Physical, morphological and bioactive properties of Co-Cr-W-Ta alloys: Influence of insertion of tantalum and surface thermochemical treatment on bioactivity.

The development of bioactivity in bioinert metallic alloys is a field of interest aiming to improve some aspects of these materials for implant applications. New Co63 Cr28 W9-x Tax alloys with different Ta concentrations (x = 0, 2, 4, 6, and 9% w/w) were synthesized in the work reported here. The alloys were characterized by x-ray diffraction, volumetric density, Vickers microhardness, atomic force microscopy, scanning electron microscopy (SEM), and energy-dispersion x-ray spectroscopy (EDS). Bioactivity properties were evaluated by in vitro tests with simulated body fluid (SBF). In vivo assays were performed to assess biocompatibility. The influence of surface thermochemical treatment and Ta insertion on the bioactive properties of the alloys was investigated. The results showed that the alloy structure comprises εCo and αCo phases, with cobalt as a matrix with Cr, W, and Ta as a solid solution. TaCo2 phase is observed in the alloys with 4, 6, and 9% w/w of Ta, and its amount increase as Ta concentration increases. Volumetric density is reduced (from 8.78 ± 0.06 to 8.56 ± 0.09 g/cm3 ) as Ta concentration increases (from 0% to 9% w/w) mainly due to the lower density of the tantalum compared to the tungsten metal. On the other hand, the TaCo2 phase contributes to the increase of Vickers's hardness by ~17.6% for the alloy with 9% Ta (394.7 ± 8.1 HV) compared with Co63 Cr28 W9 (336 ± 5 HV). The topographic analysis showed increased roughness and adhesion due to the nucleation of Ta1.1 O1.05 and Ca2 Ta2 O7 crystals after surface thermochemical treatment. The roughness and adhesion increase from 16.9 ± 0.6 nm and 8.3 ± 1.8 nN (untreated surface) to 255.7 ± 17.7 nm and 24.1 ± 12.6 nN (treated surface), respectively, for the Co63 Cr28 Ta9 alloy. These results suggest that thermochemical treatment provides surface conditions favorable to hydroxyapatite (HA) nucleation. The SEM and EDS data showed the nucleation of spongy structures, consistent with HA, composed mainly of Ca and P, indicating that oxides tantalum promoted a bioactive response on the sample's surface. The biological assay corroborated the alloy's safety and applicability, highlighting its potential in biomedical application since no harmful effects were observed.

Midterm Radiographic Results and Reoperations of Tantalum Trabecular Metal Cones in Knee Arthroplasties / Reoperações e resultados radiográficos de médio prazo do uso de cone de metal trabecular de tântalo nas artroplastias do joelho

Abstract Objective The management of bone loss represents a challenge in revisions of total knee arthroplasty (rTKA) and in complex primary total knee arthroplasties (TKAs). The purpose of the present study was to evaluate the midterm outcomes (5-year minimum follow-up) of knee reconstructions with tantalum trabecular metal (TM) cones on bone defects Anderson Orthopaedics Research Institute (AORI) 2 and 3. Materials and MethodsA retrospective analysis of the medical records of patients operated on between July 2008 and November 2014 was performed, collecting the following data: age, gender, laterality, body mass index, etiology of arthrosis, comorbidities, AORI classification of bone defects, causes for revision, readmissions, reoperations, perioperative and postoperative complications, radiographic signs of osteointegration, and maintenance of the TM support. Results A total of 11 patients with a mean follow-up of 7.28 years (standard deviation [SD] = 1.88; range = 5.12-10 years) was evaluated, with 1 patient operated upon for a primary arthroplasty, 6 for revision arthroplasties, and 4 for a second revision arthroplasty (re-revision). There were complications with the surgical wound, injury to the extensor mechanism and loosening of the femoral component in three of the patients that led to the necessity of four procedures due to complications with the surgical wound, injury to the extensor mechanism and loosening of the femoral component. Radiological signs of osteointegration of the trabecular cones were observed in all patients. We did not observe migration of the TM cones or the prosthetic components in the sample. Conclusion The tantalum metaphyseal cones were able to provide efficient structural support to prosthetic implants with radiographic signs of osteointegration in the medium term.

Resumo Objetivo O manejo da perda óssea representa um grande desafio em cirurgias de revisão de artroplastia do joelho (rATJ) e em artroplastias totais do joelho (ATJ) primárias complexas. O objetivo do presente estudo foi avaliar os resultados em médio prazo (seguimento mínimo de 5 anos) das reconstruções de joelho nas quais cones de metal trabecular (MT) de tântalo foram utilizados para tratamento de defeitos ósseos tipos 2 e 3, de acordo com a classificação proposta pela Anderson Orthopaedic Research Institute (AORI). Métodos Feita análise retrospectiva dos prontuários dos pacientes operados entre julho de 2008 e novembro de 2014, coletando-se os seguintes dados: idade, gênero, lateralidade, índice de massa corporal, etiologia da artrose, comorbidade, classificação AORI da falha óssea, causa da revisão da artroplastia total do joelho, reinternações, reoperações, complicações peri- e pós-operatórias, ocorrência de osteointegração radiográfica e manutenção da função de suporte do MT. Resultados Foram avaliados 11 pacientes com tempo médio de seguimento de 7,28 anos (desvio padrão [DP] = 1,88; variação = 5,12-10 anos), sendo que 1 paciente foi submetido a artroplastia primária, 6 a artroplastia de revisão e 4 a segunda revisão de artroplastia (re-revisão). Três pacientes necessitaram de quatro reoperações devido a complicações com a ferida operatória, a lesão do mecanismo extensor e a soltura do componente femoral. Sinais de osteointegração dos cones trabeculados foram observados em todos os pacientes. Não observamos migração do cone de MT ou dos componentes protéticos. Conclusão Os cones metafisários de tântalo foram capazes de prover suporte estrutural eficiente aos implantes protéticos com sinais radiográficos de osteointegração em médio prazo.

Uso de conos de metal trabecular para defectos óseos severos en cirugía de revisión de reemplazo total de rodilla / The use of trabecular metal cones for the management of severe bone defects in revision total knee replacement

Introducción: Las alternativas reconstructivas para defectos óseos severos en la cirugía de revisión de prótesis son las camisas metafisarias, los conos de metal trabecular y el injerto óseo impactado o estructural. El objetivo del estudio fue analizar la tasa de osteointegración de los conos de metal trabecular en pacientes con cirugía de revisión de prótesis total de rodilla. El objetivo secundario fue analizar los resultados funcionales, las tasas de complicaciones y reoperaciones. Materiales y Métodos: Cohorte retrospectiva de pacientes con conos de metal trabecular colocados en la cirugía de revisión de prótesis y un seguimiento mínimo de 2 años. Se evaluaron las causas de la revisión, cirugías previas, tipo de defecto óseo, cantidad y tipo de conos utilizados, y los diseños de las prótesis. Se realizó una evaluación clínico-radiográfica, se registraron las complicaciones y las revisiones ulteriores. Resultados: Se evaluó a 35 pacientes (49 conos de metal trabecular) en forma retrospectiva, con un seguimiento promedio de 32.1 meses. La mayoría de los defectos eran tibiales AORI 3, seguidos de los femorales tipo 3. La tasa de osteointegración de los conos fue del 94%; la de complicaciones, del 20% y la de reoperaciones, del 8,5%. El KSS objetivo promedio aumentó de 39 en el preoperatorio a 71 en el último control y el puntaje de la EAV promedio fue 8 y 2,5, respectivamente. Conclusión: La excelente tasa de osteointegración (94%) y los buenos resultados clínicos posicionan a los conos de metal trabecular como una alternativa para los defectos óseos severos. Nivel de Evidencia: IV

Introduction: Major bone defects represent a challenge during revision total knee arthroplasty (TKA) and there is still considerable debate about the best therapeutic option. The purpose of this study was to retrospectively assess the osseointegration rate of trabecular metal cones in revision TKA with severe bone defects. The secondary purpose was to evaluate the functional outcomes and complication and reoperation rates. Materials and Methods: A single-center, retrospective cohort including all consecutive cases of revision TKA using trabecular metal cones. All patients with a minimum 2-year follow-up were included in the study. Reasons for revision, number of previous surgeries, type of bone defect, and number and type of trabecular cones used were evaluated. Clinical and radiological outcomes were also analyzed as well as complications rates. Results: 35 patients (49 cones) were evaluated with a mean follow-up of 32.1 months (24-62). Most defects were localized in the tibia and were classified as AORI type 3. The rate of osseointegration of the cones was 94%; the complication rate, 20%; and the reoperation rate, 8.5%. The mean KSS increased from 39 preoperatively to 71 at the last follow-up, and the mean VAS from 8 to 2.5. Conclusion: The excellent osseointegration rate (94%), added to the good clinical outcomes, position the trabecular metal cones as an alternative to treat severe bone defects. Level of Evidence: IV

Cell investigation into the biocompatibility of adult human dermal fibroblasts with PCL nanofibers/TiO2 nanotubes on the surface of Ti-30Ta alloy for biomedical applications.

The polymer poly(ε-caprolactone) (PCL) has been used in the biomaterial field for its relatively inexpensive price and suitability for modification. Also, its chemical and biological properties are desirable for biomedical applications. The electrospinning process has been used for producing polymer fibers of PCL due in large part to an increased interest in nanoscale properties and technologies. Moreover, the use of biocompatible polymers for the viability of cell growth is a promising alternative to improve osseointegration. Characterization techniques such as scanning electron microscopy and contact angle were used for analyses of samples. Adult human dermal fibroblasts (neonatal) were utilized to evaluate the biocompatibility of the association of the electrospinning process of the biocompatible polymer (PCL) with TiO2 nanotubes on the Ti-30Ta alloy surface. The results of this study showed a favorable response for adhesion on the surface. This promising material is due to the modulation of the biological response.

Preparation, structural, microstructural, mechanical and cytotoxic characterization of as-cast Ti-25Ta-Zr alloys.

Titanium alloys have been widely used as biomaterials, especially for orthopedic prostheses and dental implants, but these materials have Young's modulus almost three times greater than human cortical bones. Because of this, new alloys are being produced for the propose of decreasing Young's modulus to achieve a more balanced mechanical compatibility with the bone. In this paper, it is reported the development of Ti-25Ta alloys as a base material, in which was introduced zirconium, with concentration varying between 0 and 40 wt%, with the aim of biomedical applications. The alloys were prepared in an arc-melting furnace. The microstructural analysis was performed by x-ray diffraction as well as optical and scanning electron microscopy. Selected mechanical properties were analyzed by microhardness and Young's modulus measurements, and cytotoxicity analysis by indirect test. X-ray measurements revealed the presence of α″ phase in the alloy without zirconium; α″ + ß phases for alloys with 10, 20, and 30 wt% of zirconium, and ß phase only for the alloy with 40 wt% of zirconium. These results were corroborated by the microscopy results. The hardness of the alloy was higher than that of cp-Ti due to the actions of zirconium and tantalum as hardening agents. The Young's modulus decreases with high levels of zirconium due to the stabilization of the ß phase. The cytotoxicity test showed that the extracts of studied alloys are not cytotoxic for osteoblast cells in short periods of culture.

Effect of porous tantalum on the biological response of human peripheral mononuclear cells exposed to Porphyromonas gingivalis.

AIM: To evaluate biological behavior of human peripheral mononuclear cells (PBMC) in contact with porous tantalum (PT) and Porphyromonas gingivalis (Pg). METHODS: Pg was incubated for 8 hours. The groups formed were: PBMC (control), PBMC + PT, PBMC + Pg and PBMC + PT + Pg. Cell viability was evaluated using MTT assay. The morphology and adhesion of PBMC to PT was evaluated using scanning electron microscopy. Expression of interleukin (IL)-10, transforming growth factor (TGF)-ß, matrix metallopeptidase (MMP)-9 and receptor activator of nuclear factor-κΒ ligand (RANKL) was determined by enzyme-linked immunosorbent assay. RESULTS: MTT assay revealed that PT did not interfere in the mitochondrial activity of PBMC (P > .05). Scanning electron microscopy showed the adherence of PBMC to PT. IL-10 levels in PBMC + PT were similar to PBMC and lower than PBMC + Pg. TGF-ß levels in PBMC + PT were higher than PBMC and PBMC + Pg. MMP-9 levels in PBMC + PT were similar to PBMC and lower than PBMC + Pg and PBMC + PT + Pg. RANKL levels in PBMC + PT were lower than in PBMC. CONCLUSION: PT did not affect PBMC viability, allowed cell adhesion, reduced expression of RANKL and enhanced TGF-ß in comparison with the control group.

Recovery of the Hip Rotation Center with Tantalum in Revision Arthroplasty / Recuperação do centro de rotação do quadril com tântalo em artroplastias de revisão

Abstract Objective The objective of the present study is to evaluate the restoration capacity of the hip anatomic rotation center with the use of acetabular tantalum cups, associated or not with addition wedges. Methods Retrospective analysis of patients undergoing hip arthroplasty revision using tantalum between June 2013 and April 2017. The abduction angle of the acetabular component and the horizontal and vertical distances of the component to the center of anatomical rotation of the hipwere evaluated. The measurements were made through baseline radiographs performed in the preoperative period and at the last follow-up visit. Results A sample of 21 patients was obtained, 11 (52%) men and 10 (48%) women, with amean age of 62 ± 13 years old. The mean abduction angle of the acetabular cup decreased from 48.76° ± 13.88 ° in the preoperative period to 38.52° ± 10.08 ° in the postoperative period, and this difference was statistically significant (p = 0.001). The distances from the center of rotation of the prosthesis relative to the center of anatomical rotation of the hip were also lower after revision surgery with tantalum. The mean horizontal distance of 12.74 ± 10.59 mm was reduced to 7.11 ± 4.84 mm, and the mean vertical distance was reduced from 14.79 ± 10.05 mm to 4.89 ± 6.21 mm, and these reductions were statistically significant (p < 0.001). Conclusion Hip arthroplasty revision with tantalum cups, associated or not with addition wedges, significantly recovered the anatomical rotation center of the hip.

Resumo Objetivo O objetivo do presente estudo é avaliar a capacidade de restauração do centro de rotação anatômico do quadril com uso de copas acetabulares de tântalo associado ou não a cunhas de adição. Métodos Análise retrospectiva dos pacientes submetidos a revisão de artroplastia do quadril comuso de tântalo entre o período de junho de 2013 e abril de 2017. Foramavaliados o ângulo de abdução do componente acetabular e as distâncias horizontal e vertical do componenteao centro de rotação anatômicodoquadril.Asmedidas foramrealizadas através de radiografias da bacia realizadas no pré-operatório e na última visita de seguimento. Resultados Obteve-se uma amostra de 21 pacientes, 11 (52%) homens e 10 (48%) mulheres, com média de idade de 62 ± 13 anos. O ângulo médio de abdução da copa acetabular reduziu de 48,76° ± 13,88° no pré-operatório para 38,52° ± 10,08° no pósoperatório, sendo esta diferença estatisticamente significativa (p = 0,001). As distâncias do centro de rotação da prótese em relação ao centro de rotação anatômico do quadril também foram menores após a cirurgia de revisão com o tântalo. A distância média horizontal de 12,74 ± 10,59 mm foi reduzida para 7,11 ± 4,84 mm, e a distância média vertical foi reduzida de 14,79 ± 10,05 mm para 4,89 ± 6,21 mm, sendo essas reduções estatisticamente significativas (p < 0,001). Conclusão As revisões de artroplastia do quadril comcopas de tântalo, associadas ou não a cunhas de adição, recuperaram de forma significativa o centro de rotação anatômico do quadril.

Tailoring the synthesis of tantalum-based thin films for biomedical application: Characterization and biological response.

The aim of this study was to tailor the deposition parameters of magnetron sputtering to synthetize tantalum oxide (TaxOy) films onto commercially pure titanium (cpTi) surface. The structural and optical properties, morphology, roughness, elemental chemical composition and surface energy were assessed. The impact of TaxOy films on initial Streptococcus sanguinis adhesion was investigated. The morphology and spreading of pre-osteoblastic (MC3T3-E1) cells on a crystalline tantalum oxide film were evaluated. TaxOy films with estimated thickness of 600 nm and different structures (amorphous or crystalline) were produced depending on the various oxygen flow rates and parameters used. X-ray diffraction analysis revealed that the 8 O2 sccm (600 °C/400 W) group showed crystallization corresponding to the ß-Ta2O5 phase. Optical analysis showed that the 4 O2 sccm (200 °C 300 W) to 8 O2 sccm (600 °C 300 W) groups and 10 O2 sccm (200 °C 300 W) group presented regular and large-amplitude interference oscillations, suggesting high optical homogeneity of the films. The crystalline ß-Ta2O5 coating showed higher roughness and surface energy values than the other groups (P < .05) and was biocompatible. Compared with cpTi, the amorphous and crystalline tantalum oxide films did not increase bacterial adhesion (P > .05). By tailoring the deposition parameters, we synthetized a crystalline ß-Ta2O5 coating that improved titanium surface properties and positively affected cell spreading and morphology, making it a promising surface treatment for titanium-based implants.

Uso de copas de tantalio trabecular para la reconstrucción acetabular compleja: Resultados de una serie de 42 casos y un seguimiento promedio de tres años / Trabecular metal cup outcomes in complex acetabular reconstruction. Review of 42 cases with a 3-year follow-up

Introducción: El objetivo de este estudio es analizar nuestros resultados clinico-radiologicos con el uso de copas de tantalio trabecular para la reconstruccion de acetabulos complejos, tanto en cirugias primarias como en revisiones, y compararlos con series similares de otros autores. Materiales y Métodos: Se llevo a cabo una revision retrospectiva de una serie de 42 cirugias (29 revisiones y 13 artroplastias primarias) en 40 pacientes, entre marzo de 2010 y marzo de 2016. La serie incluyo a 20 mujeres y 20 hombres, con una edad promedio de 60 anos (rango 27-93). El seguimiento promedio fue de 37 meses (rango 12-84). Todos los pacientes fueron tratados con el mismo tipo de metal trabecular. Resultados: Al promedio de seguimiento mencionado la supervivencia del componente acetabular fue del 97,6%. Un paciente fue tratado con artroplastia de reseccion debido a una infeccion persistente. La tasa de complicaciones totales fue del 12% y el promedio del Harris Hip Score posoperatorio fue de 81,54 (rango 63,25-92,75). Conclusiones: Aunque se necesita un seguimiento mas prolongado, el uso de copas de metal trabecular logra resultados prometedores para el tratamiento de acetabulos complejos. Nivel de Evidencia: IV

Introduction: The purpose of this paper is to review of our clinical and radiological results with the use of trabecular metal cups for complex acetabular reconstruction, both in primary and revision total hip arthroplasties, and to compare our results with those in similar series from other authors. Methods: A series of 42 surgeries (29 hip revisions and 13 primary total hip arthroplasties) in 40 patients, between March 2010 and March 2016 was retrospectively reviewed. The series included 20 women and 20 men, with a mean age of 60 years (range 27-93). The mean follow-up was 37 months (range 12-84). All patients were treated with the same type of trabecular metal. Results: At the average follow-up, the survival of the acetabular component was 97.6%. One patient required resection arthroplasty due to persistent infection. Overall complication rate was 12% and the average postoperative Harris Hip Score was 81.54 (range 63.25-92.75). Conclusions: Despite further follow-up is needed, trabecular metal cup use for complex acetabular reconstruction shows promising results. Level of Evidence: IV

Safety of Onyx Transarterial Embolization of Skull Base Dural Arteriovenous Fistulas from Meningeal Branches of the External Carotids also Fed by Meningeal Branches of Internal Carotid or Vertebral Arteries.

PURPOSE: To analyze the angiographic and clinical results of transarterial embolization with Onyx (Medtronic-Covidien, Irvine, CA) in dural arteriovenous fistulas (DAVFs) partially fed by arteries arising from the carotid siphon or the vertebral arteries. METHODS: We isolated 40 DAVFs supplied by either the tentorial artery of the internal carotid artery (ICA) or the posterior meningeal artery of the vertebral artery. These DAVFs were embolized with Onyx through the middle meningeal artery or the occipital artery. We reviewed the occurrence of reflux into the arteries of carotid or vertebral origin. RESULTS: In all the cases, reflux occurred into the first millimeters of the DAVF arterial feeders arising from carotid or vertebral arteries but slowly enough to be controlled by interruption of Onyx injection. Reflux was always minimal and Onyx never reached the ostium of the arteries. No cerebral ischemic complications occurred in our series. CONCLUSION: The behavior of Onyx is clearly different from that of cyanoacrylate glue, resulting in superior control during injection. Reflux into arteries arising from the ICA or vertebral artery during DAVF treatment always carries a risk of unintentional non-target embolization of normal cerebral vasculature but Onyx appears to be safe in this situation.

Unruptured Brain Arteriovenous Malformations: Primary ONYX Embolization in ARUBA (A Randomized Trial of Unruptured Brain Arteriovenous Malformations)-Eligible Patients.

BACKGROUND AND PURPOSE: In light of evidence from ARUBA (A Randomized Trial of Unruptured Brain Arteriovenous Malformations), neurovascular specialists had to reconsider deliberate treatment of unruptured brain arteriovenous malformations (uBAVMs). Our objective was to determine the outcomes of uBAVM treated with primary embolization using ethylene vinyl alcohol (ONYX). METHODS: Patients with uBAVM who met the inclusion criteria of ARUBA and were treated with primary Onyx embolization were assigned to this retrospective study. The primary outcome was the modified Rankin Scale score. Secondary outcomes were stroke or death because of uBAVM or intervention and uBAVM obliteration. RESULTS: Sixty-one patients (mean age, 38 years) were included. The median observation period was 60 months. Patients were treated by embolization alone (41.0%), embolization and radiosurgery (57.4%), or embolization and excision (1.6%). Occlusion was achieved in 44 of 57 patients with completed treatment (77.2%). Forty-seven patients (77.1%) had no clinical impairment at the end of observation (modified Rankin Scale score of <2). Twelve patients (19.7%) reached the outcome of stroke or death because of uBAVM or intervention. Treatment-related mortality was 6.6% (4 patients). CONCLUSIONS: In uBAVM, Onyx embolization alone or combined with stereotactic radiosurgery achieves a high occlusion rate. Morbidity remains a challenge, even if it seems lower than in the ARUBA trial.

Antimicrobial and anti-biofilm properties of polypropylene meshes coated with metal-containing DLC thin films.

A promising strategy to reduce nosocomial infections related to prosthetic meshes is the prevention of microbial colonization. To this aim, prosthetic meshes coated with antimicrobial thin films are proposed. Commercial polypropylene meshes were coated with metal-containing diamond-like carbon (Me-DLC) thin films by the magnetron sputtering technique. Several dissimilar metals (silver, cobalt, indium, tungsten, tin, aluminum, chromium, zinc, manganese, tantalum, and titanium) were tested and compositional analyses of each Me-DLC were performed by Rutherford backscattering spectrometry. Antimicrobial activities of the films against five microbial species (Candida albicans, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Enterococcus faecalis) were also investigated by a modified Kirby-Bauer test. Results showed that films containing silver and cobalt have inhibited the growth of all microbial species. Tungsten-DLC, tin-DLC, aluminum-DLC, zinc-DLC, manganese-DLC, and tantalum-DLC inhibited the growth of some strains, while chromium- and titanium-DLC weakly inhibited the growth of only one tested strain. In-DLC film showed no antimicrobial activity. The effects of tungsten-DLC and cobalt-DLC on Pseudomonas aeruginosa biofilm formation were also assessed. Tungsten-DLC was able to significantly reduce biofilm formation. Overall, the experimental results in the present study have shown new approaches to coating polymeric biomaterials aiming antimicrobial effect.

Biocompatibility and mineralized nodule formation of Neo MTA Plus and an experimental tricalcium silicate cement containing tantalum oxide.

AIM: To evaluate the biocompatibility and mineralized nodule formation of an experimental tricalcium silicate cement with tantalum oxide (TSC/Ta2 O5 ) as radiopacifier, Neo MTA Plus (Avalon Biomed Inc., Bradenton, FL, USA) and MTA (Angelus, Londrina, PR, Brazil) on human osteoblast-like cells (Saos-2). METHODOLOGY: Biocompatibility was evaluated by 3-(4,5-dimethyl-thiazoyl)-2,5-diphenyl-tetrazolium bromide (MTT) and neutral red (NR) assays, after exposure of Saos-2 to cement extracts at 1 : 1, 1 : 2, 1 : 4 and 1 : 8 dilutions for 24 h. Bioactivity was evaluated by alkaline phosphatase (ALP) activity, and calcium deposits were detected with alizarin red staining (ARS). Statistical analysis was performed with analysis of variance and Bonferroni or Tukey post-test (α = 0.05). RESULTS: The MTT assay revealed lower cytotoxicity for NEO and MTA (P < 0.05), and higher for TSC/Ta2 O5 at 1 : 1 and 1 : 2 dilutions when compared to serum-free medium - control (P > 0.05). At 1 : 4 dilution, the TSC/Ta2 O5 cytotoxicity was similar to the control (P > 0.05). At 1 : 8 dilution, cell viability was significantly greater than the control (P < 0.05). Saos-2 cell viability performed using the NR assay at all dilutions revealed no cytotoxic effect of MTA, NEO and TSC/Ta2 O5 . ALP activity at 1 and 3 days was similar to the control (P > 0.05). TSC/Ta2 O5 had significantly greater ALP activity at 7 days when compared with the control (P < 0.05). All materials induced the production of mineralized nodules, and NEO produced significantly more mineralized nodules than MTA and TSC/Ta2 O5 (P < 0.05). CONCLUSIONS: Neo MTA Plus and TSC/Ta2 O5 were biocompatible and induced ALP activity in Saos-2 cells. Both materials induced mineralized nodule formation by Saos-2 with Neo MTA Plus producing significantly more.

Acetabular revision in total hip arthroplasty with tantalum augmentation and lyophilized bovine xenograft / Revisão acetabular em artroplastia total de quadril com cunhas de tântalo associadas a enxerto ósseo bovino liofilizado

Abstract Objective To evaluate a mixed technique of acetabular reconstruction, which uses trabecular metal in the form of tantalum augments associated with lyophilized bovine xenograft. Methods Fifteen patients were evaluated prospectively, who underwent acetabular reconstruction with impacted lyophilized bovine xenograft associated with the use of tantalum augments. The main outcome was the failure of the tantalum-bone interface. Results The population had a mean age of 58.33 years ± 14.27; the majority was female, 80%. Of the total subjects, 66.7% were operated for failure in primary arthroplasty. The mean follow-up time was 45.2 months ± 11.39. The failure rate of the method in the period and population studied was 6.7%. Conclusion An extremely high index (93.3%) of success was observed in an average time of 45.2 months of follow-up. Data were comparable to current literature, demonstrating that the technique employed and proposed is adequate for hip reconstruction in young patients.

Resumo Objetivo Avaliar uma técnica mista de reconstrução acetabular que usa metal trabecular na forma de cunhas de tântalo associadas com enxerto ósseo bovino liofilizado. Métodos Foram avaliados prospectivamente 15 pacientes submetidos à reconstrução acetabular com enxerto bovino liofilizado impactado associado ao uso de cunhas de tântalo. O principal desfecho avaliado foi a falha da interface tântalo-osso. Resultados A população apresentou idade média de 58,33 anos ± 14,27, a maioria do sexo feminino 80%. Do total, 66,7% foram operados por falha da artroplastia primária. O tempo médio de seguimento foi de 45,2 meses ± 11,39 meses. A taxa de falha do método no período e na população estudada foi de 6,7%. Conclusão Observou-se um índice extremamente elevado (93,3%) de sucesso em um tempo médio de 45,2 meses de seguimento. Os dados são comparáveis à literatura corrente, o que demonstra que a técnica empregada e proposta é adequada para reconstrução de quadril em pacientes jovens.

A search for the ground state structure and the phase stability of tantalum pentoxide.

Tantalum pentoxide (Ta2O5) is a wide-gap semiconductor that presents good catalytic and dielectric properties, conferring to this compound promising prospective use in a variety of technological applications. However, there is a lack of understanding regarding the relations among its crystalline phases, as some of them are not even completely characterized and there is currently no agreement about which models better explain the crystallographic data. Additionally, its phase diagram is unknown. In this work we performed first-principles density functional theory calculations to study the structural properties of the different phases and models of Ta2O5, the equation of state and the zone-centered vibrational frequencies. From our results, we conclude that the phases that are built up from only distorted octahedra instead of combinations with pentagonal and/or hexagonal bipyramids are energetically more favorable and dynamically stable. More importantly, this study establishes that, given the pressure range considered, the B-phase is the most favorable structure and there is no a crystallographic phase transition to another phase at high-pressure. Additionally, for the equilibrium volume of the B-phase and the λ-model, the description of the electronic structure and optical properties were performed using semi-local and hybrid functionals.

Porous tantalum rods for treating osteonecrosis of the femoral head.

This study evaluated the outcomes of using porous tantalum rods for the treatment of osteonecrosis of the femoral head (ONFH). We performed core decompression and inserted porous tantalum implants in 149 patients (168 consecutive hips) with ONFH. Hips had large (65), medium (64), or small (39) lesions; 63 lesions were lateral, 68 were central, and 35 were medial. Conversion to total hip arthroplasty (THA) was the end point of this survey. A total of 130 cases (138 hips) were followed. The mean follow-up time was 38.46 ± 5.76 months; 43 hips (31%) were converted to or needed THA. Of the 43 hips requiring THA, 33 had large lesions, including 1 medial, 3 central, and 29 lateral lesions; 9 had medium, lateral lesions, and 1 hip had a small, lateral lesion. Bone grafting was used in 59 hips, with 3 hips failing; 40 of 79 hips without bone grafts failed. The sum distances between the tops of the rods and the lateral lesion boundaries (SDTL, mm) were measured in anteroposterior and lateral radiographs. In the failure and spared groups, the average SDTLs were 7.65 ± 2.759 and 0.83 ± 2.286 mm, respectively. The survival of porous tantalum rods used for treating early-stage ONFH was affected by the size and location of the lesion, whether or not a bone graft was used, as well as the distance between top of the rod and the lateral boundary of the lesion.

Experimental titanium alloys for dental applications.

STATEMENT OF PROBLEM: Although the use of titanium has increased, casting difficulties limit routine use. PURPOSE: The purpose of the present study was to compare the mechanical properties and biocompatibility of the experimental titanium alloys titanium-5-zirconium, titanium-5-tantalum, and titanium-5-tantalum-5-zirconium (in wt%) with those of commercially pure titanium. MATERIAL AND METHODS: Specimens of titanium alloys and commercially pure titanium were cast by using plasma. Their modulus of elasticity and ultimate tensile strength were determined in a universal testing machine. Biocompatibility was evaluated with SCC9 cells. In periods of 1, 4, 7, 10, and 14 days, cell proliferation was evaluated by the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) tetrazolium reduction assay, and cell viability was evaluated in the 7-day period. Cell morphology was evaluated at 2, 12, and 24 hours. Modulus of elasticity, ultimate tensile strength, and cell viability were analyzed by 1-way ANOVA and the Bonferroni test; cell proliferation data were compared by 2-way ANOVA (alloy versus time) and by the Bonferroni test; and the cell morphology data were analyzed by split-plot design. All statistical tests were performed at the 95% confidence level (P<.05). RESULTS: Titanium-5-tantalum presented the lowest modulus of elasticity and ultimate tensile strength, whereas titanium-5-zirconium and titanium-5-tantalum-5-zirconium were statistically similar to commercially pure titanium. Cell proliferation and viability were not affected by any alloy being similar to those observed for commercially pure titanium. No noticeably differences were found in the morphology of cells cultured on any alloy and commercially pure titanium. CONCLUSION: Experimental alloys, especially titanium-5-zirconium and titanium-5-tantalum-5-zirconium, presented promising mechanical results for future studies and clinical applications. In addition, these alloys, evaluated by cell proliferation, viability, and morphology, were found to be biocompatible in vitro.

Interaction between mesenchymal stem cells and Ti-30Ta alloy after surface treatment.

In this study, in vitro cytocompatibility was investigated in the Ti-30Ta alloy after two kinds of surfaces treatments: alkaline and biomimetic treatment. Each condition was evaluated by scanning electron microscopy/energy-dispersive X-ray spectroscopy. Cellular adhesion, viability, protein expression, morphology, and differentiation were evaluated with Bone marrow stromal cells (MSCs) to investigate the short and long-term cellular response by fluorescence microscope imaging and colorimetric assays techniques. Two treatments exhibited similar results with respect to total protein content and enzyme activity as compared with alloy without treatment. However, it was observed improved of the biomineralization, bone matrix formation, enzyme activity, and MSCs functionality after biomimetic treatment. These results indicate that the biomimetic surface treatment has a high potential for enhanced osseointegration.

Wear resistance of experimental titanium alloys for dental applications.

The present study evaluated microstructure, microhardness and wear resistance of experimental titanium alloys containing zirconium and tantalum. Alloys were melted in arc melting furnace according to the following compositions: Ti-5Zr, Ti-5Ta and Ti-5Ta-5Zr (%wt). Hemispheres and disks were obtained from wax patterns that were invested and cast by plasma. Microstructures were evaluated using optical microscopy and X-ray diffraction (XRD) analysis and also Vickers microhardness was measured. Hemispherical samples and disks were used for 2-body wear tests, performed by repeated grinding of the samples. Wear resistance was assessed as height loss after 40,000 cycles. The data were compared using ANOVA and post-hoc Tukey test. Ti-5Zr presented a Widmanstätten structure and the identified phases were α and α' while Ti-5Ta and Ti-5Ta-5Zr presented α, ß, α' and α" phases, but the former presented a lamellar structure, and the other, acicular. The microhardness of Ti-5Zr was significantly greater than other materials and cp Ti presented wear resistance significantly lower than experimental alloys. It was concluded that wear resistance was improved when adding Ta and Zr to titanium and Zr increased microhardness of Ti-5Zr alloy.

Cirugía de revisión acetabular utilizando un cotilo modular con superficie de metal trabecular de tantalio: resultados a corto plazo / Acetabular revision surgery using a modular acetabular cup coated with trabecular metal of tantalum: short term results

Objectives: To evaluate short-term clinical results of patients performed acetabular revision surgery using a Trabecular Tantalum coated modular acetabular cups. Materials and Methods: This is a retrospective and descriptive analysis of a serie of 32 consecutive patients (34 hips) with acetabular revision surgery (23 women, 9 men, mean age 70.7 years), mean follow-up 32 month (12-60). The Paprosky and the AAOS acetabular defects classifications were assessed. According to Paprosky acetabular defects classification, there were eleven type I, two IIA, three IIB, nine IIC, seven IIIA and two IIIB. According to AAOS acetabular defects classification there were thirteen patients with type 1, nine patients with type 2, ten type 3 and two type 4. The percentage of own acetabular bone in contact with the new cup was recorded for each patient at the time of surgery and was 45 percent (range from 20 to 80 percent), with 23 patients presenting less than 50 percent of bone contact (mean 35 percent). Postoperatively, osseous integration was radiographically assessed. Functional results were evaluated according to the Harris Hip Score (HSS). The complications related to the implant were also recorded. Results: In all radiographic assessments performed at 3, 6 and 12 month postoperatively an integrated cup without signs of migration or osteolysis was observed. Four patients (11.8 percent) presented recurrent hip dislocation that required a revision surgery without further cup revision. The final clinical assessment was performed at a mean of 26 month after surgery (12-60) with a mean HHS of 91.8 points. Conclusion: Trabecular tantalum coated modular acetabular cups in acetabular revision surgery shows good short term clinical results even with acetabular defects greater than 50 percent. No cup loosening was observed in these series.

Objetivo: Evaluar los resultados clínicos a corto plazo de pacientes sometidos a cirugía de revisión acetabular utilizando cotilos modulares con superficie de metal trabecular de tantalio. Material y Métodos: Estudio retrospectivo-descriptivo de una serie consecutiva de 32 pacientes (34 caderas) sometidos a cirugía de revisión acetabular (23 mujeres, 9 hombres, edad promedio 70,7 años), seguimiento promedio 32 meses (12-60). Se clasifican los defectos acetabulares de acuerdo ala clasificación de Paprosky y de la AAOS. Según la clasificación de Paprosky de los defectos acetabulares, 11 pacientes tenían categoría I, 2 categoría IIA, 3 categoría IIB, 9 categoría IIC, 7 categoría IIIA y 2 categoría IIIB. Según la clasificación de la AAOS, 13 pacientes correspondieron a nivel 1, 9 pacientes a nivel 2, 10 a nivel 3 y 2 a nivel 4. Se registra el porcentaje de hueso propio acetabular en contacto con el nuevo cotilo de cada paciente que fue en promedio 45 por ciento (20-80 por ciento), presentándose en 23 caderas un porcentaje < 50 por ciento, el cual fue en promedio 35 por ciento. En el postoperatorio se evalúa la integración ósea mediante radiografías de pelvis. Se evalúan los resultados funcionales mediante el HHS (Harris Hip Score) y las complicaciones postoperatorias relacionadas con el implante. Resultados: En todas las radiografías postoperatorias realizadas a los 3, 6 y 12 meses se evidenciaba el cotilo integrado, sin signos de migración ni osteolisis. Cuatro pacientes (11,8 por ciento) presentaron luxaciones recidivantes de cadera, las cuales requirieron de una cirugía de revisión sin recambio del cotilo. La última evaluación clínica fue en promedio 26 meses tras la cirugía (12-60 meses) constatándose un HHS promedio de 91,8 puntos. Conclusión: El uso de cotilos modulares con revestimiento de metal trabecular de tantalio en cirugías de revisión acetabular presenta buenos resultados clínicos a corto plazo incluso en defectos óseos acetabulares superiores...