Biomechanical analysis of surgical treatments of the cervical spine

Detalhes bibliográficos
Autor(a) principal: Rodrigues, Diana Rebecca Esteves Cardoso Gavazzo
Data de Publicação: 2011
Tipo de documento: Dissertação
Idioma: eng
Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
Texto Completo: http://hdl.handle.net/10773/8366
Resumo: The main objective of this thesis was to study the biomechanical implications related to different surgical procedures for decompressing the intervertebral discs in the cervical spine. The different surgical techniques were evaluated so as to assess how load transfer to the adjacent vertebrae would be affected, thereby ascertaining the potential risks of failure of these vertebrae when compared to the vertebrae in the native (healthy) state. For this purpose an initial analysis of the cervical spine was performed, specifically on the C4-C6 segment, from an anatomical, biomechanical and pathological point of view. An analysis of surgical reconstructive processes was also carried out, with particular focus on the two procedures known as arthrodesis and arthroplasty. Finite element models were then developed from CT images obtained from a healthy male patient, with the purpose of comparing the surgical cases of arthrodesis and arthroplasty to the native case. For these tests the selected implants were the Fidji PEEK cage (Zimmer, Inc) for the arthrodesis case and the ProDisc-C (Synthes, Inc.) for the arthroplasty case. The different models generated from medical CT imaging were reconstructed with the help of 3D modelling and finite element software and submitted to loading conditions that simulated the weight of the human head in the anatomical (upright) position. The results obtained for each model enabled the evaluation, and therefore the comparison, of the alterations in load transfer from one model too another. These alterations were determined through the measurement of the variations in the principal strain values in the cortical bone of vertebrae C5 and C6, adjacent to the implant, and in vertebra C4, which was positioned directly above vertebra C5. Compressive strain values were also analysed in the trabecular bone for all three vertebrae. The principal strain values in the anterior vertebral body of vertebrae C5 and C6, obtained from the numerical models developed, were compared with the respective results obtained from the experimental models subsequently used in this study. In addition to the numerical models developed, experimental models of the C5-C6 segment in rigid polyurethane foam were created. The different surgical techniques (arthroplasty and arthrodesis) were performed in-vitro. The purpose behind the development of these models was to ascertain the extent to which the results obtained for the numerical models could be experimentally replicated. Alterations in load transfer in these models was registered by means of rosette strain gauges placed in the anterior region of the vertebrae, allowing the evaluation of the principal strain values on the model’s surface. These experimental models were submitted to the same loading conditions as the numerical models. A high correlation between the principal strain values was obtained when comparing the numerical models with the experimental models, thus revealing the ability of the numerical models to recreate the mechanical behaviour of the experimental models. The comparison made between the native numerical model (in which mechanical bone properties had not been simplified) and the model where mechanical properties were discretized, into cortical and trabecular bone properties, revealed differences that should not be overlooked. When comparing implanted models with the native model an increase in principal strain values of cortical and trabecular bone, particularly in the lateral areas of the vertebral body were revealed, relatively to the native model. On average these increases were lower in the cortical bone for the arthroplasty case than in the arthrodesis case, but higher in the trabecular bone. Thus, it is concluded that both surgical techniques contribute to the increase of mechanical strain on the vertebrae adjacent to the implants, and thus possibly increase the risk of failure of the bone structure due to fatigue.
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spelling Biomechanical analysis of surgical treatments of the cervical spineEngenharia mecânicaBiomecânicaArtroplastiaImplantes ortopédicosColuna vertebralThe main objective of this thesis was to study the biomechanical implications related to different surgical procedures for decompressing the intervertebral discs in the cervical spine. The different surgical techniques were evaluated so as to assess how load transfer to the adjacent vertebrae would be affected, thereby ascertaining the potential risks of failure of these vertebrae when compared to the vertebrae in the native (healthy) state. For this purpose an initial analysis of the cervical spine was performed, specifically on the C4-C6 segment, from an anatomical, biomechanical and pathological point of view. An analysis of surgical reconstructive processes was also carried out, with particular focus on the two procedures known as arthrodesis and arthroplasty. Finite element models were then developed from CT images obtained from a healthy male patient, with the purpose of comparing the surgical cases of arthrodesis and arthroplasty to the native case. For these tests the selected implants were the Fidji PEEK cage (Zimmer, Inc) for the arthrodesis case and the ProDisc-C (Synthes, Inc.) for the arthroplasty case. The different models generated from medical CT imaging were reconstructed with the help of 3D modelling and finite element software and submitted to loading conditions that simulated the weight of the human head in the anatomical (upright) position. The results obtained for each model enabled the evaluation, and therefore the comparison, of the alterations in load transfer from one model too another. These alterations were determined through the measurement of the variations in the principal strain values in the cortical bone of vertebrae C5 and C6, adjacent to the implant, and in vertebra C4, which was positioned directly above vertebra C5. Compressive strain values were also analysed in the trabecular bone for all three vertebrae. The principal strain values in the anterior vertebral body of vertebrae C5 and C6, obtained from the numerical models developed, were compared with the respective results obtained from the experimental models subsequently used in this study. In addition to the numerical models developed, experimental models of the C5-C6 segment in rigid polyurethane foam were created. The different surgical techniques (arthroplasty and arthrodesis) were performed in-vitro. The purpose behind the development of these models was to ascertain the extent to which the results obtained for the numerical models could be experimentally replicated. Alterations in load transfer in these models was registered by means of rosette strain gauges placed in the anterior region of the vertebrae, allowing the evaluation of the principal strain values on the model’s surface. These experimental models were submitted to the same loading conditions as the numerical models. A high correlation between the principal strain values was obtained when comparing the numerical models with the experimental models, thus revealing the ability of the numerical models to recreate the mechanical behaviour of the experimental models. The comparison made between the native numerical model (in which mechanical bone properties had not been simplified) and the model where mechanical properties were discretized, into cortical and trabecular bone properties, revealed differences that should not be overlooked. When comparing implanted models with the native model an increase in principal strain values of cortical and trabecular bone, particularly in the lateral areas of the vertebral body were revealed, relatively to the native model. On average these increases were lower in the cortical bone for the arthroplasty case than in the arthrodesis case, but higher in the trabecular bone. Thus, it is concluded that both surgical techniques contribute to the increase of mechanical strain on the vertebrae adjacent to the implants, and thus possibly increase the risk of failure of the bone structure due to fatigue.Procurou-se especificamente avaliar como cada uma das diferentes técnicas cirúrgicas altera a transferência de carga as vértebras adjacentes, aferindo assim potenciais riscos de falência destas quando comparadas com a situação das vértebras no estado nativo (saudável). Para o efeito, numa primeira fase procurou-se realizar uma naálise detalhada a coluna cervical, especificamente ao segmento C4-C6, na sua vertente anatómica, biomecânica e patológica, assim como dos processos cirúrgicos de reconstrução com especial enfoque na artrodese e artroplastia cervical. Numa fase posterior procedeu-se ao desenvolvimento de modelos numéricos de elementos finitos a partir de imagens de TAC de um paciente saudável, com o propósito de comparar as técnicas de artroplastia e artrodese com a situação nativa. Para estas análises foram seleccionados os implantes Fidji PEEK cage (Zimmer, Inc) para a técnica da artrodese, e ProDisc-C (Synthes, Inc) para a técnica da artroplastia. Estes diferentes modelos, gerados a partir das imagens médicas de TAC, foram reconstruídos com o auxílio de softwares de modelação 3D e de elemento finitos, e submetidos a condiç oes de cargas idênticas, correspondente ao peso da cabeça humana na postura anatómica. Os resultados obtidos com estes modelos permitiram avaliar de forma comparativa as alterações de transferência de carga através das deformações principais no osso cortical das vértebras C5-C6 imediatamente adjacente aos implantes, assim como na vértebra C4 do segmento anexo. Em complemento destas deformações foram também analisadas as deformações de compressão no osso esponjoso das mesmas vértebras. As deformações principais no cortex anterior das vértebras C5-C6 dos modelos experimentais desenvolvidos foram comparadas com os resultados obtidos nos modelos numéricos correspondentes criados neste estudo. Em complemento aos modelos numéricos anteriores, desenvolveram-se modelos experimentais do segmento C5-C6, em espuma rígida de poliuretano, onde as diferentes técnicas cirúrgicas (artrodese e artroplastia) foram implementadas através de cirurgias “in-vitro”. O desenvolvimento destes modelos pretendeu aferir até que ponto os resultados obtidos nos modelos numéicos se reproduziam experimentalmente. As alterações de transferência de carga nestes modelos foram realizadas com recurso a rosetas de extensómetros colocadas na região anterior das vértebras, permitindo a avaliação das deformações principais na sua superfície. Estes modelos foram submetidos ao mesmo caso de carga dos modelos numéricos. Um elevado valor de correlação entre as deformações principais foi obtido na comparação dos modelos numéricos com os modelos experimentais, revelando uma boa capacidade dos modelos numéricos replicarem o comportamento mecânico dos modelos experimentais. Os resultados obtidos na comparação do modelo numérico nativo com o modelo em que as propriedades mecânicas foram discretizadas, em osso cortical e esponjoso, revelaram diferenças não desprezáveis. Os resultados obtidos entre os diferentes modelos implantados e o modelo nativo revelaram aumentos das deformações no osso cortical e esponjoso, em particular nas zonas laterais aos implantes, relativamente ao modelo nativo. Em média estes aumentos foram inferiores na técnica da artroplastia relativamente a artrodese no osso cortical e foram superiores no osso esponjoso. Assim, conclui-se que as ambas as técnicas cirúrgicas contribuem para o agravar da solicitação mecânica sobre as vértebras adjacentes aos implantes, e desta forma possivelmente potenciar o risco de falência por efeito do processo de fadiga.Universidade de Aveiro2012-04-27T16:12:57Z2011-01-01T00:00:00Z2011info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesisapplication/pdfhttp://hdl.handle.net/10773/8366engRodrigues, Diana Rebecca Esteves Cardoso Gavazzoinfo:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2024-02-22T11:14:09Zoai:ria.ua.pt:10773/8366Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-20T02:45:33.796673Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse
dc.title.none.fl_str_mv Biomechanical analysis of surgical treatments of the cervical spine
title Biomechanical analysis of surgical treatments of the cervical spine
spellingShingle Biomechanical analysis of surgical treatments of the cervical spine
Rodrigues, Diana Rebecca Esteves Cardoso Gavazzo
Engenharia mecânica
Biomecânica
Artroplastia
Implantes ortopédicos
Coluna vertebral
title_short Biomechanical analysis of surgical treatments of the cervical spine
title_full Biomechanical analysis of surgical treatments of the cervical spine
title_fullStr Biomechanical analysis of surgical treatments of the cervical spine
title_full_unstemmed Biomechanical analysis of surgical treatments of the cervical spine
title_sort Biomechanical analysis of surgical treatments of the cervical spine
author Rodrigues, Diana Rebecca Esteves Cardoso Gavazzo
author_facet Rodrigues, Diana Rebecca Esteves Cardoso Gavazzo
author_role author
dc.contributor.author.fl_str_mv Rodrigues, Diana Rebecca Esteves Cardoso Gavazzo
dc.subject.por.fl_str_mv Engenharia mecânica
Biomecânica
Artroplastia
Implantes ortopédicos
Coluna vertebral
topic Engenharia mecânica
Biomecânica
Artroplastia
Implantes ortopédicos
Coluna vertebral
description The main objective of this thesis was to study the biomechanical implications related to different surgical procedures for decompressing the intervertebral discs in the cervical spine. The different surgical techniques were evaluated so as to assess how load transfer to the adjacent vertebrae would be affected, thereby ascertaining the potential risks of failure of these vertebrae when compared to the vertebrae in the native (healthy) state. For this purpose an initial analysis of the cervical spine was performed, specifically on the C4-C6 segment, from an anatomical, biomechanical and pathological point of view. An analysis of surgical reconstructive processes was also carried out, with particular focus on the two procedures known as arthrodesis and arthroplasty. Finite element models were then developed from CT images obtained from a healthy male patient, with the purpose of comparing the surgical cases of arthrodesis and arthroplasty to the native case. For these tests the selected implants were the Fidji PEEK cage (Zimmer, Inc) for the arthrodesis case and the ProDisc-C (Synthes, Inc.) for the arthroplasty case. The different models generated from medical CT imaging were reconstructed with the help of 3D modelling and finite element software and submitted to loading conditions that simulated the weight of the human head in the anatomical (upright) position. The results obtained for each model enabled the evaluation, and therefore the comparison, of the alterations in load transfer from one model too another. These alterations were determined through the measurement of the variations in the principal strain values in the cortical bone of vertebrae C5 and C6, adjacent to the implant, and in vertebra C4, which was positioned directly above vertebra C5. Compressive strain values were also analysed in the trabecular bone for all three vertebrae. The principal strain values in the anterior vertebral body of vertebrae C5 and C6, obtained from the numerical models developed, were compared with the respective results obtained from the experimental models subsequently used in this study. In addition to the numerical models developed, experimental models of the C5-C6 segment in rigid polyurethane foam were created. The different surgical techniques (arthroplasty and arthrodesis) were performed in-vitro. The purpose behind the development of these models was to ascertain the extent to which the results obtained for the numerical models could be experimentally replicated. Alterations in load transfer in these models was registered by means of rosette strain gauges placed in the anterior region of the vertebrae, allowing the evaluation of the principal strain values on the model’s surface. These experimental models were submitted to the same loading conditions as the numerical models. A high correlation between the principal strain values was obtained when comparing the numerical models with the experimental models, thus revealing the ability of the numerical models to recreate the mechanical behaviour of the experimental models. The comparison made between the native numerical model (in which mechanical bone properties had not been simplified) and the model where mechanical properties were discretized, into cortical and trabecular bone properties, revealed differences that should not be overlooked. When comparing implanted models with the native model an increase in principal strain values of cortical and trabecular bone, particularly in the lateral areas of the vertebral body were revealed, relatively to the native model. On average these increases were lower in the cortical bone for the arthroplasty case than in the arthrodesis case, but higher in the trabecular bone. Thus, it is concluded that both surgical techniques contribute to the increase of mechanical strain on the vertebrae adjacent to the implants, and thus possibly increase the risk of failure of the bone structure due to fatigue.
publishDate 2011
dc.date.none.fl_str_mv 2011-01-01T00:00:00Z
2011
2012-04-27T16:12:57Z
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dc.identifier.uri.fl_str_mv http://hdl.handle.net/10773/8366
url http://hdl.handle.net/10773/8366
dc.language.iso.fl_str_mv eng
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dc.publisher.none.fl_str_mv Universidade de Aveiro
publisher.none.fl_str_mv Universidade de Aveiro
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