Porous construction and surface modification of titanium-based materials for osteogenesis: A review

Effect of Ti6Al4V Alloy Surface and Porosity on Bone Osseointegration: In Vivo Pilot Study in Rabbits

Unmodified Ti6Al4V can osseointegrate, but sometimes this capacity needs to be improved. This study aimed to see how much porosity improves osseointegration in a Ti6Al4V implant. Three types of Ti6Al4V cylindrical-shaped implants (13.00 mm length × 5.00 mm diameter) were evaluated: solid sandblasted acid-etched, sintered, and porous 3D-printed (681.00 µm average pore size). Fifteen 20-week-old nullipara female parasite-free New Zealand California white rabbits were used, employing the femoral condyle defect model and undertaking µ-CT analysis and pull-out testing eight weeks later. On µ-CT densitometric analysis, the solid sandblasted rod showed the highest new bone growth around the implant. Bone growth was higher inside the implants for the porous 3D-printed (54.00 ± 5.00 mm3) than for the sintered (1.00 ± 0.05 mm3) and zero for the sandblasted implants. In the pull-out test, there were no statistically significant differences in the ANOVA analysis between the sintered (900.00 N ± 310.00 N) and porous 3D-printed (700.00 N ± 220.00 N) implants. Such differences did exist between the sandblasted material (220.00 N ± 50.00 N) and the two other materials (sintered p 0.002, porous p 0.034). The porous 3D-printed and sintered implant pull-out strength were significantly better than that of the solid rod sandblasted implant. Still, there were no statistically significant differences between the first two.

Clinical Application of 3D-Printed Custom Hemipelvic Prostheses With Negative Poisson's Ratio Porous Structures in Reconstruction After Resection of Pelvic Malignant Tumors

OBJECTIVES

Pelvic bone tumor resection and reconstruction present significant challenges due to complex anatomy and weight-bearing demands. 3D-printed hemipelvic prostheses, incorporating customized osteotomy guides and porous structures, offer a promising solution for enhancing osseointegration. This study evaluates the long-term outcomes of 3D-printed custom hemipelvic reconstruction with a focus on the integration of auxetic biomaterials with a negative Poisson's ratio to optimize mechanical properties.

METHODS

A retrospective analysis was conducted on 12 patients with primary pelvic malignancies who underwent reconstruction using 3D-printed hemipelvic prostheses between January 2018 and May 2023. Follow-up duration was 48 months (range, 29-64 months) Oncological, functional, surgical, pain control, and radiographic outcomes were assessed.

RESULTS

At the latest follow-up, 8 patients (66.7%) were disease-free, 3 (25%) had disease progression, and 1 (8.3%) died from metastatic complications. Functional outcomes improved significantly, with the MSTS-93 score increasing from 15 (range, 12-17) to 26 (range, 21-29). Pain scores decreased from 5 (range, 4-7) to 1 (range, 0-2). The median surgical duration was 270 min (range, 150-560 min), with intraoperative blood loss averaging 3200 mL (range, 1900-6300 mL). Complications included poor wound healing in 2 patients (16.7%), managed with VAC drainage. No mechanical failures, loosening, or fractures occurred. Accurate osteotomy, prosthesis implantation, and screw fixation were achieved. Successful osseointegration was observed in all cases, with no signs of bone absorption or osteolysis.

CONCLUSIONS

3D-printed custom hemipelvic prostheses with auxetic biomaterials offer an effective solution for pelvic reconstruction, providing promising oncological, functional, and radiographic outcomes. These findings support the use of 3D printing in complex pelvic defect reconstruction, optimizing both osteointegration and mechanical strength.

Biomechanical analysis of triply periodic minimal surfaces-based porous dental implants versus solid implants: impact of peri-implant bone density on micromotion

Dental implants restore facial appearance and improve chewing and speaking abilities in edentulous patients. However, solid implants often cause stress shielding, peri-implantitis, and poor bone integration due to low osteointegration, leading to failure. To address this, three porous implants-Gyroid, Schwarz Diamond (DI), and Schwarz Primitive-were designed and evaluated using Finite Element Analysis (FEA) and Computational Fluid Dynamics (CFD). FEA confirmed mechanical stability, with DI reducing bone stress but increasing micromotion in lower-density bone. Experimental and computational testing showed FEA slightly overpredicted stress, while CFD confirmed DI's permeability closely matches cancellous bone.

Effect of Bulk Phase Composition on the Growth of PEO Coatings on the Biomedical Ti-6Al-4V Alloy

This study investigated the effects of plasma electrolytic oxidation (PEO) treatment in a Ca- and P-rich electrolyte on the surface of the Ti-6Al-4V alloy with distinct α/β phase proportions previously induced by heat treatments. The results revealed that the α/β phase proportions were successfully altered by the heat treatment temperatures, forming α phase plates surrounded by β phase precipitates. PEO-treated samples exhibited a thick and microsized porous TiO2 coating in the anatase and rutile crystalline forms. The oxide layer was depleted by Al and V atoms, while Ca and P were gradually enriched along the coatings. Chemical analysis also indicated the absorption of water and organic molecules into the outer layer. PEO-treated samples had microscale roughness and thickness, hydrophilic behavior, and surface energy mainly formed by the dispersive component. The bulk's elastic modulus decreased with β phase precipitation, while the alloying elements directly influenced the Vickers microhardness. The corrosion tests indicated a stable and protective layer in the PEO-treated samples, showing better corrosion resistance than untreated ones. Overall, the findings indicated that the α and β phase proportion significantly impacts the mechanical properties, while the PEO treatment acts in the corrosion protection and surface aspects, suggesting that combining both approaches could be a powerful tool in biomedical applications.

Patient-Specific 3-Dimensional-Printed Orthopedic Implants and Surgical Devices Are Potential Alternatives to Conventional Technology But Require Additional Characterization

Background

Three-dimensional (3D) printing allows anatomical models, guides, and implants to be easily customized to individual patients. Three-dimensional-printed devices can be used for a number of purposes in the medical field, yet there is a lack of data on the implementation of 3D-printed patient-specific implants and surgical guides in orthopedics. The objective of this review of the literature was to summarize the implementation of 3D printing in orthopedic surgery and identify areas that require more investigation.

Methods

PubMed and Scopus were used to perform a literature search. Articles that described 3D-printed patient-specific orthopedic implants or intraoperative guides were reviewed. Relevant articles were compiled and summarized to determine the role of personalized 3D-printed implants in orthopedic surgery.

Results

A total of 58 papers were selected. Overall, 3D-printed implants and surgical guides were shown to be effective in the selected cases. Patients with bone tumors benefitted from custom 3D-printed implants, which allow aggressive resection while preserving the function and mechanical stability of the limb. Eighty-one percent of devices were made using titanium, and 48% of articles reported the use of 3D printing in oncology. Some reported adverse events including wound dehiscence, periprosthetic infection, dislocation, and sequelae of malignancy. Regulations surrounding the use of 3D-printed surgical devices are ambiguous.

Conclusions

Three-dimensional-printed orthopedic implants and guides present an alternative to commercial devices, as they allow for customizability that is useful in cases of anatomic complexity. A variety of materials were surveyed across multiple subspecialties. Large controlled studies are necessary to compare patient-specific implants with the standard of care and evaluate their safety profiles over time.

Design of internal fixation implants for fracture: A review

Internal fixation is the most common and effective fracture treatment, and the design of Internal Fixation Implants (IFI) is important for fracture healing. In recent decades, IFI have been designed from the aspects of materials, geometry, fixation methods and functional characteristics. However, there has been no comprehensive summary on the evaluation method and design methods of IFI. This paper aims to review and analyze the key issues involved in the design of IFI, to provide references for IFI design. Firstly, the main factors affecting the healing effect are summarized and the design requirements of IFI are put forward through the analysis of fracture healing process. Secondly, the evaluation methods of IFI are compared and summarized, and the importance of evaluation methods based on fracture healing theory is emphasized. Subsequently, the properties and application scopes of common biomaterials for IFI are introduced. And the IFI, which is used widely, such as bone plate, intramedullary nail and embracing device, are summed up from the aspects of design factors and design methods. Highlight the distinctive contributions of additive manufacturing for the fabrication of implants and surface treatment for improving the multifunctionality of implants. Finally, the design concept of ideal IFI and the potential research content in the future are proposed based on the design requirements and the summary of the existing design studies.

The translational potential of this article

This study summarizes and analyzes the key issues involved in the design of IFI, which provide references for IFI design. A discussion on future research directions and suggestion were made, which is expected to advance the research in this field.

Microplasma-Sprayed Titanium and Hydroxyapatite Coatings on Ti6Al4V Alloy: in vitro Biocompatibility and Corrosion Resistance: Part I

This two-part paper investigates the bioactivity and mechanical properties of coatings applied to Ti6Al4V, a common titanium alloy used in endoprosthetic implants. Coatings made from hydroxyapatite (HA) powder and commercially pure titanium (CP-Ti) wires were applied using microplasma spraying. The study focuses on the responses of rat mesenchymal stem cells (MSCs), which are essential for bone healing, to these coatings. Part I shows how adjusting the microplasma spraying process allows coatings with varying porosity and surface roughness to be achieved.

External Stimuli-Responsive Strategies for Surface Modification of Orthopedic Implants: Killing Bacteria and Enhancing Osteogenesis

Bacterial infection and insufficient osteogenic activity are the main causes of orthopedic implant failure. Conventional surface modification methods are difficult to meet the requirements for long-term implant placement. In order to better regulate the function of implant surfaces, especially to improve both the antibacterial and osteogenic activity, external stimuli-responsive (ESR) strategies have been employed for the surface modification of orthopedic implants. External stimuli act as "smart switches" to regulate the surface interactions with bacteria and cells. The balance between antibacterial and osteogenic capabilities of implant surfaces can be achieved through these specific ESR manifestations, including temperature changes, reactive oxygen species production, controlled release of bioactive molecules, controlled release of functional ions, etc. This Review summarizes the recent progress on different ESR strategies (based on light, ultrasound, electric, and magnetic fields) that can effectively balance antibacterial performance and osteogenic capability of orthopedic implants. Furthermore, the current limitations and challenges of ESR strategies for surface modification of orthopedic implants as well as future development direction are also discussed.

Antimicrobial peptide GL13K-Modified titanium in the epigenetic regulation of osteoclast differentiation via H3K27me3

Implant surface designs have advanced to address challenges in oral rehabilitation for healthy and compromised bone. Several studies have analyzed the effects of altering material surfaces on osteogenic differentiation. However, the crucial role of osteoclasts in osseointegration has often been overlooked. Overactive osteoclasts can compromise implant stability. In this study, we employed a silanization method to alter pure titanium to produce a surface loaded with the antimicrobial peptide GL13K that enhanced biocompatibility. Pure titanium (Ti), silanization-modified titanium, and GL13K-modified titanium (GL13K-Ti) were co-cultured with macrophages. Our findings indicated that GL13K-Ti partially inhibited osteoclastogenesis and expression of osteoclast-related genes and proteins by limiting the formation of the actin ring, an important structure for osteoclast bone resorption. Our subsequent experiments confirmed the epigenetic role in regulating this process. GL13K-Ti was found to impact the degree of methylation modifications of H3K27 in the NFATc1 promoter region following RANKL-induced osteoclastic differentiation. In conclusion, our study unveils the potential mechanism of methylation modifications, a type of epigenetic regulatory modality, on osteoclastogenesis and activity on the surface of a material. This presents novel concepts and ideas for further broadening the clinical indications of oral implants and targeting the design of implant surfaces.

Harnessing 3D printed highly porous Ti-6Al-4V scaffolds coated with graphene oxide to promote osteogenesis

Bone tissue engineering (BTE) strategies have been developed to address challenges in orthopedic and dental therapy by expediting osseointegration and new bone formation. In this study, we developed irregular porous Ti-6Al-4V scaffolds coated with reduced graphene oxide (rGO), specifically rGO-pTi, and investigated their ability to stimulate osseointegration in vivo. The rGO-pTi scaffolds exhibited unique irregular micropores and high hydrophilicity, facilitating protein adsorption and cell growth. In vitro assays revealed that the rGO-pTi scaffolds increased alkaline phosphatase (ALP) activity, mineralization nodule formation, and osteogenic gene upregulation in MC3T3-E1 preosteoblasts. Moreover, in vivo transplantation of rGO-pTi scaffolds in rabbit calvarial bone defects showed improved bone matrix formation and osseointegration without hemorrhage. These findings highlight the potential of combining rGO with irregular micropores as a promising BTE scaffold for bone regeneration.

In Vivo Assessment of a Triple Periodic Minimal Surface Based Biomimmetic Gyroid as an Implant Material in a Rabbit Tibia Model

Biomimetic approaches to implant construction are a rising frontier in implantology. Triple Periodic Minimal Surface (TPMS)-based additively manufactured gyroid structures offer a mean curvature of zero, rendering this structure an ideal porous architecture. Previous studies have demonstrated the ability of these structures to effectively mimic the mechanical cues required for optimal implant construction. The porous nature of gyroid materials enhances bone ingrowth, thereby improving implant stability within the body. This enhancement is attributed to the increased surface area of the gyroid structure, which is approximately 185% higher than that of a dense material of the same form factor. This larger surface area allows for enhanced cellular attachment and nutrient circulation facilitated by the porous channels. This study aims to evaluate the biological performance of a gyroid-based Ti6Al-4V implant material compared to a dense alloy counterpart. Cellular viability was assessed using the lactate dehydrogenase (LDH) assay, which demonstrated that the gyroid surface allowed marginally higher viability than dense material. The in vivo integration was studied over 6 weeks using a rabbit tibia model and characterized using X-ray, micro-CT, and histopathological examination. With a metal volume of 8.1%, the gyroid exhibited a bone volume/total volume (BV/TV) ratio of 9.6%, which is 11-fold higher than that of dense metal (0.8%). Histological assessments revealed neovascularization, in-bone growth, and the presence of a Haversian system in the gyroid structure, hinting at superior osteointegration.

A preliminary study of the mechanical properties of 3D-printed personalized mesh titanium alloy prostheses and repair of hemi-mandibular defect in dogs

This study is a preliminary investigation exploring the mechanical properties of three-dimensional (3D)-printed personalized mesh titanium alloy prostheses and the feasibility of repairing hemi-mandibular defects. The ANSYS 14.0 software and selective laser melting (SLM) were used to produce personalized mesh titanium alloy scaffolds. Scaffolds printed using different parameters underwent fatigue property tests and scanning electron microscopy (SEM) of the fracture points. Models of hemi-mandibular defects (encompassing the temporomandibular joint) were created using beagle dogs. Freeze-dried allogeneic mandibles or 3D-printed personalized mesh titanium alloy prostheses were used for repair. Gross observation, computed tomography (CT), SEM, and histological examinations were used to compare the two repair methods. The prostheses with filament diameters of 0.5 and 0.7 mm could withstand 14,000 times and >600,000 cycles of alternating stresses, respectively. The truss-structure scaffold with a large aperture and large aperture ratio could withstand roughly 250,000 cycles of alternating forces. The allogeneic mandible graft required intraoperative shaping, while the 3D-printed mesh titanium alloy prostheses were personalized and did not require intraoperative shaping. The articular disc on the non-operated sides experienced degenerative changes. No liver and kidney toxicity was observed in the two groups of animals. The 3D-printed mesh titanium alloy prostheses could effectively restore the shape of the mandibular defect region and reconstruct the temporomandibular joint.

A novel porous titanium with engineered surface for bone defect repair in load-bearing position

Porous titanium exhibits low elastic modulus and porous structure is thought to be a promising implant in bone defect repair. However, the bioinert and low mechanical strength of porous titanium have limited its clinical application, especially in load-bearing bone defect repair. Our previous study has reported an infiltration casting and acid corrosion (IC-AC) method to fabricate a novel porous titanium (pTi) with 40% porosity and 0.4 mm pore diameter, which exerts mechanical property matching with cortical bone and interconnected channels. In this study, we introduced a nanoporous coating and incorporated an osteogenic element strontium (Sr) on the surface of porous titanium (named as Sr-micro arch oxidation [MAO]) to improve the osteogenic ability of the pTi by MAO. Better biocompatibility of Sr-MAO was verified by cell adhesion experiment and cell counting kit-8 (CCK-8) test. The in vitro osteogenic-related tests such as immunofluorescence staining, alkaline phosphatase staining and real-time polymerase chain reaction (RT-PCR) demonstrated better osteogenic ability of Sr-MAO. Femoral bone defect repair model was employed to evaluate the osseointegration of samples in vivo. Results of micro-CT scanning, sequential fluorochrome labeling and Van Gieson staining suggested that Sr-MAO showed better in vivo osteogenic ability than other groups. Taking results of both in vitro and in vivo experiment together, this study indicated the Sr-MAO porous titanium could be a promising implant load-bearing bone defect.

Application and Perspectives: Magnesium Materials in Bone Regeneration

The field of bone regeneration has always been a hot and difficult research area, and there is no perfect strategy at present. As a new type of biodegradable material, magnesium alloys have excellent mechanical properties and bone promoting ability. Compared with other inert metals, magnesium alloys have significant advantages and broad application prospects in the field of bone regeneration. By searching the official Web sites and databases of various funds, this paper summarizes the research status of magnesium composites in the field of bone regeneration and introduces the latest scientific research achievements and clinical transformations of scholars in various countries and regions, such as improving the corrosion resistance of magnesium alloys by adding coatings. Finally, this paper points out the current problems and challenges, aiming to provide ideas and help for the development of new strategies for the treatment of bone defects and fractures.

Debulking of the Femoral Stem in a Primary Total Hip Joint Replacement: A Novel Method to Reduce Stress Shielding

In current-generation designs of total primary hip joint replacement, the prostheses are fabricated from alloys. The modulus of elasticity of the alloy is substantially higher than that of the surrounding bone. This discrepancy plays a role in a phenomenon known as stress shielding, in which the bone bears a reduced proportion of the applied load. Stress shielding has been implicated in aseptic loosening of the implant which, in turn, results in reduction in the in vivo life of the implant. Rigid implants shield surrounding bone from mechanical loading, and the reduction in skeletal stress necessary to maintain bone mass and density results in accelerated bone loss, the forerunner to implant loosening. Femoral stems of various geometries and surface modifications, materials and material distributions, and porous structures have been investigated to achieve mechanical properties of stems closer to those of bone to mitigate stress shielding. For improved load transfer from implant to femur, the proposed study investigated a strategic debulking effort to impart controlled flexibility while retaining sufficient strength and endurance properties. Using an iterative design process, debulked configurations based on an internal skeletal truss framework were evaluated using finite element analysis. The implant models analyzed were solid; hollow, with a proximal hollowed stem; FB-2A, with thin, curved trusses extending from the central spine; and FB-3B and FB-3C, with thick, flat trusses extending from the central spine in a balanced-truss and a hemi-truss configuration, respectively. As outlined in the International Organization for Standardization (ISO) 7206 standards, implants were offset in natural femur for evaluation of load distribution or potted in testing cylinders for fatigue testing. The commonality across all debulked designs was the minimization of proximal stress shielding compared to conventional solid implants. Stem topography can influence performance, and the truss implants with or without the calcar collar were evaluated. Load sharing was equally effective irrespective of the collar; however, the collar was critical to reducing the stresses in the implant. Whether bonded directly to bone or cemented in the femur, the truss stem was effective at limiting stress shielding. However, a localized increase in maximum principal stress at the proximal lateral junction could adversely affect cement integrity. The controlled accommodation of deformation of the implant wall contributes to the load sharing capability of the truss implant, and for a superior biomechanical performance, the collared stem should be implanted in interference fit. Considering the results of all implant designs, the truss implant model FB-3C was the best model.

Titanium Surfaces with a Laser-Produced Microchannel Structure Enhance Pre-Osteoblast Proliferation, Maturation, and Extracellular Mineralization In Vitro

The clinical success of dental titanium implants is profoundly linked to implant stability and osseointegration, which comprises pre-osteoblast proliferation, osteogenic differentiation, and extracellular mineralization. Because of the bio-inert nature of titanium, surface processing using subtractive or additive methods enhances osseointegration ability but limits the benefit due to accompanying surface contamination. By contrast, laser processing methods increase the roughness of the implant surface without contamination. However, the effects of laser-mediated distinct surface structures on the osteointegration level of osteoblasts are controversial. The role of a titanium surface with a laser-mediated microchannel structure in pre-osteoblast maturation remains unclear. This study aimed to elucidate the effect of laser-produced microchannels on pre-osteoblast maturation. Pre-osteoblast human embryonic palatal mesenchymal cells were seeded on a titanium plate treated with grinding (G), sandblasting with large grit and acid etching (SLA), or laser irradiation (L) for 3-18 days. The proliferation and morphology of pre-osteoblasts were evaluated using a Trypan Blue dye exclusion test and fluorescence microscopy. The mRNA expression, protein expression, and protein secretion of osteogenic differentiation markers in pre-osteoblasts were evaluated using reverse transcriptase quantitative polymerase chain reaction, a Western blot assay, and a multiplex assay, respectively. The extracellular calcium precipitation of pre-osteoblast was measured using Alizarin red S staining. Compared to G- and SLA-treated titanium surfaces, the laser-produced microchannel surfaces enhanced pre-osteoblast proliferation, the expression/secretion of osteogenic differentiation markers, and extracellular calcium precipitation. Laser-treated titanium implants may enhance the pre-osteoblast maturation process and provide extra benefits in clinical application.

Titanium Alloy Implants with Lattice Structures for Mandibular Reconstruction

In recent years, the field of mandibular reconstruction has made great strides in terms of hardware innovations and their clinical applications. There has been considerable interest in using computer-aided design, finite element modelling, and additive manufacturing techniques to build patient-specific surgical implants. Moreover, lattice implants can mimic mandibular bone's mechanical and structural properties. This article reviews current approaches for mandibular reconstruction, their applications, and their drawbacks. Then, we discuss the potential of mandibular devices with lattice structures, their development and applications, and the challenges for their use in clinical settings.

Tribocorrosion and Surface Protection Technology of Titanium Alloys: A Review

Titanium alloy has the advantages of high specific strength, good corrosion resistance, and biocompatibility and is widely used in marine equipment, biomedicine, aerospace, and other fields. However, the application of titanium alloy in special working conditions shows some shortcomings, such as low hardness and poor wear resistance, which seriously affect the long life and safe and reliable service of the structural parts. Tribocorrosion has been one of the research hotspots in the field of tribology in recent years, and it is one of the essential factors affecting the application of passivated metal in corrosive environments. In this work, the characteristics of the marine and human environments and their critical tribological problems are analyzed, and the research connotation of tribocorrosion of titanium alloy is expounded. The research status of surface protection technology for titanium alloy in marine and biological environments is reviewed, and the development direction and trends in surface engineering of titanium alloy are prospected.

Micro-arc oxidation (MAO) and its potential for improving the performance of titanium implants in biomedical applications

Titanium (Ti) and its alloys have good biocompatibility, mechanical properties and corrosion resistance, making them attractive for biomedical applications. However, their biological inertness and lack of antimicrobial properties may compromise the success of implants. In this review, the potential of micro-arc oxidation (MAO) technology to create bioactive coatings on Ti implants is discussed. The review covers the following aspects: 1) different factors, such as electrolyte, voltage and current, affect the properties of MAO coatings; 2) MAO coatings affect biocompatibility, including cytocompatibility, hemocompatibility, angiogenic activity, corrosion resistance, osteogenic activity and osseointegration; 3) antibacterial properties can be achieved by adding copper (Cu), silver (Ag), zinc (Zn) and other elements to achieve antimicrobial properties; and 4) MAO can be combined with other physical and chemical techniques to enhance the performance of MAO coatings. It is concluded that MAO coatings offer new opportunities for improving the use of Ti and its alloys in biomedical applications, and some suggestions for future research are provided.

Effects of hydroxyapatite-coated porous titanium scaffolds functionalized by exosomes on the regeneration and repair of irregular bone

As a traditional bone implant material, titanium (Ti) and its alloys have the disadvantages of lack of biological activity and susceptibility to stress shielding effect. Adipose stem cells (ADSCs) and exosomes were combined with the scaffold material in the current work to effectively create a hydroxyapatite (HA) coated porous titanium alloy scaffold that can load ADSCs and release exosomes over time. The composite made up for the drawbacks of traditional titanium alloy materials with higher mechanical characteristics and a quicker rate of osseointegration. Exosomes (Exos) are capable of promoting the development of ADSCs in porous titanium alloy scaffolds with HA coating, based on experimental findings from in vitro and in vivo research. Additionally, compared to pure Ti implants, the HA scaffolds loaded with adipose stem cell exosomes demonstrated improved bone regeneration capability and bone integration ability. It offers a theoretical foundation for the combined use of stem cell treatment and bone tissue engineering, as well as a design concept for the creation and use of novel clinical bone defect repair materials.

Antibacterial Structure Design of Porous Ti6Al4V by 3D Printing and Anodic Oxidation

Titanium alloy Ti6Al4V is a commonly used bone implant material, primarily prepared as a porous material to better match the elastic modulus of human bone. However, titanium alloy is biologically inert and does not have antibacterial properties. At the same time, the porous structure with a large specific surface area also increases the risk of infection, leading to surgical failure. In this paper, we prepared three porous samples with different porosities of 60%, 75%, and 85%, respectively (for short, 3D-60, 3D-75, and 3D-85) using 3D printing technology and clarified the mechanical properties. Through tensile experiments, when the porosity was 60%, the compressive modulus was within the elastic modulus of human bone. Anodic oxidation technology carried out the surface modification of a 3D-printed porous titanium alloy with 60% porosity. Through change, the different voltages and times on the TiO2 oxide layer on the 3D-printed porous titanium alloy are different, and it reveals the growth mechanism of the TiO2 oxide layer on a 3D-printed unique titanium alloy. The surface hydrophilic and antibacterial properties of 3D-printed porous titanium alloy were significantly improved after modification by anodic oxidation.

Preparation and properties of composite manganese/fluorine coatings on metallic titanium

Titanium is widely used in implants because of its good mechanical properties and biocompatibility. However, titanium has no biological activity and is prone to causing implant failure after implantation. In this study, we prepared a manganese- and fluorine-doped titanium dioxide coating on a titanium surface by microarc oxidation technology. The surface characteristics of the coating were evaluated by field emission scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and atomic force microscopy and profiler, and the corrosion resistance and wear resistance of the coating were also evaluated. The bioactivity of the coating on bone marrow mesenchymal stem cells was evaluated by in vitro cell experiments, and the antibacterial properties of the coating were evaluated by in vitro bacterial experiments. The results confirmed that the manganese- and fluorine-doped titanium dioxide coating was successfully prepared on the titanium surface, and manganese and fluorine were successfully introduced into the coating. The doping of manganese and fluorine did not change the surface morphology of the coating, and the coating had good corrosion resistance and wear resistance. The results of the in vitro cell experiment showed that the titanium dioxide coating with manganese and fluoride could promote the proliferation, differentiation and mineralization of bone marrow mesenchymal stem cells. The results of the bacterial experiment in vitro showed that the coating material could inhibit the propagation of Staphylococcus aureus and had a good antibacterial effect. Conclusion: it is feasible to prepare a manganese- and fluorine-doped titanium dioxide coating on titanium surfaces by microarc oxidation. The coating not only has good surface characteristics but also has good bone-promoting and antibacterial properties and has potential for clinical application.

Coating of manganese functional polyetheretherketone implants for osseous interface integration

Polyetheretherketone (PEEK) has been used extensively in biomedical engineering and it is highly desirable for PEEK implant to possess the ability to promote cell growth and significant osteogenic properties and consequently stimulate bone regeneration. In this study, a manganese modified PEEK implant (PEEK-PDA-Mn) was fabricated via polydopamine chemical treatment. The results showed that manganese was successfully immobilized on PEEK surface, and the surface roughness and hydrophilicity significantly improved after surface modification. Cell experiments in vitro demonstrated that the PEEK-PDA-Mn possesses superior cytocompatibility in cell adhesion and spread. Moreover, the osteogenic properties of PEEK-PDA-Mn were proved by the increased expression of osteogenic genes, alkaline phosphatase (ALP), and mineralization in vitro. Further rat femoral condyle defect model was utilized to assess bone formation ability of different PEEK implants in vivo. The results revealed that the PEEK-PDA-Mn group promoted bone tissue regeneration in defect area. Taken together, the simple immersing method can modify the surface of PEEK, giving outstanding biocompatibility and enhanced bone tissue regeneration ability to the modified PEEK, which could be applied as an orthopedic implant in clinical.

Advances in Multifunctional Bioactive Coatings for Metallic Bone Implants

To fix the bone in orthopedics, it is almost always necessary to use implants. Metals provide the needed physical and mechanical properties for load-bearing applications. Although widely used as biomedical materials for the replacement of hard tissue, metallic implants still confront challenges, among which the foremost is their low biocompatibility. Some of them also suffer from excessive wear, low corrosion resistance, infections and shielding stress. To address these issues, various coatings have been applied to enhance their in vitro and in vivo performance. When merged with the beneficial properties of various bio-ceramic or polymer coatings remarkable bioactive, osteogenic, antibacterial, or biodegradable composite implants can be created. In this review, bioactive and high-performance coatings for metallic bone implants are systematically reviewed and their biocompatibility is discussed. Updates in coating materials and formulations for metallic implants, as well as their production routes, have been provided. The ways of improving the bioactive coating performance by incorporating bioactive moieties such as growth factors, osteogenic factors, immunomodulatory factors, antibiotics, or other drugs that are locally released in a controlled manner have also been addressed.