Planejamento e construção de mecanismo para ensaio de desgaste superficial e análise de falhas em tribossistema protético articular de quadril
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Data
2018-12-17
Autores
Ribeiro, Rubens
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Os problemas associados às falhas protéticas e cirurgias de revisão aumentaram muito desde que a substituição total da articulação passou a ser aplicada também a pacientes mais jovens e mais ativos, portanto, a necessidade de resolver ou reduzir os problemas relacionados ao desgaste é de suma importância. Partindo-se dessa premissa, decidiu-se por projetar, fabricar e validar uma máquina de ensaio de desgaste do tipo acoplamento orbital, capaz de realizar o ensaio de desgaste de Prótese Total de Quadril (PTQ), obedecendo aos parâmetros de carga e movimento (Flexão/Extensão, Adução/Abdução), estabelecidos pela Norma ABNT NBR ISO 14242-3. Após a validação, foi realizado o ensaio de uma amostra composta de uma cabeça femoral de 28 mm de diâmetro de aço inox ASTM F138 e acetábulo de polietileno convencional (UHMWPE). O ensaio teve a duração de um milhão de ciclos (aproximadamente 12 dias), equivalente a aproximadamente um ano de uso da prótese in vivo e teve duas avaliações de perda de massa e volume ao longo do ensaio. Os resultados obtidos da taxa média de perda de massa e volume por milhão de ciclos, foram compatíveis com os resultados apresentados por outros autores. A avaliação do desgaste sofrido pelo componente acetabular (análise visual e microscópica) e a análise morfológica das partículas geradas pelo desgaste via MEV, forneceram informações importantes para melhor interpretar os mecanismos de desgastes (abrasão, adesão e fadiga) ocorridos durante o ensaio tribológico. É fato que esses mecanismos de desgaste, comprometem a vida útil de um tribossistema protético articular de quadril, interferindo na longevidade da articulação protética ou muitas vezes levando à total falência do implante. Os resultados apresentados pelo equipamento construído em termos de carregamento e movimento estiveram dentro dos parâmetros estabelecidos pela Norma de Referência, bem como os resultados de desgaste provocado pela máquina (perda de massa e volume do acetábulo), foram compatíveis com os resultados de outros autores.
The problems associated with prosthetic failure and revision surgery have increased greatly since total joint replacement has also been applied to younger and more active patients, so the need to resolve or reduce wear-related problems is of paramount importance. Based on this premise, it was decided to design, manufacture and validate a wear test machine of the orbital coupling type, capable of performing the Total Hip Prosthesis (PTQ) wear test, according to load and movement parameters ( Flexion / Extension, Adduction / Abduction), established by the Standard ABNT NBR ISO 14242-3. After validation, a sample composed of a 28 mm diameter femoral head of ASTM F138 stainless steel and conventional polyethylene acetabulum (UHMWPE) was performed. The assay lasted for one million cycles (approximately 12 days), equivalent to approximately one year of use of the prosthesis in vivo and had two mass and volume loss evaluations throughout the trial. The results obtained from the average loss rate of mass and volume per million cycles were compatible with the results presented by other authors. The evaluation of the wear of the acetabular component (visual and microscopic analysis) and the morphological analysis of the particles generated by the MEV wear, provided important information to better interpret the mechanisms of wear (abrasion, adhesion and fatigue) that occurred during the tribological test. It is a fact that these wear mechanisms compromise the useful life of a hip joint prosthetic tribosystem, interfering in the longevity of the prosthetic joint or often leading to total implant failure. The results presented by the equipment constructed in terms of loading and movement were within the parameters established by the Reference Norm, as well as, the results of machine-induced wear (loss of mass and volume of the acetabulum), were compatible with the results of other authors.
The problems associated with prosthetic failure and revision surgery have increased greatly since total joint replacement has also been applied to younger and more active patients, so the need to resolve or reduce wear-related problems is of paramount importance. Based on this premise, it was decided to design, manufacture and validate a wear test machine of the orbital coupling type, capable of performing the Total Hip Prosthesis (PTQ) wear test, according to load and movement parameters ( Flexion / Extension, Adduction / Abduction), established by the Standard ABNT NBR ISO 14242-3. After validation, a sample composed of a 28 mm diameter femoral head of ASTM F138 stainless steel and conventional polyethylene acetabulum (UHMWPE) was performed. The assay lasted for one million cycles (approximately 12 days), equivalent to approximately one year of use of the prosthesis in vivo and had two mass and volume loss evaluations throughout the trial. The results obtained from the average loss rate of mass and volume per million cycles were compatible with the results presented by other authors. The evaluation of the wear of the acetabular component (visual and microscopic analysis) and the morphological analysis of the particles generated by the MEV wear, provided important information to better interpret the mechanisms of wear (abrasion, adhesion and fatigue) that occurred during the tribological test. It is a fact that these wear mechanisms compromise the useful life of a hip joint prosthetic tribosystem, interfering in the longevity of the prosthetic joint or often leading to total implant failure. The results presented by the equipment constructed in terms of loading and movement were within the parameters established by the Reference Norm, as well as, the results of machine-induced wear (loss of mass and volume of the acetabulum), were compatible with the results of other authors.
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Palavras-chave
Ensaio de desgaste, Prótese de quadril, Tribossistema protético, Ensaio destrutivo, Wear test, Hip prosthesis, Prosthetic tribosystem, Destructive test