The proliferation and phenotypic expression of human osteoblasts on tantalum metal

3Y-TZP/Ta Biocermet as a Dental Material: An Analysis of the In Vitro Adherence of Streptococcus Oralis Biofilm and an In Vivo Pilot Study in Dogs

The surface adhesion of bacterial cells and the in vivo biocompatibility of a new ceramic-metal composite made of zirconium dioxide and tantalum were evaluated. Within the framework of an in vitro study using the crystal violet staining and colony counting methods, a relatively similar adhesion of Streptococcus oralis to the 3Y-TZP/Ta biocermet (roughness Ra = 0.12 ± 0.04 µm) and Ti-Al6-V4 titanium alloy (Ra = 0.04 ± 0.01 µm) was found. In addition, in an in vivo preliminary study focused on the histological analysis of a series of rods implanted in the jaws of beagle dogs for a six-month period, the absence of any fibrous tissue or inflammatory reaction at the interface between the implanted 3Y-TZP/Ta biocermets and the new bone was found. Thus, it can be concluded that the developed ceramic-metal biocomposite may be a promising new material for use in dentistry.

Multidimensional analysis for the correlation of physico-chemical attributes to osteoblastogenesis in TiNbZrSnTa alloys

Data-enabled approaches that complement experimental testing offer new capabilities to investigate the interplay between chemical, physical and mechanical attributes of alloys and elucidate their effect on biological behaviours. Reported here, instead of physical causation, statistical correlations were used to study the factors responsible for the adhesion, proliferation and maturation of pre-osteoblasts MC3T3-E1 cultured on Titanium alloys. Eight alloys with varying wt% of Niobium, Zirconium, Tin and Tantalum (Ti- (2-22 wt%)Nb- (5-20 wt%)Zr- (0-18 wt%)Sn- (0-14 wt%)Ta) were designed to achieve exemplars of allotropes (incl., metastable-β, β + α', α″). Following confirmation of their compositions (ICP, EDX) and their crystal structure (XRD, SEM), their compressive bulk properties were measured and their surface features characterised (XPS, SFE). Because these alloys are intended for the manufacture of implantable orthopaedic devices, the correlation focuses on the effect of surface properties on cellular behaviour. Physico-chemical attributes were paired to biological performance, and these highlight the positive interdependencies between oxide composition and proliferation (esp. Ti4+), and maturation (esp. Zr4+). The correlation reveals the negative effect of oxide thickness, esp. TiOx and TaOx on osteoblastogenesis. This study also shows that the characterisation of the chemical state and elemental electronic structure of the alloys' surface is more predictive than physical properties, namely SFE and roughness.

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.

Analysis of Factors Influencing Postoperative Femoral Head Collapse in Patients With Ficat I, II, and III Stages of Aseptic Necrosis of the Femoral Head

OBJECTIVE

To investigate the factors influencing postoperative femoral head collapse (FHC) in patients with Ficat I, II, and III stages of aseptic necrosis of the femoral head (ANFH).

METHODS

Retrospective analysis of 178 patients with ANFH admitted to our hospital from October 2018 to October 2021 was studied, and patients were categorized into the FHC group and no FHC group according to whether FHC occurred after surgery. The influencing factors causing postoperative FHC were analyzed by univariate and multifactor logistic regression.

RESULTS

In the collapsed group, there were statistically significant differences in etiology, extent of necrosis, mechanism of injury, preoperative waiting time, Japanese Femoral Necrosis Research Society staging, distance from the tip of the tantalum rod to the center of necrosis, and Harris score after treatment ( P < 0.05). The etiology, extent of necrosis, mechanism of injury, preoperative waiting time, Japanese Femoral Osteonecrosis Research Society classification, distance between the tantalum rod tip and the center of necrosis, and Harris score after treatment were set as independent variables, and postoperative FHC in patients with Ficat I, II, and III stages of ANFH was used as the dependent variable in the univariate logistic regression analysis.

DISCUSSION

Hormonal osteonecrosis of the femur, extent of necrosis, type C1 and type C2 in the Japanese Society for the Study of Femoral Osteonecrosis staging, and distance of the tip of the tantalum rod from the center of necrosis are risk factors for postoperative FHC in patients with Ficat I, II, and III stages of ANFH.

Use of Customized 3D-Printed Titanium Augment With Tantalum Trabecular Cup for Large Acetabular Bone Defects in Revision Total Hip Arthroplasty: A Midterm Follow-Up Study

Aims: In revision total hip arthroplasty (THA), large acetabular bone defects pose challenges for surgeons. Recently, wide application of trabecular tantalum, which has outstanding biocompatibility and mechanical properties, and the development of three-dimensional (3D) printing have led to the introduction of new schemes for acetabular reconstruction. However, few studies have focused on the treatment of bone defects with customized 3D-printed titanium augments combined with tantalum trabecular cup. Thus, we aimed to evaluate the effect of this therapy in patients who underwent revision THAs.

Patients and Methods: We included 23 patients with Paprosky type III acetabular bone defects who underwent revision THA between January 2013 and June 2019. The preoperative hip rotation center and functional score were compared with those at 2–7 years (average 4.7 years) postoperatively to evaluate the midterm prognosis of our treatment choice.

Results: Postoperatively, the rotation centres of all hips were comparable with those of the contralateral hips. Hip function improved with average Harris Hip Score improved from 33.5 (22.7–40.2) to 86.1 (73.5–95.6) and average Oxford Hip Score improved from 8.3 (0–14) to 38.8 (35–48) during follow-up. One dislocation, which occurred due to extreme hip flexion within 6 weeks, was treated with closed reduction, and no recurrent dislocation occurred. No nerve injury, infection, aseptic loosening, or osteolysis were observed and no re-revision was performed in any patient.

Conclusion: Satisfactory midterm outcomes were obtained with 3D-printed titanium augment combined with tantalum cup for the treatment of acetabular defects in revision THA. Changes in the Harris Hip Score and Oxford Hip Score suggested a significant improvement in hip function.

The use of tantalum cones and diaphyseal-engaging stems in tibial component revision: a consecutive series

INTRODUCTION

Revision knee arthroplasty presents a number of challenges, including management of bone loss. The goal in managing moderate to large bone defects is fixation that is sufficient enough to allow early weight-bearing. The purpose of this study was to describe the surgical technique and clinical and radiographic outcomes of patients treated with porous tantalum metaphyseal cones in combination with long uncemented diaphyseal-engaging stems to manage tibial bone loss in revision total knee arthroplasty (TKA).

MATERIALS AND METHODS

Thirty-six aseptic revision TKAs were performed at our institution between 2016 and 2019 by two senior authors. A single trabecular metal tantalum cone combined with a long (100 or 155 mm) press fit, diaphyseal-engaging stem was used in all cases to reconstruct metaphyseal bone defects and to augment tibial fixation. Cemented stems were excluded. The tibiofemoral angle was measured along the tibial and femoral shaft axes on the weight-bearing anteroposterior radiograph at final follow-up (range 15-56 months). All clinical and surgical complications, reoperations, and revisions of any component were recorded. Survivorship free of revision was evaluated at the time of the latest follow-up.

RESULTS

The mean Knee Society Score (KSS) and Knee Society Function Score (KSS-F) improved significantly from 29.7 points preoperatively (range 11-54 points) to 86 points (range 43-99 points) and from 20.4 points preoperatively (range 0-55 points) to 72.3 points (range 30-90 points) (p < 0.05), respectively. Eleven tibial constructs (30.5%) had incomplete, nonprogressive radiolucent lines (≤ 2 mm). All tibial cones demonstrated osteointegration. One patient underwent a full revision for periprosthetic joint infection, and survivorship free of any component revision was 91.7% at final follow-up.

CONCLUSIONS

Hybrid fixation with uncemented diaphyseal-engaging stems and porous tantalum metaphyseal cones resulted in radiographic lack of osteolysis, good clinical outcomes, and survivorship of 91.7% at a median follow-up of 33 months when considering all-cause revision as the endpoint.

A comprehensive review of biological and materials properties of Tantalum and its alloys

Tantalum (Ta) and its alloys have been used for various cardiovascular, orthopedic, fracture fixation, dental, and spinal fusion implants. This review evaluates the biological and material properties of Ta and its alloys. Specifically, the biological properties including hemocompatibility and osseointegration, and material properties including radiopacity, MRI compatibility, corrosion resistance, surface characteristics, semiconductivity, and mechanical properties are covered. This review highlights how the material properties of Ta and its alloys contribute to its excellent biological properties for use in implants and medical devices.

Fatigue behaviour and biocompatibility of additively manufactured bioactive tantalum graded lattice structures for load-bearing orthopaedic applications

Laser powder bed fusion (LPBF) additive manufacturing of pure tantalum and their graded lattice structures was systematically investigated, with emphasis on their microstructure evolution, phase formation, surface energy and biological properties in comparison with conventionally forged pure Ta. The LPBF fabricated Ta (LPBF-Ta) exhibited lower contact angles and higher surface energy than the forged-Ta which indicated the better wettability of the LPBF-Ta. The adhesion and proliferation of rat bone marrow stromal cells (rBMSCs) were also enhanced for the LPBF-Ta when compared to forged-Ta. Three different Ta graded gyroid lattice structures (i.e., uniform structure, Y-gradient structure, Z-gradient structure) were designed and fabricated using the same optimised LPBF parameters. Y-gradient structures exhibited the best plateau stress and compressive modulus among three different graded structures due to the maximum local volume fraction on the fracture plane. In fatigue response, Y-gradient outperformed the other two gyroid structures under varying stresses. In terms of cell culture response, the uniform structures performed the best biocompatibility due to its suitable pore size for cell adhesion and growth. This study provides new and in-depth insights into the LPBF additive manufacturing of pure Ta graded lattice structures with desired fatigue and biological properties for load-bearing orthopaedic applications.

Tantalum as a Novel Biomaterial for Bone Implant: A Literature Review

Titanium (Ti) has been used in metallic implants since the 1950s due to various biocompatible and mechanical properties. However, due to its high Young’s modulus, it has been modified over the years in order to produce a better biomaterial. Tantalum (Ta) has recently emerged as a new potential biomaterial for bone and dental implants. It has been reported to have better corrosion resistance and osteo-regenerative properties as compared to Ti alloys which are most widely used in the bone-implant industry. Currently, Tantalum cannot be widely used yet due to its limited availability, high melting point, and high-cost production. This review paper discusses various manufacturing methods of Tantalum alloys, including conventional and additive manufacturing and also discusses their drawbacks and shortcomings. Recent research includes surface modification of various metals using Tantalum coatings in order to combine bulk material properties of different materials and the porous surface properties of Tantalum. Design modification also plays a crucial role in controlling bulk properties. The porous design does provide a lower density, wider surface area, and more immense specific strength. In addition to improved mechanical properties, a porous design could also escalate the material's biological and permeability properties. With current advancement in additive manufacturing technology, difficulties in processing Tantalum could be resolved. Therefore, Tantalum should be considered as a serious candidate material for future bone and dental implants.

Development of Fluorine-Free Tantalum Carbide MXene Hybrid Structure as a Biocompatible Material for Supercapacitor Electrodes

The application of nontoxic 2D transition-metal carbides (MXenes) has recently gained ground in bioelectronics. In group-4 transition metals, tantalum possesses enhanced biological and physical properties compared to other MXene counterparts. However, the application of tantalum carbide for bioelectrodes has not yet been explored. Here, fluorine-free exfoliation and functionalization of tantalum carbide MAX-phase to synthesize a novel Ta4C3Tx MXene-tantalum oxide (TTO) hybrid structure through an innovative, facile, and inexpensive protocol is demonstrated. Additionally, the application of TTO composite as an efficient biocompatible material for supercapacitor electrodes is reported. The TTO electrode displays long-term stability over 10 000 cycles with capacitance retention of over 90% and volumetric capacitance of 447 F cm-3 (194 F g-1) at 1 mV s-1. Furthermore, TTO shows excellent biocompatibility with human-induced pluripotent stem cells-derived cardiomyocytes, neural progenitor cells, fibroblasts, and mesenchymal stem cells. More importantly, the electrochemical data show that TTO outperforms most of the previously reported biomaterials-based supercapacitors in terms of gravimetric/volumetric energy and power densities. Therefore, TTO hybrid structure may open a gateway as a bioelectrode material with high energy-storage performance for size-sensitive applications.

Fabrication of Hydroxyapatite/Tantalum Composites by Pressureless Sintering in Different Atmosphere

The effect of sintering atmosphere (air and Ar) and temperature (1100, 1200, 1300 °C) on the microstructure, mechanical properties, and bioactivity of hydroxyapatite/tantalum (HA/Ta) composites were systematically investigated by pressureless sintering of the mixture of HA and Ta powders. It shows that the sintering atmosphere greatly impacts the phase composition and microstructure of the HA/Ta composites. The higher diffusion of atoms promotes shrinkage and causes deeper reaction fusion between the HA matrix and Ta, which improved the interfacial binding of the HA/Ta composites. The refined grain structure and improved interfacial binding obtained within the Ar atmosphere compared to the air atmosphere benefit the mechanical properties. The maximum bending strength and shrinkage observed for the composites sintered at 1300 °C in the Ar atmosphere are 27.24 MPa and 6.65%, respectively. The cell counting kit-8 (CCK-8) method was used to investigate the in vitro cytocompatibility of HA/Ta composites. The results revealed that the HA/Ta composites sintered with different conditions have no cytotoxicity. The simulated body fluid (SBF) soaking results showed that all of the studied composites possess desirable bioactivity, as demonstrated by their ability to form calcium-deficient carbonate apatite layer on the surfaces. For composites sintered at 1300 °C, the surface apatite layer coverage of the composites obtained in the Ar atmosphere was increased by 139.7% than the ones obtained in air, which confirmed an enhanced bioactive mineralization ability. The results indicated that the HA/Ta composites sintered at 1300 °C in Ar possess desirable mechanical properties and bioactivity. This work opens up the new possibility for preparing HA-based composites and is of great value in biomedical applications.

The Fate of Zone 2 Radiolucencies in Contemporary Highly Porous Acetabular Components: Not All Designs Perform Equally

Background

The enhanced frictional resistance of modern ultraporous acetabular components can impede complete seating; however, surgeons expect the enhanced ingrowth surface to resolve polar (zone 2) gaps over time via osseointegration. This study characterized zone 2 radiographic osseointegration in 3 acetabular component designs: 2 highly porous ingrowth and one traditional ongrowth.

Methods

A consecutive cohort of primary total hip arthroplasties was reviewed which utilized 3 different acetabular cup designs: ongrowth titanium with hydroxyapatite (HA), highly porous titanium with machined radial grooves (MRG), and dual-porous titanium substrate with micropore (MP). Radiographic analysis was performed using accepted measurement criteria with particular attention to radiolucent lines.

Results

Seven hundred ninety cases were available for analysis. Initial 1-month radiographs revealed 43.2% of HA, 78.2% of MRG, and 81.0% of MP cups exhibited zone 2 radiolucencies, consistent with incomplete seating. At 1 year, all HA radiolucencies resolved, whereas 46.2% and 34.7% of radiolucencies remained in MRG and MP cups, respectively (P ≤ .005). At minimum 2 years, a significant proportion of zone 2 radiolucencies remained in 46.0% of MRG compared with 23.9% of MP cups and 3.0% of HA cups (P ≤ .007).

Conclusion

The resolution of zone 2 radiolucencies at 1-year and minimum 2-year follow-up signified osseointegration for nearly all HA and most MP cups. Highly porous titanium cups with machined radial grooves demonstrated persistent zone 2 radiolucencies at 1 year and beyond. Given reports of early loosening with this particular acetabular implant, further follow-up is warranted as this study highlights that not all contemporary highly porous metal acetabular components perform equally.

Level of Evidence

III.

Porous tantalum oxide with osteoconductive elements and antibacterial core-shell nanoparticles: A new generation of materials for dental implants

Implant surfaces with cytocompatible and antibacterial properties are extremely desirable for the prevention of implant's infection and the promotion of osseointegration. In this work, both micro-arc oxidation (MAO) and DC magnetron sputtering techniques were combined in order to endow tantalum-based surfaces with osteoblastic cytocompatibility and antibacterial activity. Porous Ta₂O₅ layers containing calcium (Ca) and phosphorous (P) were produced by MAO (TaCaP) to mimic the bone tissue morphology and chemical composition (Ca/P ratio close to 1.67). Furthermore, zinc (Zn) nanoparticles were deposited onto the previous surfaces by DC magnetron sputtering without or with an additional thin carbon layer deposited over the nanoparticles (respectively, TaCaP-Zn and TaCaP-ZnC) to control the Zn ions (Zn²⁺) release. Before osteoblastic cell seeding, the surfaces were leached for three time-points in PBS. All modified samples were cytocompatible. TaCaP-Zn slightly impaired cell adhesion but this was improved in the samples leached for longer immersion times. The initial cell adhesion was clearly improved by the deposition of the carbon layer on the Zn nanoparticles, which also translated to a higher proliferation rate. Both Zn-containing surfaces presented antibacterial activity against S. aureus. The two surfaces were active against planktonic bacteria, and TaCaP-Zn also inhibited sessile bacteria. Attributing to the excellent in vitro performance of the nanostructured Ta surface, with osteoconductive elements by MAO followed by antimicrobial nanoparticles incorporation by magnetron sputtering, this work is clearly a progress on the strategy to develop a new generation of dental implants.

The increased oxygen content in tantalum leads to decreased bioactivity and osteogenic ability of tantalum implants

Tantalum (Ta) implants fabricated by current processing techniques inevitably contain more or less oxygen impurities due to the extremely high melting point and high affinity of oxygen for Ta. Therefore, in this study we investigated whether oxygen impurities cause any effects on the bioactivity of Ta. EDS analysis demonstrated the surface oxygen content difference among different fabricated Ta samples, and the surface water contact angle (WCA) of Ta with high oxygen content (HO-Ta) was significantly higher than that of Ta with medium (MO-Ta) and low (LO-Ta) oxygen content. The in vitro cellular experiments showed that MC3T3-E1 cells on Ta with lower oxygen content exhibited better adhesion, growth, morphological development and in vitro osteogenic ability. Similarly, the in vivo animal experiments indicated the better bone regeneration and ingrowth performances of Ta with lower oxygen content. In addition, the highest ROS production was detected in the HO-Ta group, while the lowest in the LO-Ta group. This study suggests that the oxygen content within Ta, which occurs unavoidably due to technical limitations, negatively affects the bioactivity of Ta in a dose-dependent manner, indicating the need to develop techniques to produce orthopedic all-Ta implants.

Cytocompatibility, stability and osteogenic activity of powder metallurgy Ta-xZr alloys as dental implant materials

Tantalum (Ta) and zirconium (Zr) alloys were found to had low elastic modulus and similar biomechanical characteristics as the human bone. However, the biocompatibility and osteogenic potential of Ta-xZr alloyswith different proportions (20, 30, 40 and 50% Zr by atom) remains to be investigated. In this study, the biocompatibility of Ta-xZr alloys and commercially pure titanium (cpTi) was evaluated in vitro by cell counting kit-8 assay. The adhesion of MG63 osteoblasts to the surface of the alloys was observed by fluorescence microscopy, and their morphology was analyzed by scanning electron microscopy (SEM). The expressions of alkaline phosphatase (ALP), Ki67, osteocalcin (OC), collagen-I (Col-I) and Integrin β1 mRNA in the cultured cells were determined by RT-PCR. As a result, Ta-xZr (x = 20, 30, 40 and 50 at%) alloys were non-toxic and supported proliferation of the MG63 cells. The osteoblasts adhered to the Ta-xZr alloys, and subsequently spread and proliferated rapidly. Furthermore, the cells grown on Ta-20Zr and Ta-30Zr expressed high levels of ALP, Col I and OC, indicating that the Ta-xZr alloys can induce osteogenesis. In conclusion, Ta-xZr alloys promoted the adhesion, proliferation and osteogenic differentiation of MG63 cells. The Ta-xZr composites with a higher proportion of Ta exhibited superior osteogenic activity, and Ta-30Zr is therefore a promising alternative for Ti implants.

Osteogenic differentiation of bone marrow-derived mesenchymal stem cells on anodized niobium surface

Currently, titanium and its alloys are the most used materials for biomedical applications. However, because of the high costs of these metals, new materials, such as niobium, have been researched. Niobium appears as a promising material due to its biocompatibility, and excellent corrosion resistance. In this work, anodized niobium samples were produced and characterized. Their capacity to support the osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BM-MSCs) was also tested. The anodized niobium samples were characterized by SEM, profilometry, XPS, and wettability. BM-MSCs were cultured on the samples during 14 days, and tested for cell adhesion, metabolic activity, alkaline phosphatase activity, and mineralization. Results demonstrated that anodization promotes the formation of a hydrophilic nanoporous oxide layer on the Nb surface, which can contribute to the increase in the metabolic activity, and in osteogenic differentiation of BM-MSCs, as well as to the extracellular matrix mineralization.

Direct comparison of additively manufactured porous titanium and tantalum implants towards in vivo osseointegration

Material properties of implants such as volume porosity and nanoscale surface modification have been shown to enhance cell-material interactions in vitro and osseointegration in vivo. Porous tantalum (Ta) and titanium (Ti) coatings are widely used for non-cemented implants, which are fabricated using different processing routes. In recent years, some of those implants are being manufactured using additive manufacturing. However, limited knowledge is available on direct comparison of additively manufactured porous Ta and Ti structures towards early stage osseointegration. In this study, we have fabricated porous Ta and Ti6Al4V (Ti64) implants using laser engineered net shaping (LENS™) with similar volume fraction porosity to compare the influence of surface characteristics and material chemistry on in vivo response using a rat distal femur model for 5 and 12 weeks. We have also assessed whether surface modification on Ti64 can elicit similar in vivo response as porous Ta in a rat distal femur model for 5 and 12 weeks. The harvested implants were histologically analyzed for osteoid surface per bone surface. Field emission scanning electron microscopy (FESEM) was done to assess the bone-implant interface. The results presented here indicate comparable performance of porous Ta and surface modified porous Ti64 implants towards early stage osseointegration at 5 weeks post implantation through seamless bone-material interlocking. However, a continued and extended efficacy of porous Ta is found in terms of higher osteoid formation at 12 weeks post-surgery.

Comparison of 3D-printed porous tantalum and titanium scaffolds on osteointegration and osteogenesis

Metals such as Ta (tantalum) and Ti (titanium) have been popularly used as a bone substitute or implants in orthopedic surgery and dentistry, since they have excellent corrosion. For manufacturing porous implants with precise structure, SLM (Selective laser melting), which is one of the 3D (three-dimensional) printing techniques, is always be chosen. To compare biological performances between porous Ta and Ti implants, we designed them with the same porosity, pore shape, pore size, and pore distribution via CAD (computer aided design), and then produced them by SLM. It was shown that the equivalent stress of porous Ta and Ti were 393.62 ± 1.39 MPa and 139.75 ± 14.50 MPa, and their Young's modulus were 3.10 ± 0.03GPa and 5.42 ± 0.07GPa, respectively. Meanwhile, we investigated their biological performance with hBMMSCs (human Bone marrow mesenchymal stem cells) in vitro. The results revealed that both two scaffolds were in favor of hBMMSCs proliferation and osteogenic differentiation. In addition, porous scaffolds were implanted in the femur bone defects rabbits in vivo showed the both porous scaffolds were beneficial to the bone ingrowth and bone-implant fixation. In summary, porous Ta has an equivalent biological performance as traditional porous Ti implants in small bone defect repair. Taken together, porous Ta is a promising material for bone regeneration.

A review of materials for managing bone loss in revision total knee arthroplasty

In 2014-2015, 61,421 total knee arthroplasties (TKAs) were performed in Canada; an increase of about 20% over 2000-2001. Revision total knee arthroplasties (rTKAs) accounted for 6.8% of TKAs performed between 2014 and 2015, and this is estimated to grow another 12% by 2025. rTKAs are typically more complicated than primary TKAs due to the significant loss of femoral and tibial bone stock. The escalating demand and limitations associated with total knee arthroplasty and their revision drives the development of novel treatments. A variety of materials have been utilized to facilitate regeneration of healthy bone around the site of a knee arthroplasty. The selection of these materials is based on the bone defect size and includes bone grafts, graft substitutes and cements. However, all these materials have certain disadvantages such as blood loss, disease transmission (bone grafts), inflammatory response, insufficient mechanical properties (bone graft substitutes) thermal necrosis and stress shielding (bone cement). Recently, the use of metal augments for large bone defects has attracted attention, however they can undergo fretting, corrosion, and stress shielding. All things considered, this review indicates the necessity of developing augments that have structural integrities and biodegradation rates similar to that of human bone. Therefore, the future of bone loss management may lie in fabricating novel bioactive glass augments as they can promote bone healing and implant stability and can degrade with time.

A comparatively study of menaquinone-7 isolated from Cheonggukjang with vitamin K1 and menaquinone-4 on osteoblastic cells differentiation and mineralization

The effect of menaquinone-7 isolated from cheonggukjang was comparatively investigated with vitamin K₁ and menaquinone-4 on cell differentiation and mineralization of the osteoblastic cell line MC3T3-E1. Results indicated that all vitamin K species significantly increased MC3T3-E1 cell proliferation, cellular alkaline phosphatase activity, osteocalcin synthesis, and calcium deposition in a dose-dependent manner. Menaquinone-4 and menaquinone-7 had more potent effects on calcium deposition than vitamin K₁, and their effects were only partly reduced by warfarin (γ-carboxylation inhibitor) treatment, while warfarin abolished the induction activity of vitamin K₁ on calcification. This suggests that vitamin K₁ and K₂ (menaquinone-4 & menaquinone-7) may have different mechanisms in stimulating osteoblast mineralization. In addition, the mRNA expression ratio of osteoprotegerin and the receptor activator of nuclear factor-kB ligand was also dramatically increased by treatment with vitamin K₁ (62%), menaquinone-4 (247%), and menaquinone-7 (329%), suggesting that vitamin K may suppress the formation of osteoclast by up-regulating the ratio of osteoprotegerin/receptor activator of nuclear factor-kB ligand in osteoblasts. These results provide compelling evidence that vitamin K₁, menaquinone-4, and menaquinone-7 all can promote bone health, which might be associated with elevations in the osteoprotegerin/receptor activator of nuclear factor-kB ligand ratio.

Advanced antibacterial activity of biocompatible tantalum nanofilm via enhanced local innate immunity

Tantalum (Ta) has been shown to enhance osseointegration in clinical practice, yet little is known about whether Ta nanofilms can be used as antimicrobial coatings in vivo. A highly biocompatible Ta nanofilm was developed using magnetron sputtering technology to further study the mechanism of its antibacterial effects in vivo and elucidate its potential for clinical translation. The Ta nanofilms exhibited effective antimicrobial activity against soft tissue infections but did not show an intrinsic antimicrobial effect in vitro. This inconsistency between the in vivo and in vitro antimicrobial effects was further investigated using ex vivo models. The Ta nanofilms could enhance the phagocytosis of bacteria by polymorphonuclear neutrophils (PMNs, neutrophils), reduce the lysis of neutrophils and enhance the proinflammatory cytokine release of macrophages. This accumulative enhancement of the local host defenses contributed to the favorable antibacterial effect in vivo. The alleviated osteolysis observed in the presence of the Ta nanofilms in the osteomyelitis model further proved the practicality of this antibacterial strategy in the orthopedic field. In summary, Ta nanofilms show excellent biocompatibility and in vivo antimicrobial activity mediated by the enhancement of local innate immunity and are promising for clinical application. STATEMENT OF SIGNIFICANCE: In this study, Ta nanofilms were deposited on titanium substrate by magnetron sputtering. Ta nanofilms exhibited excellent in vivo and in vitro biocompatibility. In vivo antimicrobial effects of Ta nanofilms were revealed by soft tissue infection and osteomyelitis models, while no direct antibacterial activity was observed in vitro. Comprehensive ex vivo models revealed that Ta nanofilms could enhance the phagocytosis of bacteria by neutrophils, reduce the lysis of neutrophils and promote the release of proinflammatory cytokines from macrophages. This immunomodulatory effect helps host to eliminate bacteria. In contrast to traditional antimicrobial nanocoatings which apply toxic materials to kill bacteria, this work proposes a safe, practical and effective Ta nanofilm immunomodulatory antimicrobial strategy with clinical translational prospect.

Mesenchymal stem cell-loaded porous tantalum integrated with biomimetic 3D collagen-based scaffold to repair large osteochondral defects in goats

Background

The body is unable to repair and regenerate large area bone defects. Moreover, the repair capacity of articular cartilage is very limited. There has long been a lack of effective treatments for osteochondral lesions. The engineered tissue with biphase synthetic for osteochondral repair has become one of the hot research fields over the past few years. In this study, an integrated biomanufacturing platform was constructed with bone marrow mesenchymal stem cells (BMSCs)/porous tantalum (pTa) associated with chondrocytes/collagen membranes (CM) to repair large osteochondral defects in load-bearing areas of goats.

Methods

Twenty-four goats with a large osteochondral defect in the femoral heads of the left hind legs were randomly divided into three groups: eight were treated with chondrocytes/CM-BMSCs/pTa, eight were treated with pure CM-pTa composite, and the other eight goats were untreated. The repair effect was assessed by X-ray, gross observation, and histomorphology for 16 weeks after the operation. In addition, the biocompatibility of chondrocytes/CM-BMSCs/pTa was observed by flow cytometry, CCK8, immunocytochemistry, and Q-PCR. The characteristics of the chondrocytes/CM-BMSCs/pTa were evaluated using both scanning electron microscopy and mechanical testing machine.

Results

The integrated repair material consists of pTa, injectable fibrin sealant, and CM promoted adhesion and growth of BMSCs and chondrocytes. pTa played an important role in promoting the differentiation of BMSCs into osteoblasts. Three-dimensional CM maintained the phenotype of chondrocytes successfully and expressed chondrogenic genes highly. The in vivo study showed that after 16 weeks from implantation, osteochondral defects in almost half of the femoral heads had been successfully repaired by BMSC-loaded pTa associated with biomimetic 3D collagen-based scaffold.

Conclusions

The chondrocytes/CM-BMSCs/pTa demonstrated significant therapeutic efficacy in goat models of large osteochondral defect. This provides a novel therapeutic strategy for large osteochondral lesions in load-bearing areas caused by severe injury, necrosis, infection, degeneration, and tumor resection with a high profile of safety, effectiveness, and simplicity.

Nanolamellar Tantalum Interfaces in the Osteoblast Adhesion

The design of topographically patterned surfaces is considered to be a preferable approach for influencing cellular behavior in a controllable manner, in particular to improve the osteogenic ability of bone regeneration. In this study, we fabricated nanolamellar tantalum (Ta) surfaces with lamellar wall thicknesses of 40 and 70 nm. The cells attached to nanolamellar Ta surfaces exhibited higher protein adsorption and expression of β1 integrin, as compared to the nonstructured bulk Ta, which facilitated the initial cell attachment and spreading. We thus, as expected, observed significantly enhanced osteoblast adhesion, growth, and alkaline phosphatase activity on nanolamellar Ta surfaces. However, the beneficial effects of nanolamellar structures on osteogenesis became weaker as the lamellar wall thickness increased. The interaction between cells and Ta surfaces was examined through adhesion forces using atomic force microscopy. Our findings indicated that the Ta surface with a lamellar wall thickness of 40 nm exhibited the strongest stimulatory effect. The observed strongest adhesion force between the cell-attached tip and the Ta surface with a 40 nm thick lamellar wall encouraged the much stronger binding of cells with the surface and thus well-attached, -stretched, and -grown cells. We attributed this to the increase in the available contact area of cells with the thinner nanolamellar Ta surface. The increased contact area allowed the enhancement of the cell surface interaction strength and, thus, improved osteoblast adhesion. This study suggests that the thin nanolamellar topography shows immense potential in improving the clinical performance of dental and orthopedic implants.

Addressing large tibial osseous defects in primary total knee arthroplasty using porous tantalum cones

BACKGROUND

Tibial osseous defects can present a serious challenge in primary total knee arthroplasty. We describe a technique of using porous tantalum cones along with primary arthroplasty implants to address large tibial osseous defects in primary total knee arthroplasty and present the short-term results.

METHODS

We present 17 cases (15 patients) in which primary total knee implants and porous tantalum cones were used to address large tibial bony defects. Clinical results were evaluated using Knee Society Scores, pre- and postoperative knee range of motion, and serial radiographs.

RESULTS

At an average of 3.5 years of follow-up, all 17 knees had functioning implants with stable metaphyseal cones demonstrating radiographic evidence of osteointegration. At a minimum follow-up of two years, no patient had signs of osteolysis, instability, infection, or systemic complications. All 15 patients had excellent results with an average post-operative Knee Society Score of 94.6. Knee flexion improved by an average of 12.0° and knee extension improved to neutral in all patients.

CONCLUSION

Primary total knee arthroplasty with porous tantalum cone augmentation produced excellent short-term results and should be considered an effective method for addressing large tibial osseous defects in primary total knee arthroplasty.

The Use of Tantalum Metaphyseal Cones for the Management of Severe Bone Defects in Septic Knee Revision

BACKGROUND

Femoral and tibial massive bone defects are common findings in septic total knee revision and pose considerable challenges for the orthopedic surgeon. The aim of this study was to report the midterm clinical and radiographic outcomes with the use of tantalum cones for the management of massive bone defects after 2-stage knee revision.

METHODS

We retrospectively reviewed the medical records of 60 patients (mean age, 67.9 ± 8.8 years) treated with 94 tantalum cones associated with constrained or semiconstrained knee for massive bone loss (mean follow-up, 43.5 ± 17.4 months). In all cases, the indication was a staged revision for periprosthetic knee infection. Functional scores, radiographic outcomes, and implant survivorship were analyzed.

RESULTS

The mean Knee Society Score and Oxford Knee Score improved from 44.1 ± 7.4 and 19.2 ± 4.1 to 85.4 ± 5.6 and 38.4 ± 3.9 (P < .01), respectively. The mean flexion increased from 60.6° ± 15.5° to 96.8° ± 10.9° at the last evaluation (P < .01). The mean improvement in flexion contracture was 6.2 ± 8.0 (P < .01). Two failures (3.3%) due to periprosthetic knee infection recurrence were observed, but no cone-related mechanical failures were reported. The cone-related survival rate was 97.8%.

CONCLUSION

Excellent clinical and radiographic midterm outcomes were achieved with a low complication rate. Tantalum cones may be considered a safe and effective option in the management of massive bone defects also in septic knee revision surgery.

Can tibial tantalum cones eventually eliminate the adjuvant use of metallic augments for AORI type 2B/3 metaphyseal defects??-A novel surgical technique and case series

BACKGROUND

For extensive metaphyseal defects, the use of tantalum cones is usually combined with adjuvant stems which may be cemented/cementless and metallic bone augments for additional stability. A Tibial baseplate-Cone construct with proud tibial cones and without metallic augments has been described for AORI type 2B/3 tibial defects.

METHODS

A case series analysis of 6 patients with AORI type 3 defects treated with unstepped proud Tantalum tibial metaphyseal cones without metallic wedges/full width augments. A follow-up analysis done with clinico-radiographic interpretation.

RESULTS

100% osteointegration noted in final radiographs of all patients at an average follow-up of 4.1 years. Preoperative average ROM/KSS of 75/49 improved to postoperative ROM/KSS of 104/79. Outcomes were interpreted as excellent in 50% of cases and good in the remaining 50%.

CONCLUSION

The "Tibial base plate-cone without augments (BCCA)"type of a construct may offer a valid long term advantage over the Tibial base plate-Augment-Cone combination in massive tibial bone defects. Simply building up the tantalum cone to the native joint line position by increasing cone height can exclude use of augments or wedges.

Osteolysis Complicating Total Knee Arthroplasty

Osteolysis is a process mounted by the host immune system that relies on several variables, including patient-related factors, type of insert material, modes of wear, and implant design. Imaging techniques such as radiography, computed tomography (CT) scans, magnetic resonance imaging (MRI), and tomosynthesis aid in diagnosing osteolysis. Surgical options for the treatment of osteolysis include the insertion of bone grafts, bone cement, and prosthetic augmentation. Although no approved pharmacological therapies for the specific treatment of osteolysis exist, the use of bisphosphonates and statins decreases the risk of osteolysis.

Analysis of Tantalum Implants used for Avascular Necrosis of the Femoral Head: A Review of Five Retrieved Specimens

Aim

The effective results shown in the porous systems of tantalum employed for the use of osseointegrates has been demonstrated by means of animal experimentation. However, there is a total lack of any research studies on the osseointegration of tantalum implants from retrieval of the same after a period of time whereby the material had been implanted within the human body.

Materials and Methods

For this study, five rod implants used for the treatment of avascular necrosis of the femoral head were retrieved following collapse of the femoral head and conversion to total hip arthroplasty. The time of implantation ranged between six weeks and twenty months.

Results

Observation during this study has confirmed the effectiveness of osseointegration within this period of time. New bone was observed around and within the porous system of the on rod devices at retrieval date. The bone ingrowth, however, proved to be slower and less intense than that resulting within animal species during the first few months after implantation.

Conclusions

The results obtained in the quantitative assessment of this process proved to be similar to those results achieved by other authors in previous experimental work studies.

Evaluation of an artificial vertebral body fabricated by a tantalum-coated porous titanium scaffold for lumbar vertebral defect repair in rabbits

Tantalum (Ta)-coated porous Ti-6A1-4V scaffolds have better bioactivity than Ti-6A1-4V scaffolds; however, their bioperformance as an artificial vertebral body (AVB) is unknown. In the present study, we combined a Ta-coated Ti-6A1-4V scaffold with rabbit bone marrow stromal cells (BMSCs) for tissue-engineered AVB (TEAVB) construction and evaluated the healing and fusion efficacy of this scaffold in lumbar vertebral defects after corpectomy in rabbits. The results showed that BMSCs on the surface of the Ta-coated Ti scaffolds proliferated better than BMSCs on Ti scaffolds. Histomorphometry showed better bone formation when using Ta-coated TEAVBs than that with Ti TEAVBs at both 8 and 12 weeks after implantation. In addition, the vertical and rotational stiffness results showed that, compared with uncoated TEAVBs, Ta-coated TEAVBs enhanced rabbit lumbar vertebral defect repair. Our findings demonstrate that Ta-coated TEAVBs have better healing and fusion efficacy than Ti TEAVBs in rabbit lumbar vertebral defects, which indicates their good prospects for clinical application.

Cytocompatible tantalum films on Ti6Al4V substrate by filtered cathodic vacuum arc deposition

Tantalum films were deposited on negatively biased Ti6Al4V substrates using filtered cathodic vacuum arc deposition to enhance the corrosion resistance of the Ti6Al4V alloy. The effect of substrate voltage bias on the microstructure, mechanical and corrosion properties was examined and the cytocompatibility of the deposited films was verified with mammalian cell culturing. The Ta films deposited with substrate bias of -100V and -200V show a mixture of predominantly β phase and minority of α phase. The Ta/-100V film shows adhesive failure at the Ti/Ta interface and a cohesive fracture is observed in Ta/-200V film. The Ta/-100V showed a significant improvement in corrosion resistance, which is attributed to the stable oxide layer. The in-vitro cytocompatibility of the materials was investigated using rat bone mesenchymal stem cells, and the results show that the Ta films have no adverse effect on mammalian cell adhesion and spreading proliferation.

Application of combined porous tantalum scaffolds loaded with bone morphogenetic protein 7 to repair of osteochondral defect in rabbits<sup/>

PURPOSE

Porous tantalum (PT) has been widely used in orthopaedic applications for low modulus of elasticity, excellent biocompatibility, and the microstructures similar to cancellous bone. In order to improve the biological activity of PT, biologically active factors can be combined with the material. The purpose of this study was to investigate if bone morphogenetic protein 7 (BMP-7) modifications could enhance the repairing of cartilage of PT in osteochondral defect in medial femoral condyle of rabbits.

METHODS

A cylindrical osteochondral defect model was created on the animal medial femoral condyle of and filled as follows: PT modified with BMP-7 for MPT group, non-modified PT for the PT group, while no implants were used for the blank group. The regenerated osteochondral tissue was assessed and analyzed by histological observations at four, eight and 16 weeks post-operation and evaluated in an independent and blinded manner by five different observers using a histological score. Osteochondral and subchondral bone defect repair was assessed by micro-CT scan at 16 weeks post-operation, while the biomechanical test was performed at 16 weeks post-operation.

RESULTS

Briefly, higher overall histological score was observed in the MPT group compared to PT group. Furthermore, more new osteochondral tissue and bone formed at the interface and inside the inner pores of scaffolds of the MPT group compared to PT group. Additionally, the micro-CT data suggested that the new bone volume fractions and the quantity and quality of trabecular bone, as well as the maximum release force of the bone, were higher in the MPT group compared to PT group.

CONCLUSIONS

We demonstrated that the applied modified PT with BMP-7 promotes excellent subchondral bone regeneration and may serve as a novel approach for osteochondral defects repair.

Do Porous Tantalum Metaphyseal Cones Improve Outcomes in Revision Total Knee Arthroplasty?

BACKGROUND

Some authors have advocated for use of porous tantalum metaphyseal cones to manage bone defects during revision total knee arthroplasty (TKA). The purpose of this study is to compare results with porous metaphyseal cones to results with traditional hybrid stem fixation in revision TKA.

METHODS

Forty-nine patients undergoing revision TKA with femoral and/or tibial metaphyseal cones (39 tibial only, 3 femoral only, 7 both) were matched by surgical indication to 49 patients undergoing revision TKA with a traditional hybrid stem (non-cone) technique. Clinical and radiographic outcomes were compared at a minimum of two-year follow-up (mean 3.5 years) with adjustment for baseline characteristics.

RESULTS

Pre-revision bone defects and most baseline demographics were similar between the cone and non-cone cohorts suggesting appropriate matching. Patients in the non-cone cohort had greater pre- to post-operative increases in Knee Society Score (37.2 ± 18.6 vs 28.4 ± 17.8, P = .010) and Knee Society Functional Score (30.4 ± 24.3 vs 13.1 ± 27.6, P = .003). The cohorts did not differ with respect to complications, subsequent reoperation, subsequent revision, patient satisfaction, tibial overhang, the presence of radio-sclerotic lines, cortical hypertrophy around the stems, or tibial subsidence.

CONCLUSION

In this series, metaphyseal cones were not associated with superior outcomes at short-term follow-up. Given the increased cost associated with use of cones compared to traditional techniques, this study cannot support the routine use of metaphyseal cones in revision TKA. Longer-term follow-up will be necessary to determine if construct durability differs over the long term.

Enhanced Biocompatibility in Anodic TaO x Nanotube Arrays

This study first investigates the biocompatibility of self-organized TaO x nanotube arrays with different nanotube diameters fabricated by electrochemical anodization. All as-anodized TaO x nanotubes were identified to be an amorphous phase. The transition in surface wettability with TaO x nanotube diameters can be explained based on Wenzel's model in terms of geometric roughness. In vitro biocompatibility evaluation further indicates that fibroblast cells exhibit an obvious wettability-dependent behavior on the TaO x nanotubes. The 35-nm-diameter TaO x nanotube arrays reveal the highest biocompatibility among all samples. This enhancement could be attributed to highly dense focal points provided by TaO x nanotubes due to higher surface hydrophilicity. This work demonstrates that the biocompatibility in Ta can be improved by forming TaO x nanotube arrays on the surface with appropriate nanotube diameter and geometric roughness.

Initial Stability of Cemented vs Cementless Tibial Components Under Cyclic Load

BACKGROUND

Cement fixation of total knee components remains the gold standard despite resurgence in cementless fixation with the goal of long-term durable fixation. Initial stability is paramount to achieve bony ingrowth of cementless components.

METHODS

Twelve cemented and cementless tibial baseplates were implanted into sawbones and tested using a physiological medial-lateral load distribution for 10,000 cycles to represent 8 weeks of in vivo function. Micromotion was measured at 5 locations around the baseplate during loading.

RESULTS

Cycling had a significant effect on the change in micromotion between maximum and minimum loads at the anterior, medial, lateral, posteromedial, and posterolateral tray edge locations. A significant effect of fixation technique was detected for the anterior (P < .001), medial (P = .002), and lateral (P = .0056) locations but not for the posteromedial (P = .36) or posterolateral (P = .82) locations. Differences in micromotion between cemented and cementless components did not exceed 150 μm at any tested location.

CONCLUSION

The micromotion experienced by cementless tibial components in the present study may indicate a lower initial mechanical stability than the cemented group. However, this difference in initial stability may be subclinical because the differences between average cemented and cementless micromotion were <150 μm at all measured locations under the loading regime implemented.

Antibacterial activity, corrosion resistance and wear behavior of spark plasma sintered Ta-5Cu alloy for biomedical applications

Tantalum has been widely used in orthopedic and dental implants. However, the major barrier to the extended use of such medical devices is the possibility of bacterial adhesion to the implant surface which will cause implant-associated infections. To solve this problem, bulk Ta-5Cu alloy has been fabricated by a combination of mechanical alloying and spark plasma sintering. The effect of the addition of Cu on the hardness, antibacterial activity, cytocompatibility, corrosion resistance and wear performance was systematically investigated. The sintered Ta-5Cu alloy shows enhanced antibacterial activity against E. Coli due to the sustained release of Cu ions. However, the addition of Cu would produce slight cytotoxicity and decrease corrosion resistance of Ta. Furthermore, pin-on-disk wear tests show that Ta-5Cu alloy has a much lower coefficient of friction but a higher wear rate and shows a distinct wear mode from that of Ta upon sliding against stainless steel 440C. Wear-induced plastic deformation leads to elongation of Ta and Cu grains along the sliding direction and nanolayered structures were observed upon approaching the sliding surface. The presence of hard oxides also shows a profound effect on the plastic flow of the base material and results in localized vortex patterns. The obtained results are expected to provide deep insights into the development of novel Ta-Cu alloy for biomedical applications.

Significantly enhanced osteoblast response to nano-grained pure tantalum

Tantalum (Ta) metal is receiving increasing interest as biomaterial for load-bearing orthopedic applications and the synthetic properties of Ta can be tailored by altering its grain structures. This study evaluates the capability of sliding friction treatment (SFT) technique to modulate the comprehensive performances of pure Ta. Specifically, novel nanocrystalline (NC) surface with extremely small grains (average grain size of ≤20 nm) was fabricated on conventional coarse-grained (CG) Ta by SFT. It shows that NC surface possessed higher surface hydrophilicity and enhanced corrosion resistance than CG surface. Additionally, the NC surface adsorbed a notably higher percentage of protein as compared to CG surface. The in vitro results indicated that in the initial culture stages (up to 24 h), the NC surface exhibited considerably enhanced osteoblast adherence and spreading, consistent with demonstrated superior hydrophilicity on NC surface. Furthermore, within the 14 days culture period, NC Ta surface exhibited a remarkable enhancement in osteoblast cell proliferation, maturation and mineralization as compared to CG surface. Ultimately, the improved osteoblast functions together with the good mechanical and anti-corrosion properties render the SFT-processed Ta a promising alternative for the load-bearing bone implant applications.

Enhanced osteointegration of tantalum-modified titanium implants with micro/nano-topography

Ta modification enhanced the osteointegration of an SLA surface with micro/nano topography and the possible mechanism might be activation of the Wnt pathway.

Tantalum nitride coatings prepared by magnetron sputtering to improve the bioactivity and osteogenic activity for titanium alloy implants

TaN film has a positive effect on the biocompatibility and osteoinductive ability of Ti6Al4V-based implants.

Involvement of autophagy in tantalum nanoparticle-induced osteoblast proliferation

Porous tantalum (Ta) implants are highly corrosion resistant and biocompatible, and they possess significantly better initial stability than that of conventional titanium (Ti) implants. During loading wear, Ta nanoparticles (Ta-NPs) that were deposited on the surface of a porous Ta implant are inevitably released and come into direct contact with peri-implant osteoblasts. The wear debris may influence cell behavior and implant stabilization. However, the interaction of Ta-NPs with osteoblasts has not been clearly investigated. This study aimed to investigate the effect of Ta-NPs on cell proliferation and their underlying mechanism. The Cell Counting Kit-8 (CCK-8) assay was used to measure the cell viability of MC3T3-E1 mouse osteoblasts and showed that Ta-NP treatment could increase cell viability. Then, confocal microscopy, Western blotting, and transmission electron microscopy were used to confirm the autophagy induced by Ta-NPs, and evidence of autophagy induction was observed as positive LC3 puncta, high-LC3-II expression, and autophagic vesicle ultrastructures. The CCK-8 assay revealed that the cell viability was further increased and decreased by the application of an autophagy inducer and inhibitor, respectively. In addition, pre-treatment with autophagy inhibitor 3-methyladenine (3-MA) inhibited the Ta-NP-induced autophagy. These results indicate that the Ta-NPs can promote cell proliferation, that an autophagy inducer can further strengthen this effect and that an autophagy inhibitor can weaken this effect. In conclusion, autophagy was involved in Ta-NP-induced cell proliferation and had a promoting effect.

Effects of nano tantalum implants on inducing osteoblast proliferation and differentiation

In the present study, we examined the effects of nano tantalum (Ta) dental implants on inducing osteoblast proliferation and differentiation. The MG-63 osteoblasts were divided into 3 groups after recovery, passage and storage: i) Osteoblast culturing group (control group); ii) osteoblast and titanium (Ti) implant co-culturing group (Ti group); and iii) osteoblast and Ta implant co-culturing group (Ta group). After 7 days, a scanning electron microscope was used to observe the growth status, number and morphological changes of the cells on the surfaces of the materials. An MTT assay was used to detect cell proliferation after culturing for 1, 3 and 7 days. ELISA assay was used to detect the levels of alkaline phosphatase (ALP) after 1, 3 and 7 days. Western blot analysis was used to detect the expression levels of collagen type I (Col-1) and osteocalcin after 1, 3 and 7 days. There was significant cell spreading on the surfaces of Ti and of Ta after 7 days, flat and with many pseudopodia. Additionally, there were more cell components in the Ta group. Concurrently, cell proliferation in the Ti and Ta groups increased. There was also an increase in the level of ALP and the expression level of Col-1 over time. The indexes of the Ta group were more apparent than those of the Ti group at each time-point, and the differences were statistically significant (p<0.05). In conclusion, compared with Ti implants, Ta implants induced more osteoblast proliferation and differentiation.

Midterm Results of Porous Tantalum Femoral Cones in Revision Total Knee Arthroplasty

BACKGROUND

Severe bone loss during a revision total knee arthroplasty (TKA) remains a challenging problem. The purpose of this study was to determine the midterm clinical outcomes, fixation as evaluated radiographically, and survivorship of tantalum femoral cones used during revision TKAs in patients with severe femoral bone loss.

METHODS

From 2003 to 2011, 159 tantalum metaphyseal femoral cones were implanted in 157 patients at a single institution. Knee Society scores, radiographic results, and implant survivorship were analyzed. Two patients were lost to follow-up. Nineteen died of causes unrelated to the surgery but had been followed for >2 years and thus were included in the study. The mean age at the time of the index surgery was 64 years, and 82 patients were male. The mean duration of follow-up was 5 years (range, 2 to 10 years).

RESULTS

The mean Knee Society score increased from 47 preoperatively to 65 at the most recent follow-up evaluation (p = 0.1). Radiographically, all 134 unrevised femoral cones were seen to be well fixed without any evidence of loosening. At 5 years, 23 cones had been revised: 14 because of infection, 6 because of aseptic loosening of the cone (all in hinged TKAs in patients with a Type-3 defect), and 3 because of ligamentous instability. The 5-year survivorship was 96% when the end point was revision of the cone due to aseptic loosening, 84% when it was revision of the cone for any reason, and 70% when it was any reoperation.

CONCLUSIONS

In what we believe to be the largest series of such implants, femoral cones provided a durable and reliable option for metaphyseal fixation during revision TKA with severe femoral bone loss. Aseptic failure of the femoral cone was associated with use of a hinged TKA in a patient with a Type-3 bone defect.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Osteogenic potential of human adipose-tissue-derived mesenchymal stromal cells cultured on 3D-printed porous structured titanium

Integration of porous metal prosthetics, which restore form and function of irreversibly damaged joints, into remaining healthy bone is critical for implant success. We investigated the biological properties of adipose-tissue-derived mesenchymal stromal/stem cells (AMSCs) and addressed their potential to alter the in vitro microenvironment of implants. We employed human AMSCs as a practical source for musculoskeletal applications because these cells can be obtained in large quantities, are multipotent, and have trophic paracrine functions. AMSCs were cultured on surgical-grade porous titanium disks as a model for orthopedic implants. We monitored cell/substrate attachment, cell proliferation, multipotency, and differentiation phenotypes of AMSCs upon osteogenic induction. High-resolution scanning electron microscopy and histology revealed that AMSCs adhere to the porous metallic surface. Compared to standard tissue culture plastic, AMSCs grown in the porous titanium microenvironment showed differences in temporal expression for genes involved in cell cycle progression (CCNB2, HIST2H4), extracellular matrix production (COL1A1, COL3A1), mesenchymal lineage identity (ACTA2, CD248, CD44), osteoblastic transcription factors (DLX3, DLX5, ID3), and epigenetic regulators (EZH1, EZH2). We conclude that metal orthopedic implants can be effectively seeded with clinical-grade stem/stromal cells to create a pre-conditioned implant.

Tantalum coating of porous carbon scaffold supplemented with autologous bone marrow stromal stem cells for bone regeneration in vitro and in vivo

Porous tantalum metal with low elastic modulus is similar to cancellous bone. Reticulated vitreous carbon (RVC) can provide three-dimensional pore structure and serves as the ideal scaffold of tantalum coating. In this study, the biocompatibility of domestic porous tantalum was first successfully tested with bone marrow stromal stem cells (BMSCs) in vitro and for bone tissue repair in vivo. We evaluated cytotoxicity of RVC scaffold and tantalum coating using BMSCs. The morphology, adhesion, and proliferation of BMSCs were observed via laser scanning confocal microscope and scanning electron microscopy. In addition, porous tantalum rods with or without autologous BMSCs were implanted on hind legs in dogs, respectively. The osteogenic potential was observed by hard tissue slice examination. At three weeks and six weeks following implantation, new osteoblasts and new bone were observed at the tantalum-host bone interface and pores. At 12 weeks postporous tantalum with autologous BMSCs implantation, regenerated trabecular equivalent to mature bone was found in the pore of tantalum rods. Our results suggested that domestic porous tantalum had excellent biocompatibility and could promote new bone formation in vivo. Meanwhile, the osteogenesis of porous tantalum associated with autologous BMSCs was more excellent than only tantalum implantation. Future clinical studies are warranted to verify the clinical efficacy of combined implantation of this domestic porous tantalum associated with autologous BMSCs implantation and compare their efficacy with conventional autologous bone grafting carrying blood vessel in patients needing bone repairing.

Current evidence and future directions for research into the use of tantalum in soft tissue re-attachment surgery

The use of tantalum is well established in orthopaedic surgery.