nanorods. In a rat calvarial defect model challenged with S. aureus, our system demonstrated remarkable antibacterial efficacy, significantly enhanced bone defect regeneration, and exhibited local immunomodulatory effects that support both infection control and osteogenesis. These breakthrough findings highlight the substantial clinical potential of this novel drug delivery system and introduce a transformative coating strategy to enhance the functionality of traditional metallic biomaterials.

Characterisation of 3D-printed acetabular hip implants.

Three-dimensional printing is a rapidly growing manufacturing method for orthopaedic implants and it is currently thriving in several other engineering industries. It enables the variation of implant design and the construction of complex structures which can be exploited in orthopaedics and other medical sectors. In this review, we develop the vocabulary to characterise 3D printing in orthopaedics from terms defined by industries employing 3D printing, and by fully examining a 3D-printed off-the-shelf acetabular cup (Fig. 1). This is a commonly used 3D-printed implant in orthopaedics, and it exhibits a range of prominent features brought about by 3D printing. The key features and defects of the porous and dense regions of the implant are clarified and discussed in depth to determine reliable definitions and a common understanding of characteristics of 3D printing between engineers and medical experts in orthopaedics. Despite the extensive list of terminology derived here, it is clear significant gaps exist in the knowledge of this field. Therefore, it is necessary for continued investigations of unused implants, but perhaps more significantly, examining those in vivo and retrieved to understand their long-term impact on patients and the effects of certain features (e.g. surface-adhered particles). Analyses of this kind will establish an understanding of 3D printing in orthopaedics and additionally it will help to update the regulatory approach to this new technology.

Study on performance regulation of electro-mechanical properties 3D printed BaTiO3/HA porous structure composite ceramic

BaTiO3/Ca10(PO4)6(OH)2 composite ceramic is an outstanding representative of piezoelectric biomaterials, with excellent biocompatibility and piezoelectric effect, and has potential applications in the field of bone tissue repair. In this work, vat photopolymerization 3D printing technology was used to fabricate triply periodic minimal surface structure BaTiO3/Ca10(PO4)6(OH)2 composite ceramic bone tissue scaffolds with different pore sizes and porosity, and their mechanical and electrical properties were studied. First, the ceramic slurry configuration process was optimized to obtain a ceramic slurry with high solid content (45 vol%) and excellent rheological properties. Then the effect of sintering temperature on microstructure, relative density, mechanical properties, and electrical properties is discussed. The results show that when sintering at 1300 °C, the BaTiO3/Ca10(PO4)6(OH)2 composite ceramic has the highest relative density (99.18 %), the highest compressive strength (44 MPa), large relative dielectric constant (379–389), and low dielectric loss. The polarization electric field strength of the BaTiO3/Ca10(PO4)6(OH)2 composite ceramic was set to 15 kV/cm through the test of the hysteresis loop. Finally, based on multi-physics coupled finite element simulation, the effects of different porosity and different pore sizes on stress distribution and piezoelectric potential were analyzed, and the relationship between them was explored through experiments. The results show that as the porosity increases and the pore size decreases, the mechanical properties of the scaffold decrease significantly, and its compressive strength ranges between 1.67 and 4.26 MPa; as the porosity increases and the pore size increases, the piezoelectric coefficient (d33) of the scaffold showed a decreasing trend, and its d33 ranged between 2 and 9 pC/N. The mechanical and electrical properties of the scaffold meet the performance requirements of cancellous bone. In summary, this work provides a strategy for the application of customized BaTiO3/Ca10(PO4)6(OH)2 composite ceramic scaffolds in new-generation orthopedic implants.

Stress-shielding in aseptic loosening on the 3D printed acetabular cup in hip arthroplasty: review article

The increasing number of prosthetic hip replacement surgeries and their growing indication have led to a growing interest in understanding the factors that influence their long-term success. Total hip arthroplasty (THA) failure is mainly due to aseptic loosening. More rarely septic mobilization may occur. In the first case, many variables influence the bone-implant relationship and periprosthetic bone remodeling. Stress-shielding is the most evident but not fully explained manifestation of the bone implant interaction. Recently, three-dimensional (3D) printed titanium orthopedic implants have offered new perspectives in the field of hip prosthetics, enabling the customization and production of acetabular cups with enhanced biocompatibility. This review aims to evaluate the efficacy and reliability of 3D printed acetabular cups from the perspective of aseptic failure particularly related to the stress-shielding. The most recent clinical and preclinical studies will be reviewed, exploring the benefits and challenges associated with the use of these emerging technologies. Key factors, such as biocompatibility, mechanical stability, osseointegration, and wear resistance.

Titanium nanoparticles released from orthopedic implants induce muscle fibrosis via activation of SNAI2

Titanium alloys represent the prevailing material employed in orthopedic implants, which are present in millions of patients worldwide. The prolonged presence of these implants in the human body has raised concerns about possible health effects. This study presents a comprehensive analysis of titanium implants and surrounding tissue samples obtained from patients who underwent revision surgery for therapeutic reasons. The surface of the implants exhibited nano-scale corrosion defects, and nanoparticles were deposited in adjacent samples. In addition, muscle in close proximity to the implant showed clear evidence of fibrotic proliferation, with titanium content in the muscle tissue increasing the closer it was to the implant. Transcriptomics analysis revealed SNAI2 upregulation and activation of PI3K/AKT signaling. In vivo rodent and zebrafish models validated that titanium implant or nanoparticles exposure provoked collagen deposition and disorganized muscle structure. Snai2 knockdown significantly reduced implant-associated fibrosis in both rodent and zebrafish models. Cellular experiments demonstrated that titanium dioxide nanoparticles (TiO2 NPs) induced fibrotic gene expression at sub-cytotoxic doses, whereas Snai2 knockdown significantly reduced TiO2 NPs-induced fibrotic gene expression. The in vivo and in vitro experiments collectively demonstrated that Snai2 plays a pivotal role in mediating titanium-induced fibrosis. Overall, these findings indicate a significant release of titanium nanoparticles from the implants into the surrounding tissues, resulting in muscular fibrosis, partially through Snai2-dependent signaling.Graphical

Direct CVD graphene growth onto surgical stainless steel for orthopedic implants

Graphene sheets were successfully grown for the first time on the surface of surgical stainless steel cylinders by direct APCVD process using methane, argon and hydrogen as precursor gases and without the addition of metal catalyst. The effects of deposition temperature, deposition time, and oxidation minimization through pre-vacuum processes, along with the use of an optimized sample holder, were analyzed. The obtained results are supported by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) characterization techniques. These graphene covered cylinders are intended to be used as orthopedic implants and are going to be tested initially in rats.