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Comportamento mecânico de estruturas auxéticas com gradiente de funcionalidade para substituição de discos intervertebrais
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Avaliando em termos de custos à escala global, um dos maiores problemas de saúde é a degeneração dos discos intervertebrais.
Os discos intervertebrais (IVD) localizam-se entre as vértebras e são elementos que absorvem os choques, estes conferem rigidez e flexibilidade à coluna, na qual é necessário para o suporte de peso, movimentação do tronco e ajuste de posição, indispensável para equilíbrio e postura. É uma estrutura complexa, tanto mecânica como biologicamente, sendo formada por uma camada externa resistente de fibrocartilagem chamada Annulus Fibrosus (AF), a qual por sua vez encapsula um núcleo mole composto por um gel semifluido chamado Nucleus Pulposus (NP), as duas estruturas são limitadas superior e inferiormente pelas vértebras.
A degeneração do disco intervertebral é marcada pela desidratação do NP, reduzindo a pressão hidrostática no interior do núcleo, resultando numa perda de capacidade de suporte de forças compressivas, durante o período activo, e na recuperação da altura do núcleo nos períodos de descanso. Esta situação compromete o papel de amortecedor por parte do NP, que por sua vez transfere estas forças ao AF. Esta transferência resultará em fissuras no AF, deteriorando o disco intervertebral, permitindo a infiltração interna de vasos e nervos, potencialmente incapacitando o indivíduo, levando a um decréscimo da qualidade de vida do mesmo.
Este projeto assenta numa primeira abordagem ao desenvolvimento de materiais compósitos com propriedades auxéticas que possam mimetizar as propriedades mecânicas do disco intervertebral, através da fabricação de uma estrutura em TPU (Poliuretano Termoplástico) por impressão aditiva, com propriedades auxéticas, capaz de mimetizar o comportamento do AF, na produção de um hidrogel à base de quitosano, capaz de mimetizar o comportamento do NP, seguido da sua impregnação na estrutura de TPU e por fim o estudo da sua bioatividade.
From a global cost standpoint, one of the most significant health problems is the degeneration of the intervertebral discs. The intervertebral discs (IVD) are located between vertebrae, they are elements that absorb chocks and work to provide rigidity and flexibility to the spine, in which it is necessary for weight support, trunk movement and position adjustment essential for balance and posture. It is a complex structure, both mechanically and biologically, formed by a resistant outer layer of fibrocartilage, called Annulus Fibrosus (AF), which in turn encapsulates a soft core composed of a semi-fluid gel, called Nucleus Pulposus (NP); these two structures are limited both above and below by the vertebrae. Degeneration of the intervertebral disc is marked by dehydration of the NP, reducing the hydrostatic pressure inside the nucleus, resulting in a loss of capacity to support compressive forces, during the active period, and in the recovery of the nucleus height in the rest periods. This situation compromises the role of shock absorber by the NP, which in turn transfers theses forces to the AF. This transfer will result in cracks in the AF, deteriorating the intervertebral disc, allowing the internal infiltration of vessels and nerves, potentially incapacitating the individual, leading to a decrease in his quality of life. This project is based on a first approach to the development of composite materials with auxetic properties that can mimic the mechanical properties of the intervertebral disc, through the manufacture of a TPU structure by 3D printing, with auxetic properties, capable of mimicking the behavior of the AF, the production of a chitosan-based hydrogel, capable of mimicking the behavior of NP, followed by its impregnation in the TPU structure and finally the study of its bioactivity.
From a global cost standpoint, one of the most significant health problems is the degeneration of the intervertebral discs. The intervertebral discs (IVD) are located between vertebrae, they are elements that absorb chocks and work to provide rigidity and flexibility to the spine, in which it is necessary for weight support, trunk movement and position adjustment essential for balance and posture. It is a complex structure, both mechanically and biologically, formed by a resistant outer layer of fibrocartilage, called Annulus Fibrosus (AF), which in turn encapsulates a soft core composed of a semi-fluid gel, called Nucleus Pulposus (NP); these two structures are limited both above and below by the vertebrae. Degeneration of the intervertebral disc is marked by dehydration of the NP, reducing the hydrostatic pressure inside the nucleus, resulting in a loss of capacity to support compressive forces, during the active period, and in the recovery of the nucleus height in the rest periods. This situation compromises the role of shock absorber by the NP, which in turn transfers theses forces to the AF. This transfer will result in cracks in the AF, deteriorating the intervertebral disc, allowing the internal infiltration of vessels and nerves, potentially incapacitating the individual, leading to a decrease in his quality of life. This project is based on a first approach to the development of composite materials with auxetic properties that can mimic the mechanical properties of the intervertebral disc, through the manufacture of a TPU structure by 3D printing, with auxetic properties, capable of mimicking the behavior of the AF, the production of a chitosan-based hydrogel, capable of mimicking the behavior of NP, followed by its impregnation in the TPU structure and finally the study of its bioactivity.
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Tissue Engineering Compression Chitosan Nucleus Pulposus Annulus Fibrosus Auxetic