Porous Tantalum Research Articles

Osteogenic differentiation of 3D-printed porous tantalum with nano-topographic modification for repairing craniofacial bone defects.

Introduction: Congenital or acquired bone defects in the oral and cranio-maxillofacial (OCMF) regions can seriously affect the normal function and facial appearance of patients, and cause great harm to their physical and mental health. To achieve good bone defect repair results, the prosthesis requires good osteogenic ability, appropriate porosity, and precise three-dimensional shape. Tantalum (Ta) has better mechanical properties, osteogenic ability, and microstructure compared to Ti6Al4V, and has become a potential alternative material for bone repair. The bones in the OCMF region have unique shapes, and 3D printing technology is the preferred method for manufacturing personalized prosthesis with complex shapes and structures. The surface characteristics of materials, such as surface morphology, can affect the biological behavior of cells. Among them, nano-topographic surface modification can endow materials with unique surface properties such as wettability and large surface area, enhancing the adhesion of osteoblasts and thereby enhancing their osteogenic ability. Methods: This study used 3D-printed porous tantalum scaffolds, and constructed nano-topographic surface through hydrothermal treatment. Its osteogenic ability was verified through a series of in vitro and in vivo experiments. Results: The porous tantalum modified by nano-topographic surface can promote the proliferation and osteogenic differentiation of BMSCs, and accelerate the formation of new bone in the Angle of the mandible bone defect of rabbits. Discussion: It can be seen that 3D-printed nano-topographic surface modified porous tantalum has broad application prospects in the repair of OCMF bone defects.

COMPARATIVE SURVIVAL OF CONTEMPORARY CEMENTLESS ACETABULAR COMPONENTS FOLLOWING PRIMARY TOTAL HIP ARTHROPLASTY

The last two decades have seen remarkable technological advances in total hip arthroplasty (THA) implant design. Porous ingrowth surfaces and highly crosslinked polyethylene (HXLPE) have been expected to dramatically improve implant survivorship. The purpose of the present study was to evaluate survival of contemporary cementless acetabular components following primary THA.16,421 primary THAs performed for osteoarthritis between 2000 and 2019 were identified from our institutional total joint registry. Patients received one of 12 contemporary cementless acetabular designs with HXLPE liners. Components were grouped based on ingrowth surface into 4 categories: porous titanium (n=10,952, mean follow-up 5 years), porous tantalum (n=1223, mean follow-up 5 years), metal mesh (n=2680, mean follow-up 6.5 years), and hydroxyapatite (HA) coated (n=1566, mean follow-up 2.4 years). Kaplan-Meier analyses were performed to assess the survivorship free of acetabular revision. A historical series of 182 Harris-Galante-1 (HG-1) acetabular components was used as reference.The 15-year survivorship free of acetabular revision was >97% for all 4 contemporary cohorts. Compared to historical control, porous titanium (HR 0.06, 95% CI 0.02–0.17, p<0.001), porous tantalum (HR 0.09, 95%CI 0.03–0.29, p<0.001), metal mesh (HR 0.11, 95%CI 0.04–0.31, p<0.001), and HA-coated (HR 0.14, 95%CI 0.04–0.48, p=0.002) ingrowth surfaces had significantly lower risk of any acetabular revision. There were 16 cases (0.1%) of acetabular aseptic loosening that occurred in 8 (0.07%) porous titanium, 5 (0.2%) metal mesh, and 3 (0.2%) HA-coated acetabular components. 7 of the 8 porous titanium aseptic loosening cases occurred in one known problematic design. There were no cases of aseptic loosening in the porous tantalum group.Modern acetabular ingrowth surfaces and HXLPE liners have improved on historical results at the mid-term. Contemporary designs have extraordinarily high revision-free survivorship, and aseptic loosening is now a rare complication.At mid-term follow-up, survivorship of contemporary uncemented acetabular components is excellent and aseptic loosening occurs in a very small minority of patients.

Comparison of the Mechanical and Osseointegrative Performance of Porous Tantalum and Titanium for Acetabular Implantation in Total Hip Arthroplasty: A Literature Review

Introduction: Stability of the acetabular component is a critical factor in the success of primary and revision total hip arthroplasty (THA) procedures. As such, the identification of implant surface characteristics that maximize stability of the acetabular cup is an important research objective. While titanium has historically been the most commonly used implant material, the proportion of THA procedures utilizing porous tantalum (PTa) implants has increased in recent years. The objective of this review is to examine the comparative mechanical and osseointegrative performance of PTa and porous titanium (PTi) and interpret these results in the context of primary and secondary stability of acetabular implants in THA, as characterized by strength of initial mechanical attachment and successful interlocking at the bone-implant interface, respectively. Methods: A literature search using a predetermined protocol and inclusion criteria yielded 7 articles presenting results of comparative testing of mechanical performance or osseointegration of PTa and PTi in the context of THA. Results: Neither PTa nor PTi presented consistently superior results in mechanical tests designed to correlate to primary stability at the metallo-biological surface nor in measures of osseointegration intended to represent secondary stability in THA. Discussion: In comparing PTa and PTi, it appears that the characteristics of the implant coating's pores may have a more significant impact on factors affecting the stability of an acetabular cup implant than the metal selected. However, determining the ideal pore morphology for this application is complex; pore characteristics that would suggest mechanical compatibility may conflict with those that would encourage more effective osseointegration. Conclusion: When extrapolated to be indicators of hypothetical clinical success, the results of this review are consistent with those of recently released macro-analyses of clinical outcomes: PTa and PTi acetabular cups, as they are currently manufactured, produce clinically equivalent outcomes. In the development and comparison of coating options, pore morphology and its complex effects on stability must be adequately accounted for; only then can we reach a faithful conclusion regarding the ideal porous adhesion surface for acetabular implant in THA.

Design of Ti64/Ta Hybrid Materials by Powder Metallurgy Mimicking Bone Structure.

This work reports on the fabrication of a novel two-layer material composed of a porous tantalum core and a dense Ti6Al4V (Ti64) shell by powder metallurgy. The porous core was obtained by mixing Ta particles and salt space-holders to create large pores, the green compact was obtained by pressing. The sintering behavior of the two-layer sample was studied by dilatometry. The interface bonding between the Ti64 and Ta layers was analyzed by SEM, and the pore characteristics were analyzed by computed microtomography. Images showed that two distinct layers were obtained with a bonding achieved by the solid-state diffusion of Ta particles into Ti64 during sintering. The formation of β-Ti and α' martensitic phases confirmed the diffusion of Ta. The pore size distribution was in the size range of 80 to 500 µm, and a permeability value of 6 × 10-10 m2 was close to the trabecular bones one. The mechanical properties of the component were dominated mainly by the porous layer, and Young's modulus of 16 GPa was in the range of bones. Additionally, the density of this material (6 g/cm3) was much lower than the one of pure Ta, which helps to reduce the weight for the desired applications. These results indicate that structurally hybridized materials, also known as composites, with specific property profiles can improve the response to osseointegration for bone implant applications.

Fabrication, bacteriostasis and osteointegration properties researches of the additively-manufactured porous tantalum scaffolds loading vancomycin.

Infected bone defects (IBDs) remains a challenging problem for orthopedists. Clinically, routine management for IBDs has two stages: debridement and systematic antibiotics administration to control infection, and secondary grafting to repair bone defects. Whereas the efficacy is not satisfactory, because the overuse of antibiotics may lead to systemic toxicity, and the emergence of drug-resistant bacteria, as well as the secondary surgery would cause additional trauma and economic burden to the patients. Therefore, it is imperative to develop a novel scaffold for one-stage repair of IBDs. In this study, vancomycin (Van) was encapsulated into poly(lactic co-glycolic acid) (PLGA) microspheres through the double emulsion method, which were then loaded into the additively-manufactured porous tantalum (AM-Ta) through gelatin methacryloyl (GelMA) hydrogel to produce the composite Ta/GelMA hydrogel (Gel)/PLGA/vancomycin(Van) scaffolds for repairing IBDs. Physiochemical characterization of the newly-developed scaffold indicated that the releasing duration of Van was over 2 weeks. Biological experiments indicated good biocompatibility of the composite scaffold, as well as bacteriostasis and osteointegration properties, which showed great potential for clinical application. The construction of this novel scaffold would provide new sight into the development of orthopaedic implants, shedding a novel light on the treatment of IBDs.

Combination therapy with BMSCs‑exosomes and porous tantalum for the repair of femur supracondylar defects.

In the field of orthopedics, defects in large bones have proven challenging to resolve. The aim of the present study was to address this problem through the combination of tantalum metal (pTa) with exosomes derived from bone marrow mesenchymal stem cells (BMSCs), which have the potential to enhance regeneration of full thickness femoral bone defects in rats. Cell culture results demonstrated that exosomes improved the proliferation and differentiation of BMSCs. Following establishment of a supracondylar femoral bone defect, exosomes and pTa were implanted into the defect area. Results demonstrated that pTa acts as a core scaffold for cell adhesion and exhibits good biocompatibility. Moreover, micro‑CT scan results as well as histological examination demonstrated that pTa had a significant effect on osteogenesis, with the addition of exosomes further promoting bone tissue regeneration and repair. In conclusion, this novel composite scaffold can effectively promote bone regeneration in large bone defect areas, providing a new approach for the treatment of large bone defects.

Application of Nano-Calcium Phosphate Coated Porous Tantalum Scaffold in Repair of Rabbit Cartilage Defect

Calcium coated scaffolds and their role in repair of bone defects have been widely studied in the last decades. This study aimed to evaluate the effect of bone morphogenetic protein-7 (BMP-7) loaded nano-calcium phosphate (CaP) coated porous tantalum scaffolds (PTS) on regenerative and reparative potency of cartilage defects in rabbits. We used New Zealand white rabbit cartilage defect models. The subjects were randomly grouped into 4: (1) a control group (no treatment), (2) a PTS group, (3) a CaP/PTS group, and (4) a CaP/PTS/BMP-7 groups. The characterization and in vitro biocompatibility of each scaffold were evaluated. Following scaffold implantation, we evaluated the gross observation score, Micro-CT observation parameters, and the mRNA of target genes. No visible difference was detected in water contact angle (WCA) and cell proliferation activity after co-culture among the PTS, CaP/PTS, and CaP/PTS/BMP-7 scaffold groups (P >0.05). Gross observation scores, trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular mineral density (TMD), bone volume fraction (BV/TV), COL2A1, SOX-9, Aggrecan, and RUNX-2 showed an obvious increase among the PTS, CaP/PTS, and CaP/PTS/BMP-7 groups to those with no treatment (P <0.05). Also, the PPARγ showed an obvious decline (P <0.05). Gross observation scores, Tb.Th, Tb.N, TMD, BV/TV, COL2A1, SOX-9, Aggrecan, and RUNX-2 increased and PPARγ decreased in CaP/PTS/BMP-7 group to PTS and CaP/PTS groups (P <0.05). Our findings indicate that PT scaffolds enhance the reparative potency of cartilage defects in New Zealand rabbits promoted the repair of cartilage defects in rabbits. This effect is boosted among those treated with the BMP-7 loaded nano-CaP coated PTS, and this group showed improved regenerative and reparative potency.

Compressive fatigue behavior of graded tantalum scaffolds produced by electron beam powder bed fusion

In this study, graded tantalum scaffolds were manufactured by electron beam powder bed fusion (EB-PBF). Compression-compression fatigue testing was conducted on the EB-PBF built graded tantalum scaffolds. The compressive fatigue behavior and compressive fatigue strength of graded tantalum scaffolds with vertical gradient (VG) and parallel gradient (PG) states were investigated. In the fatigue testing, the failure of PG graded scaffold was concentrated on the lowest strength constituent, resulting in higher cyclic ratcheting strain and fatigue damage strain. In terms of the VG graded scaffold, due to the simultaneous uniform deformation of each structure, the strain accumulation in a single cycle was small, resulting in the low cyclic ratcheting strain. In addition, the propagation of fatigue cracks in pore structure with higher strength can be retarded by the stress redistribution, resulting in the low fatigue damage strain. Therefore, the design idea of graded pore structure under identical strain condition is beneficial to obtain porous tantalum scaffold with high compressive fatigue strength.

Design and biomechanical analysis of patientspecific porous tantalum prostheses for knee joint revision surgery.

Artificial joint revision surgery, as an increasingly common surgery in orthopedics, often requires patient-specific prostheses to repair the bone defect. Porous tantalum is a good candidate due to its excellent abrasion and corrosion resistance and good osteointegration. Combination of 3D printing technology and numerical simulation is a promising strategy to design and prepare patient-specific porous prostheses. However, clinical design cases have rarely been reported, especially from the viewpoint of biomechanical matching with the patient's weight and motion and specific bone tissue. This work reports a clinical case on the design and mechanical analysis of 3D-printed porous tantalum prostheses for the knee revision of an 84-year-old male patient. Particularly, standard cylinders of 3D-printed porous tantalum with different pore size and wire diameters were first fabricated and their compressive mechanical properties were measured for following numerical simulation. Subsequently, patientspecific finite element models for the knee prosthesis and the tibia were constructed from the patient's computed tomography data. The maximum von Mises stress and displacement of the prostheses and tibia and the maximum compressive strain of the tibia were numerically simulated under two loading conditions by using finite element analysis software ABAQUS. Finally, by comparing the simulated data to the biomechanical requirements for the prosthesis and the tibia, a patient-specific porous tantalum knee joint prosthesis with a pore diameter of 600 μm and a wire diameter of 900 μm was determined. The Young's modulus (5719.32 ± 100.61 MPa) and yield strength (172.71 ± 1.67 MPa) of the prosthesis can produce both sufficient mechanical support and biomechanical stimulation to the tibia. This work provides a useful guidance for designing and evaluating a patient-specific porous tantalum prosthesis.

Trabecular Bone Remodeling After Posterior Lumbar Interbody Fusion: Comparison of Three-Dimensional Porous Tantalum and Titanium-Coated Polyetheretherketone Interbody Cages.

Retrospective cohort study. The criteria for determining completion of intervertebral stability after posterior lumbar interbody fusion (PLIF) remain controversial. Several new radiological indicators of bone growth and osteointegration have been established. We compared computed tomography (CT) findings related to osteointegration after PLIF with interbody cages of two different materials and designs. We retrospectively analyzed data from 103 patients who underwent PLIF with three-dimensional porous tantalum (Tn) cages or titanium-coated polyetheretherketone (TiP) cages. CT images obtained 3months and 1year after surgery were examined for trabecular bone remodeling (TBR), cancellous condensation (CC), and vertebral endplate cyst (VEC) formation. The incidences of each finding were compared by cage type, and rates of instrument failure and pseudarthrosis were determined. Three months postoperatively, 87% of the levels with Tn cages exhibited TBR, whereas 96% of those with TiP cages did not (P < .001). Most levels with Tn cages levels exhibited TBR and no CC 3months (81%) and 1 year (94%) after surgery. Although 78% of levels with TiP cages exhibited CC and no TBR 3months after surgery, 59% exhibited both CC and TBR 1 year after surgery. Significantly fewer VECs formed around the Tn cages than around the TiP cages both 3months (P = .002) and 1year (P < .001) after surgery. Implant-related problems occurred at levels that exhibited neither TBR nor CC. The porous tantalum cage may enable intervertebral stability that is comparable to bony fusion soon after surgery.

Long-Term Results of Anodic and Thermal Oxidation Surface Modification on Titanium and Tantalum Implants

Tantalum and titanium are two of the most popular materials used in dental implants today. These materials are highly biocompatible, durable, and long-lasting, making them ideal for use in dental and maxillofacial implants. The ceramic oxide layer that covers the surface of titanium and tantalum implants (TiO2,TaO2) is formed through an electrochemical growth from the inside of the metal and subsequently altered through heat treatment. The aim of this retrospective study was to evaluate the long-term survival of the oxide ceramic-coated titanium dental implants. The secondary purpose was to evaluate the production process and the cost of the coated tantalum and titanium implants, and to complete these retrospective investigations with the results of our previous work concerning the titanium oxide coating. The structural, physical, and chemical properties as well as the corrosion resistance of the Ti/TiO2 surface were investigated; XPS, SIMS, and XRD techniques were used. Patients who received tantalum oxide-coated (Ta/TaO2) dental implants, titanium oxide-coated (Ti/TiO2) dental implants, or titanium oxide-coated (Ti/TiO2) osteosynthesis plates for rehabilitation at the Department of Oro-Maxillofacial Surgery and Stomatology, Semmelweis University between 1995 and 2005 were included in this retrospective study. Data collection was performed between June 2021 and December 2021. The cost of the tantalum implant was 25 times that of the titanium implant. Only 21 implants were inserted in 10 patients. The survival rate (min. 16 years) was 95%. Twelve patients with a total of sixty-four TiO2-coated implants were observed. The mean implant survival rate was 95%. Our conclusion was that, regardless of the shape of the implant, the Ti/TiO2 coating proved its excellent durability over the years. The “tantalum issue” is increasingly relevant nowadays, since instead of implants made of pure tantalum metal, implants with a porous tantalum surface have come to the fore.

Preparation, modification, and clinical application of porous tantalum scaffolds.

Porous tantalum (Ta) implants have been developed and clinically applied as high-quality implant biomaterials in the orthopedics field because of their excellent corrosion resistance, biocompatibility, osteointegration, and bone conductivity. Porous Ta allows fine bone ingrowth and new bone formation through the inner space because of its high porosity and interconnected pore structure. It contributes to rapid bone integration and long-term stability of osseointegrated implants. Porous Ta has excellent wetting properties and high surface energy, which facilitate the adhesion, proliferation, and mineralization of osteoblasts. Moreover, porous Ta is superior to classical metallic materials in avoiding the stress shielding effect, minimizing the loss of marginal bone, and improving primary stability because of its low elastic modulus and high friction coefficient. Accordingly, the excellent biological and mechanical properties of porous Ta are primarily responsible for its rising clinical translation trend. Over the past 2decades, advanced fabrication strategies such as emerging manufacturing technologies, surface modification techniques, and patient-oriented designs have remarkably influenced the microstructural characteristic, bioactive performance, and clinical indications of porous Ta scaffolds. The present review offers an overview of the fabrication methods, modification techniques, and orthopedic applications of porous Ta implants.

THE IMPORTANCE OF PRESS-FIT AND THREE-POINT FIXATION IN TREATING LARGE ACETABULAR DEFECTS WITH POROUS TANTALUM COMPONENTS

First-time revision acetabular components have a 36% re-revision rate at 10 years in Australia, with subsequent revisions known to have even worse results. Acetabular component migration &gt;1mm at two years following revision THA is a surrogate for long term loosening. This study aimed to measure the migration of porous tantalum components used at revision surgery and investigate the effect of achieving press-fit and/or three-point fixation within acetabular bone.Between May 2011 and March 2018, 55 patients (56 hips; 30 female, 25 male) underwent acetabular revision THR with a porous tantalum component, with a post-operative CT scan to assess implant to host bone contact achieved and Radiostereometric Analysis (RSA) examinations on day 2, 3 months, 1 and 2 years. A porous tantalum component was used because the defects treated (Paprosky IIa:IIb:IIc:IIIa:IIIb; 2:6:8:22:18; 13 with pelvic discontinuity) were either deemed too large or in a position preventing screw fixation of an implant with low coefficient of friction. Press-fit and three-point fixation of the implant was assessed intra-operatively and on postoperative imaging.Three-point acetabular fixation was achieved in 51 hips (92%), 34 (62%) of which were press-fit. The mean implant to host bone contact achieved was 36% (range 9-71%). The majority (52/56, 93%) of components demonstrated acceptable early stability. Four components migrated &gt;1mm proximally at two years (1.1, 3.2, 3.6 and 16.4mm). Three of these were in hips with Paprosky IIIB defects, including 2 with pelvic discontinuity. Neither press-fit nor three-point fixation was achieved for these three components and the cup to host bone contact achieved was low (30, 32 and 59%).The majority of porous tantalum components had acceptable stability at two years following revision surgery despite treating large acetabular defects and poor bone quality. Components without press-fit or three-point fixation were associated with unacceptable amounts of early migration.

Biomechanical study of internal fixation methods for femoral neck fractures based on Pauwels angle.

Objective: To select the most appropriate internal fixation method based on the Pauwels angle, in order to provide a new concept for clinical accurate treatment of femoral neck fractures (FNFs). Methods: FNFs models of Pauwels ; ; ; were created respectively. For Pauwels ≤ , 1, 2 and 3 Cannulated Compression Screws (CCS) and Porous Tantalum Screws (PTS) were used to fix the fracture for the models. For Pauwels , 3CCS and Medial Buttress Plate (MBP) combined with 1, 2 and 3CCS were used to fix the fracture. Based on the results of the finite element (FE) analysis, the biomechanical properties of each model were compared by analyzing and evaluating the following four parameters: maximal stress of the bone (MBS), maximal stress of the implants (MIS), maximal displacement of bone (MBD), interfragmentary motion (IFM). Results: At Pauwels , the larger parameters were found in 1CCS, which was 94.8MPa (MBS), 307.7MPa (MIS), 0.86mm (MBD) and 0.36mm (IFM). In 2CCS group, the parameters were 86.1MPa (MBS), 254.4MPa (MIS), 0.73mm (MBD) and 0.27mm (IFM), which were similar to those of PTS. At Pauwels ; , with the increase of the number of used CCS, accordingly, the parameters decreased. Particularly, the MIS (Pauwels ) of 1CCS was 1,195.3 MPa, but the other were less than the yield range of the materials. At Pauwels , the MBS of 3CCS group was 128.6 Mpa, which had the risk of failure. In 2CCS + MBP group, the parameters were 124.2MPa (MBS), 602.5MPa (MIS), 0.75mm (MBD) and 0.48mm (IFM), The model stability was significantly enhanced after adding MBP. Conclusion: Pauwels type Ⅰ (< ) fractures can reduce the number of CCS, and PTS is an appropriate alternative treatment. For Pauwels type Ⅱ fractures ( ), the 3CCS fixation method is still recommended. For Pauwels type Ⅲ fractures (> ), it is recommended to add MBP to the medial femoral neck and combine with 2CCS to establish a satisfactory fracture healing environment.

Fabrication of Porous Tantalum with Low Elastic Modulus and Tunable Pore Size for Bone Repair.

Porous tantalum (Ta) is a potential bone substitute due to its excellent biocompatibility and desirable mechanical properties. In this work, a series of porous Ta materials with interconnected micropores and varying pore sizes from 23 to 210 μm were fabricated using spark plasma sintering. The porous structure was formed by thermal decomposition of ammonium bicarbonate powder premixed in the Ta powder. The pore size and porosity were controlled by the categorized particle size of ammonium bicarbonate. The porous Ta has elastic moduli in the range of 2.1-3.2 GPa and compressive yield strength in the range of 23-34 MPa, which are close to those of human bone. In vitro, as-fabricated porous Ta demonstrates excellent biocompatibility by supporting adhesion and proliferation of preosteoblasts. In vivo studies also validate its bone repair capability after implantation in a rat femur defect model. The study demonstrates a facile strategy to fabricate porous Ta with controllable pore size for bone repair.

Influence of porosity on osteogenesis, bone growth and osteointegration in trabecular tantalum scaffolds fabricated by additive manufacturing.

Porous tantalum implants are a class of materials commonly used in clinical practice to repair bone defects. However, the cumbersome and problematic preparation procedure have limited their widespread application. Additive manufacturing has revolutionized the design and process of orthopedic implants, but the pore architecture feature of porous tantalum scaffolds prepared from additive materials for optimal osseointegration are unclear, particularly the influence of porosity. We prepared trabecular bone-mimicking tantalum scaffolds with three different porosities (60%, 70% and 80%) using the laser powder bed fusing technique to examine and compare the effects of adhesion, proliferation and osteogenic differentiation capacity of rat mesenchymal stem cells on the scaffolds in vitro. The in vivo bone ingrowth and osseointegration effects of each scaffold were analyzed in a rat femoral bone defect model. Three porous tantalum scaffolds were successfully prepared and characterized. In vitro studies showed that scaffolds with 70% and 80% porosity had a better ability to osteogenic proliferation and differentiation than scaffolds with 60% porosity. In vivo studies further confirmed that tantalum scaffolds with the 70% and 80% porosity had a better ability for bone ingrowh than the scaffold with 60% porosity. As for osseointegration, more bone was bound to the material in the scaffold with 70% porosity, suggesting that the 3D printed trabecular tantalum scaffold with 70% porosity could be the optimal choice for subsequent implant design, which we will further confirm in a large animal preclinical model for better clinical use.

3D-Printed Porous Tantalum Scaffold Improves Muscle Attachment via Integrin-β1-Activated AKT/MAPK Signaling Pathway.

3D-printed porous titanium (Ti) alloy scaffolds have been reported for facilitating muscle attachment in our previous study. However, the anti-avulsion ability needs to be improved. In this study, we used 3D-printed porous tantalum (Ta) scaffolds to improve muscle attachment. The differences in chemical and physical characteristics and muscle adhesion between the two scaffolds were tested and compared in the gene and protein level both in vitro and in vivo. The possible molecular mechanism was analyzed and further proved. The results showed that compared with the porous Ti alloy, porous Ta had better cell proliferation, differentiation, migration, and adhesion via the integrin-β1 (Itgb1)-activated AKT/MAPK signaling pathway in L6 rat myoblasts. When artificially down-regulated the expression of Itgb1, cell adhesion and myogenesis differentiation were affected and the phosphorylation of the AKT/MAPK signaling pathway was suppressed. In rat intramuscular implantation, porous Ta had a significantly higher muscle ingrowth rate (85.63% ± 4.97 vs 65.98% ± 4.52, p < 0.01) and larger avulsion force (0.972 vs 0.823 N/mm2, p < 0.05) than the porous Ti alloy. These findings demonstrate that the 3D-printed porous Ta scaffold is beneficial for further clinical application of muscle attachment.

Tantalum as Trabecular Metal for Endosseous Implantable Applications

During the last 20 years, tantalum has known ever wider applications for the production of endosseous implantable devices in the orthopedic and dental fields. Its excellent performances are due to its capacity to stimulate new bone formation, thus improving implant integration and stable fixation. Tantalum's mechanical features can be mainly adjusted by controlling its porosity thanks to a number of versatile fabrication techniques, which allow obtaining an elastic modulus similar to that of bone tissue, thus limiting the stress-shielding effect. The present paper aims at reviewing the characteristics of tantalum as a solid and porous (trabecular) metal, with specific regard to biocompatibility and bioactivity. Principal fabrication methods and major applications are described. Moreover, the osteogenic features of porous tantalum are presented to testify its regenerative potential. It can be concluded that tantalum, especially as a porous metal, clearly possesses many advantageous characteristics for endosseous applications but it presently lacks the consolidated clinical experience of other metals such as titanium.

Effects of Unit Cell Topology on the Mechanical Properties of Porous Tantalum Structures via Laser Powder Bed Fusion

Additive manufacturing (AM) of porous tantalum scaffolds receives extensive attention because the demands for tantalum implants grow rapidly. Understanding the effects of unit cell topology on the mechanical properties of porous tantalum scaffold structures is critical for durable implant design, but it is still lacking. Herein, porous tantalum structures with two types of unit cells (body‐centered cubic [BCC] and body‐centered cubic deformation [BCC‐D]) are additively manufactured with laser powder bed fusion (LPBF). The geometric characteristics and mechanical properties of the manufactured structures are comparatively studied. It is found that the mechanical properties of BCC porous tantalum in the building and horizontal directions are discovered to be nearly identical, with elastic modulus and yield strength of nearly 1.9 GPa and 56 MPa, respectively. Unit cell topology dominates the mechanical anisotropy and compressive failure mode of porous tantalum. The mechanical properties of the BCC‐D topology are anisotropic, and the fracture morphology indicates that it is a cleavage fracture and a minor ductile fracture. The capacity to finely control the mechanical properties of porous tantalum structure through unit cell topology is prominent for optimizing implant structure for personalized medical care.

A novel biomimetic trabecular bone metal plate for bone repair and osseointegration.

Fracture is one of the most common traumatic diseases in clinical practice, and metal plates have always been the first choice for fracture treatment because of their high strength. However, the bone plates have high elastic modulus and do not match the biomechanics of human bone, which adversely affects callus formation and fracture healing. Moreover, the complex microenvironment in the human body can induce corrosion of metallic materials and release toxic ions, which reduces the biocompatibility of the bone plate, and may necessitate surgical removal of the implant. In this study, tantalum (Ta) was deposited on porous silicon carbide (SiC) scaffolds by chemical vapor deposition technology to prepare a novel porous tantalum (pTa) trabecular bone metal plate. The function of the novel bone plate was evaluated by implantation in an animal fracture model. The results showed that the novel bone plate was effective in fracture fixation, without breakage. Both X-ray and microcomputed tomography analysis showed indirect healing by both pTa trabecular bone metal plates and titanium (Ti) plates; however, elastic fixation and obvious callus formation were observed after fixation with pTa trabecular bone metal plates, indicating better bone repair. Histology showed that pTa promoted the formation of new bone and integrated well with the host bone. Therefore, this novel pTa trabecular bone metal plate has good prospects for application in treating fractures.