Cimentos ósseos injetáveis à base de ?-TCP

Mestrado em Materiais e Dispositivos BiomédicosEste trabalho teve como objectivo principal o desenvolvimento de cimentos de fosfatos de cálcio apatíticos injectáveis e com propriedades mecânicas adequadas para aplicações ortopédicas. Um objectivo secundário consistiu na incorporação de iões dopantes na rede cristalina do fosfato tricálcio (β-TCP) em substituição parcial do cálcio e no estudo dos seus efeitos nas transformações alotrópicas das fases TCP durante os ciclos térmicos com vista à obtenção da fase TCP. Os pós iniciais de fosfato tricálcio (não dopados, e dopados com Sr, Zn e Mn) utilizados neste estudo foram produzidos pelo processo de precipitação química por via húmida, seguindo-se o tratamento térmico com vista a obter as fases pretendidas (β-TCP e/ou α-TCP). A substituição parcial do Ca pelos iões dopantes mostrou ter fortes implicações em termos de estabilidade térmica da fase β-TCP, dificultando a transformação desta para α-TCP. Os resultados demonstraram que as transformações alotrópicas das fases TCP são também muito influenciadas por outros fatores experimentais tais como a taxa de arrefecimento e a presença de fases secundárias de pirofosfato de cálcio ou de hidroxiapatite. Os cimentos ósseos de fosfato de cálcio (CPC) foram preparados misturando os pós de α-TCP puros com soluções aquosas reativas de diferentes concentrações de hidrogenofosfato de sódio, como agente acelerador do tempo de presa. A algumas soluções aquosas adicionaram-se ainda aditivos (Aristoflex ®TAC, polietileno glicol 600) com a intensão deliberada de melhorar o comportamento das pastas cimentícias durante a extrusão. Contudo, aquando dos testes de injetabilidade, verificou-se que estes aditivos baixavam a percentagem de pasta extrudida. Verificou-se também que a distribuição do tamanho de partículas é um fator crucial no comportamento reológico das pastas cimentícias. A combinação do pó de α-TCP com 2,5 wt% de hidrogeno fosfato de sódio como líquido de presa, resultou em cimentos de apatite com propriedades interessantes do ponto de vista da injetabilidade, microestrutura, porosidade, resistência mecânica e fases cristalinas formadas. Com o intuito de uma eventual translação deste produto para o mercado procedeu-se a uma avaliação clínica por equivalência a produtos idênticos já disponíveis comercialmente, a qual deu origem a um relatório de investigação clínica.The main objective of this work was the development of injectable apatitic calcium phosphates cements with mechanical properties suitable for orthopaedic applications. A secondary objective was to incorporate doping ions into the crystalline lattice of tricalcium phosphate (β-TCP) in partial replacement of calcium and to study its effects on allotropic transformations of TCP phases during thermal cycles in order to obtain the TCP phase. The initial tricalcium phosphate powders (non-doped and doped with Sr, Zn and Mn) used in this study were produced by the wet chemical precipitation process, followed by heat treatment in order to obtain the desired phases (β-TCP and/or α-TCP). The partial substitution of Ca by the doping ions showed to have strong implications in terms of thermal stability of the β-TCP phase, making it difficult to transform to α-TCP. The results demonstrated that the allotropic TCP phase transformations are also noticeably affected by other experimental factors such as the cooling rate and the presence of secondary phases of calcium pyrophosphate or hydroxyapatite. The calcium phosphate (CPC) bone cement pastes were prepared by mixing the pure α-TCP powders with reactive aqueous solutions of different concentrations of sodium hydrogen phosphate as a settling accelerator. To some aqueous solutions, additives (Aristoflex®TAC, polyethylene glycol 600) were further added with the deliberate intention of improving the rheological behaviour of the cementitious pastes during extrusion. However, during the injectability tests, these additives were found to lower the percentage of extruded paste. It has also been found that the particle size distribution is a crucial factor in determining the rheological behaviour of cementitious pastes. The combination of α-TCP powder with 2.5 wt% sodium hydrogen phosphate as setting liquid resulted in apatite cements with interesting properties from the point of view of the injectability, microstructure, porosity, mechanical strength and crystalline phases formed. In order to pave the way of an eventual translation of this product into the market, a clinical evaluation was carried out by equivalence to identical products already commercially available, which gave rise to a clinical investigation report

A pain neuroscience education program for fibromyalgia patients with cognitive deficits: a case series

Trabalho apresentado na IFOMPT Conference, 4 a 8 de julho de 2016, Glasgow, Escóci

OPTIMIZATION OF ZIRCONIA INKS TO FABRICATE 3D POROUS SCAFFOLDS BY ROBOCASTING

High-performance bioceramics such as zirconia, alumina, and their composites, are attractive materials for the fabrication of load-bearing bone implants because of their outstanding mechanical properties, biocompatibility, corrosion resistance, and aesthetic quality. A suitable level of porosity and pore sizes with a few hundred microns are required for a good bone integration of the scaffolds. This requirement can be achieved through additive manufacturing, like robocasting. For this purpose, the optimization of colloidal inks is one of paramount importance as the rheological properties of the inks determine the quality of the three-dimensional structures. This target has not been satisfactorily accomplished in previous research works. The present study aims at closing this gap by carrying out a systematic investigation about the influence of the most important parameters that determine the printing ability of zirconia inks. The dispersing ability of the zirconia powder was studied in order to maximize the solids loading while keeping a high degree of homogeneity of the starting suspensions. The viscoelastic properties of the suspensions were then altered by adding suitable doses of a coagulating agent to obtain easily extrudable pastes for the robocasting process. The green samples were dried and sintered at the heating rate of 1ºC/min up to 600ºC, an holding at this temperature for 1 h, followed by an heating rate of 5ºC/min up to 1350ºC and holding for 1 h at this temperature, and then cooling down to room temperature. Zirconia inks with high fraction of solids (48 vol.%) could be successfully prepared. The extruded cylinders exhibited an excellent shape retention in scaffolds with different macropore sizes (200, 300, 400 and 500 mm)

Interpretação da experiência de dor, papel dos profissionais de saúde e efetividade da educação baseada na neurofisiologia da dor num caso de dor lombar crónica não específica.

Preprint de poster apresentado no XVII Congresso Português de Reumatologia, 7-10 de maio de 2014, Albufeira, Portuga

Resultados da Intervenção da Fisioterapia após Ligamentoplastia do LCA: Estudo Série de Casos

Introdução: A literatura sugere que o sucesso da ligamentoplastia do LCA está directamente relacionado com a reabilitação após cirurgia, permitindo ao utente o retorno a um estilo de vida activo. Objectivo: Descrever os resultados da intervenção da fisioterapia, às 6, 12 e 24 semanas, em indivíduos após ligamentoplastia do LCA. Metodologia: Realizou-se um estudo série de casos, com uma amostra não probabilística, constituída por 14 utentes (34 ± 11,92 anos) que cumpriam os critérios de inclusão e exclusão estabelecidos. Os utentes foram avaliados na 1ª sessão de fisioterapia e às 6, 12 e 24 semanas após cirurgia. Os resultados obtidos foram descritos ao nível da incapacidade funcional, da intensidade da dor e da percepção global de melhoria. Resultados: Observou-se uma tendência de melhoria ao longo das 24 semanas em todas as dimensões da KOOS-PT e na END, assim como na percepção de melhoria pelo utente, medida através da PGIC-PT. Às 6 semanas, as melhorias nas variáveis de resultados foram superiores às encontradas às 12 e 24 semanas, ao nível da intensidade da dor e incapacidade funcional (à excepção das dimensões KOOS- actividades desportivas e de lazer e a KOOSqualidade de vida). Conclusão: Os resultados sugerem que apesar da heterogeneidade da prática clínica, a intervenção da fisioterapia parece ter contribuído para melhorias ao nível da capacidade funcional e da dor, em indivíduos submetidos a ligamentoplastia do LCA e que essas melhorias são percepcionadas pelos participantes como clinicamente importantes.Abstract:Introduction: The success of ACL reconstruction is directly related with the rehabilitation after the surgery, allowing the patient to an active lifestyle return. Objective: To describe the results of physical therapy intervention, at 6, 12 and 24 weeks, in subjects after ACL reconstruction. Methodology: A case series design with a sample of 14 patients (34 ± 11,92 years) that fulfilled the pre- established inclusion and exclusion criteria. Patients were evaluated in four moments: in the first session of physiotherapy and at 6, 12 and 24 weeks after surgery. The results obtained after physiotherapy intervention were described at the level of functional disability, pain and global perception of change. Results: It was found that there was a trend of improvement, clinically important, over the 24 weeks in all dimensions of KOOS and in the NPRS. At 6 weeks, improvements were superior to those found at 12 and 24 weeks, at the level of functional disability (with the exception of the KOOS-sports and recreation function and KOOS-knee related quality of life dimensions) and pain. Conclusion:The results of this study suggest that in spite of the heterogeneity of clinical practice, physical therapy intervention provides improvements in terms of functional disability and pain in subjects after ACL reconstruction

Cuttlefish Bone-Derived Biphasic Calcium Phosphate Scaffolds Coated with Sol-Gel Derived Bioactive Glass

The combination of calcium phosphates with bioactive glasses (BG) has received an increased interest in the field of bone tissue engineering. In the present work, biphasic calcium phosphates (BCP) obtained by hydrothermal transformation of cuttlefish bone (CB) were coated with a Sr-, Mg- and Zn-doped sol-gel derived BG. The scaffolds were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. The initial CB structure was maintained after hydrothermal transformation (HT) and the scaffold functionalization did not jeopardize the internal structure. The results of the in-vitro bioactivity after immersing the BG coated scaffolds in simulated body fluid (SBF) for 15 days showed the formation of apatite on the surface of the scaffolds. Overall, the functionalized CB derived BCP scaffolds revealed promising properties, but further assessment of the in-vitro biological properties is needed before being considered for their use in bone tissue engineering applications

Bioactive Glasses and Glass-Ceramics for Healthcare Applications in Bone Regeneration and Tissue Engineering

The discovery of bioactive glasses (BGs) in the late 1960s by Larry Hench et al. was driven by the need for implant materials with an ability to bond to living tissues, which were intended to replace inert metal and plastic implants that were not well tolerated by the body. Among a number of tested compositions, the one that later became designated by the well-known trademark of 45S5 Bioglass® excelled in its ability to bond to bone and soft tissues. Bonding to living tissues was mediated through the formation of an interfacial bone-like hydroxyapatite layer when the bioglass was put in contact with biological fluids in vivo. This feature represented a remarkable milestone, and has inspired many other investigations aiming at further exploring the in vitro and in vivo performances of this and other related BG compositions. This paradigmatic example of a target-oriented research is certainly one of the most valuable contributions that one can learn from Larry Hench. Such a goal-oriented approach needs to be continuously stimulated, aiming at finding out better performing materials to overcome the limitations of the existing ones, including the 45S5 Bioglass®. Its well-known that its main limitations include: (i) the high pH environment that is created by its high sodium content could turn it cytotoxic; (ii) and the poor sintering ability makes the fabrication of porous three-dimensional (3D) scaffolds difficult. All of these relevant features strongly depend on a number of interrelated factors that need to be well compromised. The selected chemical composition strongly determines the glass structure, the biocompatibility, the degradation rate, and the ease of processing (scaffolds fabrication and sintering). This manuscript presents a first general appraisal of the scientific output in the interrelated areas of bioactive glasses and glass-ceramics, scaffolds, implant coatings, and tissue engineering. Then, it gives an overview of the critical issues that need to be considered when developing bioactive glasses for healthcare applications. The aim is to provide knowledge-based tools towards guiding young researchers in the design of new bioactive glass compositions, taking into account the desired functional properties

results from a 10-year population-based cohort

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10-year follow-up of a population-based cohort

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a cross-sectional population-based study

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