Novo método de avaliação de desgaste de componente de polietileno de próteses totais de joelho
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Citações na Scopus
Tipo de produção
Dissertação
Data
2017
Autores
Mendes, G. C.
Orientador
Ortega, Fernando dos Santos
Periódico
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ISSN da Revista
Título de Volume
Citação
MENDES, G. C. Novo método de avaliação de desgaste de componente de polietileno de próteses totais de joelho. 2017. 98 f. Dissertação (Mestrado em Engenharia Mecânica) - Centro Universitário FEI, São Bernardo do Campo, 2017. Disponível em: . Acesso em: 29 ago. 2018.
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Palavras-chave
Cerâmica,Gelcasting
Resumo
A Artroplastia total do joelho é um procedimento de reconstrução da superfície articular do joelho, no qual uma prótese é implantada. Esta prótese eventualmente falha e, por isso, necessita ser substituída em uma cirurgia de revisão. A articulação do joelho é a maior articulação do corpo humano e é considerada uma articulação sinovial. Diversas patologias levam à necessidade de uma cirurgia primária. Pode-se afirmar também, que a articulação do
joelho possui uma biomecânica complexa que acarreta uma combinação de movimentos relativos entre as superfícies articulares de deslizamento e rolamento. Entre os materiais utilizados nas próteses de joelho o polietileno de alto peso molecular (UHMWPE) será foco do trabalho pois a falha do componente se deve em grande parte à falha do polietileno. A degradação do componente de polietileno pode ocorrer devido aos modos de desgaste conhecidos da Tribologia de adesão e abrasão, mas também devido a fadiga e fratura do material em virtude da solicitação. Em 1983, foi desenvolvido um método de análise de componentes recuperados, conhecido como Método Hood. Trinta anos passados, muitos métodos foram desenvolvidos a partir dele, sendo identificadas algumas fontes de erro no método de Hood e em suas variações. A partir daí, foi desenvolvida ferramenta em conjunto com o laboratório de
bioengenharia da Universidade de Newcastle-UK, a fim de auxiliar o avaliador na obtenção da área total projetada e da porcentagem de área danificada. Foi definida uma escala de severidade para que as porcentagens de áreas danificadas fossem multiplicadas e um valor de dano seja obtido. As imagens de componentes foram enviadas pela Universidade de Newcastle e analisadas pelo método, sendo comparadas com a respectiva pontuação obtida no método Hood.
Ao correlacioná-las com as variáveis de Tempo in vivo e o índice de massa corporal, detectouse,
via repetibilidade da avaliação, que a concordância entre avaliadores aumentou significativamente. Não houve correlação entre a escala de dano obtida e o Tempo in vivo e o Indice de massa corporal. O método proposto apresenta menor variação da obtenção da área danificada e área total, porém a qualidade das imagens comprometeu os resultados e apontou para a necessidade de desenvolvimento de um método de aquisição e processamento de
imagens.
Total Knee Arthroplasty is a surgical procedure for reconstruction of the knee joint surface, which a total knee prosthesis is implanted. This prosthesis eventually fails and needs to be replaced in a revision surgery. The knee joint is the largest joint of the human body and is considered a synovial joint. Several pathologies lead to a primary surgery. It can also be stated that the knee joint has some complex biomechanics that results in a combination of relative movements between the sliding and rolling of joint surfaces. Among the materials used in knee prostheses, Ultra High Molecular Weight Polyethylene (UHMWPE) will be the focus of the work since the failure of the prostheses can be attributed to the wear of the PE component. Degradation of the PE component can be caused by the wear modes of Tribology of adhesion and abrasion, but also as a result of fatigue and fracture of the material. In 1983, a method of wear assessment of retrieved Polyethylene components was developed that became known as the Hood Method and thirty years later, many variations of Hood s method were developed. Some sources of error were identified in the Hood method and its variations. A Software application was developed in a partnership with the bioengineering laboratory of the University of Newcastle-UK to assist the evaluator in obtaining the total projected area and the percentage of damaged area. A severity scale has been defined to be multiplied with percentages of damaged areas to obtain a damage value. The images of retrieved components were sent by the University of Newcastle and were analyzed by the method and compared with the Hood s score and correlated with the variables Time in vivo and body mass index. The repeatability of the assessment and the agreement among the evaluators increased significantly. There was no correlation between the score of damage obtained and the variables Time "in vivo" and Body Mass Index. The proposed method presents more accuracy and precision to obtain total area and damage area, but the quality of the images jeopardizes the results and lead to the need of a method of image acquisition and processing.
Total Knee Arthroplasty is a surgical procedure for reconstruction of the knee joint surface, which a total knee prosthesis is implanted. This prosthesis eventually fails and needs to be replaced in a revision surgery. The knee joint is the largest joint of the human body and is considered a synovial joint. Several pathologies lead to a primary surgery. It can also be stated that the knee joint has some complex biomechanics that results in a combination of relative movements between the sliding and rolling of joint surfaces. Among the materials used in knee prostheses, Ultra High Molecular Weight Polyethylene (UHMWPE) will be the focus of the work since the failure of the prostheses can be attributed to the wear of the PE component. Degradation of the PE component can be caused by the wear modes of Tribology of adhesion and abrasion, but also as a result of fatigue and fracture of the material. In 1983, a method of wear assessment of retrieved Polyethylene components was developed that became known as the Hood Method and thirty years later, many variations of Hood s method were developed. Some sources of error were identified in the Hood method and its variations. A Software application was developed in a partnership with the bioengineering laboratory of the University of Newcastle-UK to assist the evaluator in obtaining the total projected area and the percentage of damaged area. A severity scale has been defined to be multiplied with percentages of damaged areas to obtain a damage value. The images of retrieved components were sent by the University of Newcastle and were analyzed by the method and compared with the Hood s score and correlated with the variables Time in vivo and body mass index. The repeatability of the assessment and the agreement among the evaluators increased significantly. There was no correlation between the score of damage obtained and the variables Time "in vivo" and Body Mass Index. The proposed method presents more accuracy and precision to obtain total area and damage area, but the quality of the images jeopardizes the results and lead to the need of a method of image acquisition and processing.