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Abstract(s)
O osso é um tecido vivo em constante renovação, capaz de adaptar a sua geometria e a
sua estrutura interna consoante as necessidades mecânicas e fisiológicas. A adaptação do osso
consiste na reabsorção de osso antigo e na formação de osso novo. Esta adaptação é designada
por remodelação óssea, tendo como objectivo prevenir a acumulação de danos microscópicos
minimizando a possibilidade de fractura do osso e manter a homeostasia mineral,.
O mecanismo da remodelação óssea envolve processos complexos que dependem de
vários factores como as interacções bioquímicas, as coordenações das actividades da unidade
básica multicelular (BMU) que são constituídas pelas células de osteoblastos e células de
osteoclastos, e as respostas aos estímulos mecânicos.
As abordagens exclusivamente experimentais, tanto in vivo como in vitro, não nos
permitem obter uma compreensão global de um fenómeno tão complexo como a remodelação
óssea. Para compreender melhor este mecanismo, é útil o desenvolvimento de novos modelos
matemáticos que integrem os conhecimentos teóricos e experimentais e que permitam a
compreensão das interacções mais relevantes, possibilitando a realização de simulações virtuais
para verificar novas hipóteses teóricas.
Pretende-se, com o presente trabalho, fazer uma revisão actualizada de alguns modelos
matemáticos e computacionais que foram elaborados para estudar a remodelação óssea. O
desenvolvimento dos modelos matemáticos incide sobretudo em 2 âmbitos: o nível mecânico e
o nível metabólico. Os modelos matemáticos desenvolvidos permitem descrever o
comportamento e o funcionamento da remodelação óssea. Em seguida, implementar um novo
modelo matemático que abranja simultaneamente os factores mecânicos e metabólicos.
Posteriormente, através do novo modelo matemático, simulou-se o comportamento do osso em
cenários diferentes (doença, tratamento e estímulos mecânicos). Os resultados gerados pelo
novo modelo são comparados com os resultados dos modelos revistos na presente tese. Estas
comparações mostram resultados qualitativamente semelhantes entre o novo modelo e os modelos dos outros autores.
Bone is a living tissue constantly renewing itself as it is capable to adapt its geometry and internal structure in response to mechanical and physiological demands. Bone adaptation consists of reabsorption of old bone and formation of new one. This adaptation is also called bone remodeling. The goal of bone remodeling is to prevent the accumulation of microdamage to minimize the possibility of bone fracture and keep mineral homeostasis of bone. The bone remodeling mechanism includes complex processes that depend on factors like biochemical interactions, coordination of the basic multicellular unit (BMU) activities and the feedback from mechanical stimuli. The BMU is composed by osteoblasts and osteoclasts. Achieving new insights about the bone remodeling machinery has been curtailed by the complexity of this mechanism. In vivo or in vitro tests alone fail to provide new hypotheses. To better understand this mechanism, it is useful to develop new mathematical models for the integration of theoretical knowledge in mathematical expressions that allow us to understand the most relevant interactions and to develop virtual simulations to formulate new hypotheses. I present in this work, a review of some mathematical and computational models for the bone remodeling proposed to date. There are two areas of study for development of mathematical models: a mechanical level and metabolic level. Mathematical models developed at these two levels can aim at describing the behavior and function of bone remodeling. After that, a new mathematical model will be created and will includes mechanical and metabolic factors. Moreover, the simulation of different scenario like disease, treatment and mechanical stimulation will be simulated by the new mathematical model. The results generated by the new model are compared with the results of the models reviewed in this thesis. These comparisons show that the results are qualitatively similar between the new model and the model of the other authors.
Bone is a living tissue constantly renewing itself as it is capable to adapt its geometry and internal structure in response to mechanical and physiological demands. Bone adaptation consists of reabsorption of old bone and formation of new one. This adaptation is also called bone remodeling. The goal of bone remodeling is to prevent the accumulation of microdamage to minimize the possibility of bone fracture and keep mineral homeostasis of bone. The bone remodeling mechanism includes complex processes that depend on factors like biochemical interactions, coordination of the basic multicellular unit (BMU) activities and the feedback from mechanical stimuli. The BMU is composed by osteoblasts and osteoclasts. Achieving new insights about the bone remodeling machinery has been curtailed by the complexity of this mechanism. In vivo or in vitro tests alone fail to provide new hypotheses. To better understand this mechanism, it is useful to develop new mathematical models for the integration of theoretical knowledge in mathematical expressions that allow us to understand the most relevant interactions and to develop virtual simulations to formulate new hypotheses. I present in this work, a review of some mathematical and computational models for the bone remodeling proposed to date. There are two areas of study for development of mathematical models: a mechanical level and metabolic level. Mathematical models developed at these two levels can aim at describing the behavior and function of bone remodeling. After that, a new mathematical model will be created and will includes mechanical and metabolic factors. Moreover, the simulation of different scenario like disease, treatment and mechanical stimulation will be simulated by the new mathematical model. The results generated by the new model are compared with the results of the models reviewed in this thesis. These comparisons show that the results are qualitatively similar between the new model and the model of the other authors.
Description
Keywords
Remodelação óssea Modelos matemáticos Tecido ósseo BMU Factores metabólicos Factores mecânicos Bone remodeling Mathematical models Bone tissue Metabolic factors Mechanical factors