Orthopedic Implants Research Articles

Aqueous electrophoretic deposition of yttrium-doped nanobioactive glass/collagen/chitosan orthopedic coatings on 316L SS

The current study used yttrium-doped nanobioactive glass (Y-nBG), based on 62 SiO2 – (33 – x) CaO – 5 P2O5 – x Y2O3 mole % system (x = 0 and 3 mol %), collagen, and chitosan composites for coating 316L stainless steel (316L SS) using aqueous electrophoretic deposition (EPD) technique. The corresponding coated samples are encoded as SS/Col-Chit, SS/BG-Y0/Col-Chit, and SS/BG-Y3/Col-Chit, respectively. Physicochemical characterization implied TGA, FTIR, SEM-EDX, contact angle, adhesion strength and in vitro bioactivity in SBF were performed. Following SBF immersion, FTIR and SEM-EDX investigations were also carried out. Furthermore, the coatings were loaded with gentamicin drug; the drug-release profile and mechanism were evaluated. The antibacterial efficacy of the composite coatings was also assessed. The results showed the formation of homogeneous coatings with good adhesion strength, 1.39 MPa, 0.55 MPa, and 0.81 MPa, and enhanced the wettability by decreasing the contact angle 36⁰, 22⁰ and 12⁰ for SS/Col-Chit, SS/BG-Y0/Col-Chit and SS/BG-Y3/Col-Chit coatings, respectively. In vitro bioactivity of coatings containing nBG revealed apatite formation after immersion in SBF. Furthermore, the antibiotic gentamicin showed a sustained release profile over time by diffusion mechanisms based on the Higuchi, Fickian, and Weibull models. As well, all coatings containing drugs have an antibacterial effect. Overall, these findings suggested that the prepared coatings have potential applications as orthopedic and dental implants.

CT-based measurement and analysis of distal humerus morphology in healthy adults from Northern China

BackgroundThis study aims to investigate the morphological characteristics of the distal humerus in healthy adults from northern China using computed tomography and three-dimensional reconstruction techniques and compared whether there were diferences in morphology among populations from diferent geographical regions.MethodsThe CT data of 80 patients were imported into Mimics software for three-dimensional reconstruction and measurement. The differences in distal humeral morphological parameters between different genders and sides were compared, and the correlation between the parameters was explored. The distal humeral morphological parameters between Western and Chinese populations based on current and previous pooled results were compared.ResultsThirty-one morphological parameters were measured and analyzed in this study. The average (and standard deviation) of capitellum depth, capitellum width, capitellum height, distal humerus width, epitrochlea width, and humeral metaphyseal width was 10.83 ± 1.18 mm, 17.60 ± 2.06 mm, 21.10 ± 2.03 mm, 44.38 ± 4.07 mm, 12.02 ± 1.90 mm and 58.95 ± 4.86 mm, these parameters were significantly higher (P < 0.001*) in males than females. The capitellum width (r = -0.300, P = 0.007*), anterior lateral trochlear depth (r =-0.227, P = 0.043*), medial crest coronal tangential angle (r = 0.307, P = 0.006*), olecranon fossa volume (r = -0.408, P < 0.001*), olecranon fossa surface area (r = -0.345, P = 0.002*) and coronoid fossa surface area (r = -0.279, P = 0.012*) were significantly correlated with the age of the subjects. In the comparison of people from different regions, the capitellum height, lateral trochlear high, trochlear groove high, trochlear depth and medial trochlear high of the Western population were 23.25 ± 2.56 m, 21.6 ± 2.20 mm, 17.8 ± 2.00 mm, 17.80 ± 2.00 mm, 29.9 ± 4.10 mm, are significantly higher than those in the Chinese population. while capitellum width (15.55 ± 2.68 mm) and capitellum depth (9.00 ± 1.00 mm) were slightly lower.ConclusionThe findings provide a basis for the design of distal humeral orthopaedic implants, ensuring greater alignment with the anatomical structure of the distal humerus and improved surgical outcomes. Furthermore, the study provides a reference point for the diagnosis and classification of distal humeral diseases, as well as guidance for patient rehabilitation.

Osteogenic citric acid linked chitosan coating of 3D-printed PLA scaffolds for preventing implant-associated infections

>25 % of the patients who receive orthopedic implants have been reported with implant-associated osteomyelitis, which can result in inflammation, osteolysis, and aseptic loosening of implants. Current treatment methods doesn't ensure defect healing and prevention from reinfection. Thermoplastic-based 3D-printed scaffolds offer a bioresorbable, biocompatible, and mechanical strong implant system. However, the hydrophobicity and bio-inertness of these polymers prevent their use in clinics. In this study, we developed dual functionalized scaffolds with osteogenic and antibacterial properties by immobilizing citric acid-linked chitosan on oxygen plasma etched 3D-printed PLA scaffolds through an EDC-NHS coupling reaction. Acellular mineralization of these scaffolds in DMEM demonstrated the deposition of crystalline hydroxyapatite. In addition, the antibacterial properties of these surface-modified scaffolds have been determined against E. coli and S. aureus, where the citric-linked chitosan biofunctionalized 3D-printed PLA scaffolds showed significantly higher antibacterial activity in comparison to oxygen-etched PLA and PLA scaffolds due to the synergistic effect of citric acid and chitosan functionalities. MG-63 cells exhibited increased proliferation and osteogenic activity on the modified scaffolds compared to the PLA and OP-PLA. These 3D-printed scaffolds, coated with citric-linked chitosan, can be a potential solution to orthopedic complications such as critical-sized bone defects and implant-associated osteomyelitis.

Investigation of the microstructural characteristics of laser-cladded Ti6Al4V titanium alloy and its corrosion behavior in simulated body fluid

Laser cladding technology has a wide range of potential industrial applications in the surface strengthening, repair and reuse of orthopedic implants. By employing this technique to conduct same-material surface restoration and enhancement on titanium alloys, it demonstrates significant developmental potential. However, the microstructure of laser additively manufactured titanium alloy differs significantly from that of traditional titanium alloys, which affects its corrosion resistance in human body fluids. To compare the corrosion resistance differences between the cladding layer and the substrate, this study investigates the microstructure of multi-pass laser cladding Ti6Al4V (TC4) titanium alloy and analyzes the corrosion morphology and corrosion products of the cladding layer in simulated body fluids (SBF). By comparing the electrochemical corrosion behavior of laser cladding with that of traditionally manufactured TC4, this research reveals the differences in corrosion resistance between the two titanium alloys. The research demonstrates that the microstructure of cladding primarily consists of prior-β grains and continuous grain boundary α phase, along with a complex basketweave structure composed of fine acicular α phase and lamellar α phase. Additionally, due to the complex thermal cycling process, the acicular α' colonies within the prior-β grains. These features enhance the cladding layer’s resistance to plastic deformation and increase microhardness, though with some uneven distribution. Interestingly, the TC4 cladding layer forms a porous passivation layer after corrosion, primarily composed of a TiO2 passivation film and deposits of hydroxyapatite and other phosphates. Due to the lower β-phase content, finer grains with higher energy states, and a greater proportion of high-angle grain boundaries (HAGBs) in the cladding layer, it exhibits higher electrochemical activity. As a result of these microstructural differences, the corrosion resistance of the TC4 cladding layer in SBF is inferior to that of TC4 manufactured using traditional techniques.

Statistical models and implant customization in hip arthroplasty: Seeking patient satisfaction through design

ObjectivesThis study conducts a systematic literature review to explore the role of statistical models and methods in the design of orthopedic implants, with a specific focus on hip arthroplasty. Through a comprehensive analysis of the scientific literature, it aims to understand the relevance and applicability of these models in implant development and research trends in the field of design. MethodsData analysis and co-occurrence mapping techniques were employed to investigate the statistical models used as predictors of satisfaction in hip arthroplasty and in implant design. This approach facilitated a detailed and objective assessment of existing literature, revealing key trends and identifying gaps in current knowledge. Key findingsThe review's findings underscore a burgeoning interest in implant customization, with a significant emphasis on leveraging statistical techniques for optimal design. The logistic model methodology was applied to analyze a survey of hip surgery specialists, revealing that the physician's age does not influence the decision to use a customized implant. Furthermore, the review highlighted a knowledge gap at the intersection of statistics and design discipline concerning implant customization. SignificanceDespite the recognized importance of customization in implant design, there remains a dearth of contributions from the design discipline perspective in the existing literature, indicating substantial room for improvement and the need for interdisciplinary integration. ConclusionThe integration of statistical methods in implant design is crucial, emphasizing the need for multidisciplinary approaches and customization to enhance patient satisfaction. This study provides a foundation for future research that could transform the field of hip arthroplasty through more personalized and effective solutions.

Advances in titanium alloys and orthopedic implants: new titanium alloys and future research directions

Advances in titanium alloys and orthopedic implants: new titanium alloys and future research directions

Innovative pH-triggered antibacterial nanofibrous coatings for enhanced metallic implant properties

Metallic stainless steel bone implants are widely used due to their excellent mechanical properties, low cost, and ease of fabrication. Nanofibrous composite polymers have been proposed as coatings to promote biocompatibility and osseointegration, thanks to their biomimetic morphology that resembles the extracellular matrix. However, critical practical issues are often overlooked in the literature. For instance, applying coatings to implants with different shapes presents a significant technological challenge, as does evaluating viable sterilization procedures for hybrid devices containing electrospun polymers. In addition, infections pose a risk in any surgical procedure and can lead to implant failure, there is a need for antimicrobial prevention during surgery as well as in the short term afterward. In this work, we propose a new and straightforward method for manufacturing nanofibrous composite coatings directly on thin cylindrical-shaped metallic implants. Poly(ε-caprolactone) (PCL) nanofibers containing bioactive glass microparticles were electrospun onto stainless steel wires and then post-treated using two different strategies to achieve both hydrophilicity and surface disinfection. To address antimicrobial properties, amoxicillin-loaded Eudragit®E nanofibers were co-electrospun to impart pH-selective release behavior in event of a potential infection. The resulting composite hybrid coatings were characterized morphologically, physically, chemically, and electrochemically. The antibacterial behavior was evaluated at different media, confirming the release of the antibiotic in the pH range where infection is likely to occur. The impact of this study lies in its potential to significantly enhance the safety and efficacy of orthopedic implants by offering a novel, adaptable solution to combat infection. By integrating a pH-responsive drug delivery system with antimicrobial coatings, this approach not only provides a preventive measure during and after surgery but also addresses the growing issue of antibiotic resistance by targeting specific infection conditions.

Investigation of Coupling Effect for Adjacent Orthopedic Implants on MRI Radio-Frequency Heating

This paper investigates the mechanism of radio-frequency (RF) heating that occurs when two adjacent orthopedic implants are present together under magnetic resonance imaging (MRI) at 1.5 Tesla and 3.0 Tesla. When a patient has multiple implants close to each other, interactions between the implants may increase RF heating. Typical generic interlocking plate and antibiotic nail implants are adopted as examples. To analyze the effect of adjacent implants, the amplitude and direction of incident and scattering vector electric fields at the hot spot position are calculated and extracted using numerical simulation based on Huygens principle. It is shown that a strong coupling effect occurs due to the existence of both the incident field and a strong scattering field. Huygens principle can be used to obtain the first and second order scattering fields generated between implants. If the first- and second-order electric field terms are summed within a certain region, the RF-induced heating of this dual-implant system increases.

Tribological Behavior of 316L Stainless Steel Fabricated Using Metal Extrusion Additive Manufacturing Under Dry and Simulated Body Fluid‐Lubricated Conditions

Herein, the tribological behavior of 316L stainless steel (SS) fabricated using metal extrusion additive manufacturing (MEAM) is investigated both under dry and simulated body fluid (SBF)‐lubricated conditions. The results and mechanisms are compared with those of 316L SS fabricated via selective laser melting (SLM) and hot rolling (HR). Under dry‐friction conditions, the 316L SS fabricated via MEAM shows inferior tribological performance compared with those fabricated via SLM and HR, primarily because of its lower initial hardness and better plasticity, which increase both abrasive and adhesive wear. Under SBF‐lubricated conditions, the tribological performance of the 316L SS fabricated via MEAM is comparable to that fabricated via HR and superior to that fabricated via SLM. The wear rate of the MEAM‐fabricated 316L SS is 16.8% and 3.2% lower than SLM‐ and HR‐fabricated, respectively. The numerous pores on 316L SS serve as traps for wear particles, which contribute to the reduction of three‐body wear. In terms of wear under SBF‐lubricated conditions, MEAM technology appears to be a promising method for the fabrication of customized 316L orthopedic implants.

Degradation Kinetics of As-Cast and Solution-Treated (T4) Magnesium-Based Alloys for Biodegradable Orthopedic Implants

Degradation Kinetics of As-Cast and Solution-Treated (T4) Magnesium-Based Alloys for Biodegradable Orthopedic Implants

Carbon-carbon composite material as a potential basis for orthopedic implants

Aim. To determine the cytocompatibility of carbon-carbon composite materials (CCCM) and assess their ability to be impregnated with vancomycin.Materials and Methods. The study included samples of carbon-carbon composite materials (CCCM). The cytocompatibility of CCCM blocks was evaluated using a culture of eukaryotic cells (Vero cell line). Biofilms of S. aureus ATCC 29213 (MSSA), S. aureus ATCC 43300 (MRSA), S. epidermidis ATCC 12228 (MSSE), and S. epidermidis ATCC 29887 (MRSE) were formed by immersing sterile test samples of CCCM into a nutrient medium which contained bacteria. After 24-hour incubation, the samples were washed, placed in an ultrasonic bath, and sonication fluid was inoculated using the sector method. To saturate the CCCM blocks with antibiotics, they were placed into a vancomycin solution and then lyophilized under negative pressure with gradual heating. The antimicrobial activity of the resulting blocks was studied using the cup plate method against the same reference cultures of staphylococci. The dynamics of vancomycin elution from CCCM was investigated using high-performance liquid chromatography.Results. Vero cells maintained their viability in the presence of the tested material. Considering the highly porous structure of CCCM and variable diameter of the pores, we suggested a good osteointegration potential of this material. On the samples without an impregnation with an antibacterial drug, reference strains of staphylococci were able to form a biofilm with a sufficient number of bacterial cells to initiate an infectious process. The duration of antimicrobial activity of the antibioticim-pregnated samples against the reference staphylococcal strains was up to 3 days. The majority of the antibiotic eluted from the CCCM into the incubation medium during the first two days.Conclusion. The cytocompatibility and porosity of CCCM in combination with a vancomycin impregnation makes this material promising for the fabrication of implants with antimicrobial activity as well as tissue engineering constructs.

Developing novel Ti-Nb-Zr-Mo-Sn-O biomedical titanium alloys with high strength and low modulus through high-throughput experiments

Biomedical titanium alloys have been widely used as surgical implant materials, but traditional biomedical titanium alloys no longer meet practical needs, and there is an urgent need to develop new biomedical titanium alloys. In this study, the composition, microstructure, and mechanical properties of novel Ti-xNb-yZr-5Mo-6Sn-0.6O biomedical titanium alloys were investigated based on diffusion multiple high-throughput experiments. The results showed that although the microstructure of the alloys transitioned from β + α″ to β phase with the increase of Nb and Zr content, the β-stabilizing effect of Zr is weaker. The microhardness and elastic modulus of the alloys varied in the range of 2.7∼7.8GPa and 74.3∼130.2GPa, and depended strongly on the Nb content. In the Ti-xNb-yZr-5Mo-6Sn-0.6O system alloy, the Ti-7.8Nb-1.7Zr-5Mo-6Sn-0.6O alloy with the high hardness of 5.5 GPa and low elastic modulus of 74.3 GPa is a promising candidate for orthopedic implants. Moreover, this work indicates that high-throughput experiments are an effective method for rapidly developing high-performance biomedical titanium alloys.

Synthesis of composite coatings based on Mg and Ti oxides by PEO for modulation of Mg corrosion resistance

In this study, the application of Plasma Electrolytic Oxidation (PEO) technique was investigated for fabricating composite coatings on magnesium (Mg) substrates aimed at modulating their corrosion resistance, an important characteristic for biodegradable orthopedic implants. The coatings were manufactured using an electrolytic solution containing MgO and TiO2 oxides, varying mass ratios, at currents of 30 mA and 200 mA. X-ray diffraction patterns confirmed the presence of TiO2 and MgO phases in the coatings, demonstrating the PEO capability to modulate the chemical composition by adjusting the mass ratio of oxides in the electrolytic solution. Microstructural analysis revealed decreased surface roughness with increasing TiO2 concentration. Corrosion tests indicated a significant improvement in corrosion resistance for all coatings compared to uncoated Mg substrate. In particularly, coatings with higher TiO2 concentrations, and those applied at a current density of 30 mA exhibited, enhanced corrosion resistance.

Enhanced osteointegration and osteogenesis of osteoblast cells by laser-induced surface modification of Ti implants

Dental and orthopedic implants have become routine medical technologies for tooth replacement and bone fixation. Despite significant progress in implantology, achieving sufficient osseointegration remains a challenge, often leading to implant failure over the long term. Nanotechnology offers the potential to mimic the natural patterns of living tissues, providing a promising platform for tissue engineering and implant surface design. Among the various methods for developing nanostructures, High-Regular Laser-Induced Periodic Surface Structures (HR-LIPSS) techniques stand out for their ability to fabricate highly ordered nanostructures with excellent long-range repeatability and production efficiency. In this study, we utilized an innovative technical approach to generate traditional laser-induced superficial LIPSS nanostructures, followed by detailed surface analysis using classical microscopy and physicochemical methods. Our findings demonstrate for the first time that nanostructured LIPSS surfaces can significantly enhance cell adhesion and proliferation while providing an optimal environment for cell metabolism. Given the high reproducibility, low cost, and potential of HR-LIPSS techniques to support cell growth and differentiation, this novel technology has the potential to impact both the industrial development of new implants and clinical outcomes after implantation.

In Vitro Proliferation of MG-63 Cells in Additively Manufactured Ti-6Al-4V Biomimetic Lattice Structures with Varying Strut Geometry and Porosity.

Lattice structures have demonstrated the ability to provide secondary stability in orthopedic implants by promoting internal bone growth. In response to the growing prevalence of lattices in orthopedic design, we investigated the effects of porosity and unit cell geometry in additively manufactured Ti-6Al-4V biomimetic lattice structures on the osteogenesis of human MG-63 osteoblastic cell lines in vitro. We analyzed glucose consumption, alkaline phosphatase (ALP) concentration, and end-of-culture cell count as markers for osteogenic growth. Two different strut geometries were utilized (cubic and body-centered cubic), along with four different pore sizes (400, 500, 600, and 900 µm, representing 40-90% porosity in a 10 mm cube), in addition to a solid specimen. Structural characterization was performed using scanning electron microscopy. The results indicated that lattices with a 900 µm pore size exhibited the highest glucose consumption, the greatest change in ALP activity, and the highest cell count when compared to other pore sizes. Cubic 900 µm lattice structures outperformed other specimens in facilitating the maturation of viable MG-63 cells from the formation to the mineralization phase of bone remodeling, offering the most promise for osseointegration in additively manufactured titanium implants in the future. However, irrespective of a particular pore size or unit cell geometry, it was found that all the lattices were capable of promoting osteogenic growth due to surface roughness in the printed parts.

Designs and mechanical responses of 3D-printed Ti6Al4V porous structures based on triply periodic minimal surfaces with different iso-values

With the increasing applications of additive manufacturing in orthopaedic implants and numerous designs of porous structures available, there is a strong need and opportunity to optimize the structure designs for improved bone integration. Here we created a unique group of sheet structures based on triply periodic minimal surface (TPMS) by varying the iso-value and systematically examined how iso-value influences the mechanical performance of sheet diamond TPMS structures compared to the Octet truss structure. Four iso-values (C) 0, 0.25, 0.5, and 0.75 were designed for sheet Diamond (OSD) TPMS with varying porosity, and Ti6Al4V powder bed fusion was used to produce the porous structures. Compressive tests revealed that iso-value C significantly affected mechanical performance, and interestingly, the impact was porosity-dependent. At high relative density (>0.25), OSD0 (C = 0) displayed the highest elastic modulus and yield strength, whereas at low relative density (<0.25), OSD0.5 showed the highest among all OSD structures. Regarding failure mechanisms, OSD0, OSD0.25, and OSD0.75 showed a mixed domination of stretching and bending, while OSD0.5 was predominantly stretching-dominated. Finite Element Analysis (FEA) found that local yielding initiated at cell nodes upon loading, followed by surface bending and the formation of single or multiple shear bands near the cell nodes. This work demonstrated the feasibility of improving the mechanical performance of porous TPMS structures by simple adjustments in their governing trigonometric functions, serving as a starting point to customize porous structures for specific applications.

A Technique for Retrieval of Screw for Missed Screw Head

Abstract Background: Orthopaedic implants are medical devices used to replace or fix bones or to replace the articulating surfaces of joints. Once fracture healing is complete, these implants may no longer serve a functional purpose and can be removed. During implant removal surgeries, surgeons may encounter various challenges, such as stripped screw heads. While several methods for addressing this issue have been previously described, this study introduces a novel technique for retrieving stripped screw heads. Methods: Between May 2021 and September 2023, 21 patients underwent implant removal surgeries where stripped screw heads were encountered intraoperatively. The technique involved cutting the screw head with a metal-cutting drill bit, which proved to be effective in facilitating retrieval. Results: All the screws with stripped screw head could be extracted using our technique. Conclusion: Compared to traditional methods, this new approach requires less specialized skill and equipment and is more cost-effective.

A Surface-Mediated Biomimetic Porous Polyether-Ether-Ketone Scaffold for Regulating Immunity and Promoting Osteogenesis.

The repair of critical-sized bone defects remains a major challenge for clinical orthopedic surgery. Here, we develop a surface biofunctionalized three-dimensional (3D) porous polyether-ether-ketone (PEEK) scaffold that can simultaneously promote osteogenesis and regulate macrophage polarization. The scaffold is created using polydopamine (PDA)-assisted immobilization of silk fibroin (SF) and the electrostatic self-assembly of nanocrystalline hydroxyapatite (nano-HA) on a 3D-printed porous PEEK scaffold. The SF/nano-HA functionalized surface provides a bone-like microenvironment for osteoblastic cells' adhesion, proliferation, mineralization and osteogenic differentiation. Moreover, the biofunctionalized surface can effectively drive macrophages polarization from the pro-inflammatory M1 phenotype to the anti-inflammatory M2 phenotype. Integrin β1-specific cell-matrix binding and the activation of Ca2+ receptor-mediated signaling pathway play critical roles in the regulation of macrophage polarization. Compared with the as-printed scaffold, the SF/nano-HA functionalized porous PEEK scaffold induces minimal inflammatory response, enhanced angiogenesis, and substantial new bone formation, resulting in improved osseointegration in vivo. This study not only develops a promising candidate for bone repair but also demonstrates a facile surface biofunctionalization strategy for orthopedic implants to improve osseointegration by stimulating osteogenesis and regulating immunity.

3D-printed porous titanium rods equipped with vancomycin-loaded hydrogels and polycaprolactone membranes for intelligent antibacterial drug release

Implant-related infections pose significant challenges to orthopedic surgeries due to the high risk of severe complications. The widespread use of bioactive prostheses in joint replacements, featuring roughened surfaces and tight integration with the bone marrow cavity, has facilitated bacterial proliferation and complicated treatment. Developing antibacterial coatings for orthopedic implants has been a key research focus in recent years to address this critical issue. Researchers have designed coatings using various materials and antibacterial strategies. In this study, we fabricated 3D-printed porous titanium rods, incorporated vancomycin-loaded mPEG750-b-PCL2500 gel, and coated them with a PCL layer. We then evaluated the antibacterial efficacy through both in vitro and in vivo experiments. Our coating passively inhibits bacterial biofilm formation and actively controls antibiotic release in response to bacterial growth, providing a practical solution for proactive and sustained infection control. This study utilized 3D printing technology to produce porous titanium rod implants simulating bioactive joint prostheses. The porous structure of the titanium rods was used to load a thermoresponsive gel, mPEG750-b-PCL2500 (PEG: polyethylene glycol; PCL: polycaprolactone), serving as a novel drug delivery system carrying vancomycin for controlled antibiotic release. The assembly was then covered with a PCL membrane that inhibits bacterial biofilm formation early in infection and degrades when exposed to lipase solutions, mimicking enzymatic activity during bacterial infections. This setup provides infection-responsive protection and promotes drug release. We investigated the coating’s controlled release, antibacterial capability, and biocompatibility through in vitro experiments. We established a Staphylococcus aureus infection model in rabbits, implanting titanium rods in the femoral medullary cavity. We evaluated the efficacy and safety of the composite coating in preventing implant-related infections using imaging, hematology, and pathology. In vitro experiments demonstrated that the PCL membrane stably protects encapsulated vancomycin during PBS immersion. The PCL membrane rapidly degraded at a lipase concentration of 0.2 mg/mL. The mPEG750-b-PCL2500 gel ensured stable and sustained vancomycin release, inhibiting bacterial growth. We investigated the antibacterial effect of the 3D-printed titanium material, coated with PCL and loaded with mPEG750-b-PCL2500 hydrogel, using a rabbit Staphylococcus aureus infection model. Imaging, hematology, and histopathology confirmed that our composite antibacterial coating exhibited excellent antibacterial effects and infection prevention, with good safety in trials. Our results indicate that the composite antibacterial coating effectively protects vancomycin in the hydrogel from premature release in the absence of bacterial infection. The outer PCL membrane inhibits bacterial growth and prevents biofilm formation. Upon contact with bacterial lipase, the PCL membrane rapidly degrades, releasing vancomycin for antibacterial action. The mPEG750-b-PCL2500 gel provides stable and sustained vancomycin release, prolonging its antibacterial effects. Our composite antibacterial coating demonstrates promising potential for clinical application.

A biomimetic chiral auxetic vertebral meta-shell

Abstract The work presents a novel thin-walled biomimetic auxetic meta-shell for patient-specific vertebral orthopedic implants. The proposed design stemmed from the concept of an intrinsically multiple curved auxetic meta-structure, which is created by folding a 2D bio-inspired chiral geometry according to the morphology of human vertebral cortical bones. Through a multi-view stereo Digital Image Correlation (DIC) system, we investigated the mechanical response of a bio-grade titanium (Ti6Al4V ELI) additively manufactured prototype of the meta-structure under compressive loadings. In addition, we analyzed the morphology of the prototype using a scanning electron microscopy (SEM) and an optical image dimension measurement system both before and after compressive tests. An accurate Finite Element model, which exactly reproduced the geometry of the 3D printed meta-shell, was implemented and calibrated against experimental results, obtaining a precise prediction tool of its mechanical response. The findings of this work demonstrate that the designed meta-shell shows a peculiar auxetic behavior, a targeted stiffness matching to that of human vertebral bone tissues and a higher global elastic strain capability compared to those of monolithic traditional vertebral body replacements.&amp;#xD;&amp;#xD;