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A artroplastia total da anca (ATQ) é uma técnica cirúrgica bem-sucedida que pode ser utilizada para o tratamento eficaz de fraturas do colo do fémur, osteoartrite, tumores, necrose vascular, falha na fixação interna, displasia do desenvolvimento e artrite reumatoide. O grande número de operações de revisão realizadas todos os anos em resultado de falha do implante realça a necessidade de uma melhor compreensão biomecânica do sistema de implante femoral. Esta dissertação estuda como próteses
femorais se comportam quando feitas de diferentes materiais e como ocorre a deformação quando sujeita a uma carga típica. Para realizar este estudo realizaram-se duas aproximações distintas, uma numérica e outra experimental. Por digitalização da geometria da haste é obtido um modelo virtual da haste anatomicamente adaptada no software SolidWorks. A haste final foi impressa em 3D no laboratório FABLAB com PLA. Já o suporte da mesma foi fabricada por maquinagem numa fresadora CNC no laboratório de tecnologia mecânica. Foi utilizado o software de elementos finitos (ANSYS) para realizar as simulações numéricas. A geometria do fémur, tanto para os estudos experimentais como para os estudos de elementos finitos, foi baseada no fémur médio esquerdo. Posteriormente, foi realizado um ensaio de compressão no laboratório
de resistência dos materiais com o propósito de validar o campo de deformações medido com o sistema implementado, tendo como referência o campo de deformações obtido pelo método de elementos finitos. Na análise desenvolvida utilizou-se a técnica da Correlação Digital de Imagem por permitir a medição do campo de deformações com elevada resolução na região do implante. A partir das propriedades mecânicas medidas, para as mesmas condições de carregamento e de fronteira determinaram-se os campos de
deslocamento e deformação. A comparação da simulação numérica com os obtidos por via experimental permitiu validar as propriedades mecânicas determinadas a partir das medições computacionais, onde confirma-se a potencialidade deste tipo de ensaios para medições de campos de deslocamento e deformações.
Total hip arthroplasty (THA) is a successful surgical technique that can be used for the effective treatment of femoral neck fractures, osteoarthritis, tumors, vascular necrosis, internal fixation failure, developmental dysplasia and rheumatoid arthritis. The large number of revision operations performed every year as a result of implant failure high-lights the need for a better biomechanical understanding of the femoral implant system. This dissertation studies how femoral prostheses behave when made from different materials and how deformation occurs when subjected to a typical load. To carry out this study, two different approaches were taken, one numerical and the other experimental. By digitizing the stem geometry, a virtual model of the anatomically adapted stem is obtained in SolidWorks software. The final stem was 3D printed in the FABLAB laboratory using PLA. Its support was manufactured by machining on a CNC milling machine. Finite element software (ANSYS) was used to carry out the numerical simulations. The geometry of the femur, for both the experimental and finite element studies, was based on the left middle femur. Subsequently, a compression test was carried out in the strength of materials laboratory in order to validate the deformation field measured with the implemented system, with the deformation field obtained by the finite element method as a reference. The Digital Image Correlation technique was used in the analysis because it allows the deformation field to be measured with high resolution in the implant region. Based on the mechanical properties measured, the displacement and deformation fields were determined for the same loading and boundary conditions. Comparison of the numerical simulation with the experimental results allowed the mechanical properties determined from the computational measurements to be validated, confirming the potential of this type of test for measuring displacement and deformation fields.
Total hip arthroplasty (THA) is a successful surgical technique that can be used for the effective treatment of femoral neck fractures, osteoarthritis, tumors, vascular necrosis, internal fixation failure, developmental dysplasia and rheumatoid arthritis. The large number of revision operations performed every year as a result of implant failure high-lights the need for a better biomechanical understanding of the femoral implant system. This dissertation studies how femoral prostheses behave when made from different materials and how deformation occurs when subjected to a typical load. To carry out this study, two different approaches were taken, one numerical and the other experimental. By digitizing the stem geometry, a virtual model of the anatomically adapted stem is obtained in SolidWorks software. The final stem was 3D printed in the FABLAB laboratory using PLA. Its support was manufactured by machining on a CNC milling machine. Finite element software (ANSYS) was used to carry out the numerical simulations. The geometry of the femur, for both the experimental and finite element studies, was based on the left middle femur. Subsequently, a compression test was carried out in the strength of materials laboratory in order to validate the deformation field measured with the implemented system, with the deformation field obtained by the finite element method as a reference. The Digital Image Correlation technique was used in the analysis because it allows the deformation field to be measured with high resolution in the implant region. Based on the mechanical properties measured, the displacement and deformation fields were determined for the same loading and boundary conditions. Comparison of the numerical simulation with the experimental results allowed the mechanical properties determined from the computational measurements to be validated, confirming the potential of this type of test for measuring displacement and deformation fields.
Descrição
Palavras-chave
Biomecânica Artroplastia da anca Prótese de anca Fémur Elementos finitos Correlação digital de imagens