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Ayres, Gustavo Garcia Francisco Algéos. "Meniscal injury associated with cranial cruciate ligament rupture in dogs : a retrospective case study." Master's thesis, Universidade de Lisboa, Faculdade de Medicina Veterinária, 2017. http://hdl.handle.net/10400.5/14654.
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Dissertação de Mestrado Integrado em Medicina VeterináriaCranial cruciate ligament (CrCL) rupture is the most common orthopaedic disease in dogs and medial meniscal injury is very often associated with this condition. Concurrent meniscal damage can be diagnosed at the time of the stifle stabilization surgery, however, post-surgical meniscal tears can also develop and should be taken into account. This study incorporates a bibliographic review about medial meniscal tears associated with CrCL ruptures and a retrospective study of 22 stifles from 20 different dogs which were diagnosed with CrCL rupture and which meniscal integrity was evaluated. A craniomedial arthrotomy of the stifle was performed in all cases in order to diagnose meniscal damage. Meniscal tears were treated surgically in order to remove all of the damaged tissue and preserve as much healthy meniscal tissue as possible. 10 out of 22 stifles were diagnosed with concurrent meniscal injury during this study (45%). The rate of concurrent meniscal injury of this study is comparable to the previous published ones. In this retrospective study and bibliographic review it is concluded that meniscal pathology is a very common disease associated with CrCL rupture which should be treated since it causes chronic lameness, progression of osteoarthritis and pain to the patient.
RESUMO - LESÕES DE MENISCO ASSOCIADAS À ROTURA DO LIGAMENTO CRUZADO CRANIAL EM CÃES: ESTUDO DE CASOS RETROSPETIVO - A rotura do ligamento cruzado cranial (LCC) é a doença ortopédica mais comum em cães e a lesão do menisco medial é muito comumente associada a esta condição. Danos no menisco podem ser diagnosticadas aquando da cirurgia para estabilização do joelho, no entanto, lesões de menisco pós-cirúrgicas também se podem desenvolver e devem ser tidas em conta. Este estudo incorpora uma revisão bibliográfica sobre lesões de menisco associadas à rotura do LCC e um estudo retrospetivo de 22 joelhos de 20 cães diferentes aos quais foi diagnosticada a rotura do LCC e aos quais a integridade do menisco foi avaliada. Uma artrotomia craniomedial de joelho foi feita em todos os casos para diagnosticar lesões no menisco medial. As lesões identificadas foram tratadas cirurgicamente de modo a remover todo o tecido alterado e preservar tanto quanto possível o tecido saudável. Dos 22 joelhos, 10 foram diagnosticados com lesões de menisco (45%). Este valor pode ser comparável ao reportado por estudos publicados previamente. Neste estudo retrospetivo e revisão bibliográfica pode ser concluído que as lesões de menisco são uma condição associada à rotura do LCC e que deve ser tratada visto provocar claudicação crónica, dor e progressão da osteoartrite.
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Masferrer, Pino Ángel. "¿Es la capsulodesis la clave para evitar la extrusión meniscal después de un trasplante? Estudio clínico, radiológico y anatómico." Doctoral thesis, Universitat Autònoma de Barcelona, 2020. http://hdl.handle.net/10803/671263.
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Aquesta tesi doctoral busca investigar si l'aplicació de la tècnica quirúrgica anomenada com "Capsulodesis" pot ser clau per evitar l'extrusió meniscal després d'un trasplantament meniscal lateral de genoll. A través d'un examen clínic, radiològic i anatòmic, cada un dels articles que composen aquesta tesi es va centrar en l'estudi d'un dels següents tres punts clau en el trasplantament meniscal al·logènic (TMA):
1. Comparar els resultats radiològics (en termes d'extrusió meniscal) i els resultats funcionals dels trasplantaments de loempelt de menisc lateral (TMA) realitzats mitjançant una tècnica de fixació òssia (barra òssia) o mitjançant una tècnica de fixació de teixits tous (túnels transóseos) després de realitzar prèviament una capsulodesis.
2. Comparar la quantitat d'extrusió meniscal després d'un TMA lateral realitzat amb una tècnica només de sutura, amb o sense capsulodesis associada, a més de comparar els resultats funcionals entre les dues tècniques.
3. Analitzar, quantificar i redefinir l'anatomia de les fixacions perifèriques de el cos de l'menisc lateral per comprendre millor com aquestes estructures podrien tenir un paper en la prevenció de l'extrusió meniscal i com podria aplicar-se a les tècniques quirúrgiques.Esta tesis doctoral busca investigar si la aplicación de la técnica quirúrgica denominada como "Capsulodesis" puede ser clave para evitar la extrusión meniscal después de un trasplante meniscal lateral de rodilla. A través de un examen clínico, radiológico y anatómico, cada uno de los artículos que componen esta tesis se centró en el estudio de uno de los siguientes tres puntos clave en el trasplante meniscal alogénico (TMA): 1. Comparar los resultados radiológicos (en términos de extrusión meniscal) y los resultados funcionales de los trasplantes de aloinjerto de menisco lateral (TMA) realizados mediante una técnica de fijación ósea (barra ósea) o mediante una técnica de fijación de tejidos blandos (túneles transóseos) después de realizar previamente una capsulodesis. 2. Comparar la cantidad de extrusión meniscal después de un TMA lateral realizado con una técnica solamente de sutura, con o sin capsulodesis asociada, además de comparar los resultados funcionales entre ambas técnicas. 3. Analizar, cuantificar y redefinir la anatomía de las fijaciones periféricas del cuerpo del menisco lateral para comprender mejor cómo estas estructuras podrían desempeñar un papel en la prevención de la extrusión meniscal y cómo podría aplicarse a las técnicas quirúrgicas.
This doctoral thesis seeks to investigate whether the application of the surgical technique known as "Capsulodesis" can be key to avoiding meniscal extrusion after a lateral meniscal knee transplant. Through a clinical, radiological and anatomical examination, each of the articles that make up this thesis focused on the study of one of the following three key points in allogeneic meniscal transplantation (MAT): 1. Compare the radiological results (in terms of meniscal extrusion) and the functional results of lateral meniscus allograft transplantation (MAT) performed using a bone fixation technique (bone bar) or a soft tissue fixation technique (tunnels transosseous) after previously performing a capsulodesis. 2. Compare the amount of meniscal extrusion after a lateral MAT performed with a suture-only technique, with or without associated capsulodesis, in addition to comparing the functional results between both techniques. 3. Analyze, quantify, and redefine the anatomy of the peripheral attachments of the body of the lateral meniscus to better understand how these structures might play a role in preventing meniscal extrusion and how it could be applied to surgical techniques.
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Ferrari, Márcio Balbinotti. "Reparo meniscal em crianças e adolescentes : uma revisão sistemática de resultados." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/174843.
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OBJETIVO: Realizar uma revisão sistemática da literatura existente, a fim de analisar os resultados após o reparo meniscal na população pediátrica. MÉTODOS: Uma revisão sistemática foi realizada de acordo com as diretrizes PRISMA usando os Bancos de Dados de Análise Sistemática Cochrane, Registro Central Cochrane de ensaios controlados, MEDLINE Ovid e MEDLINE PubMed. Os critérios de inclusão foram os seguintes: estudos que relatam os resultados do reparo meniscal em pacientes com 18 anos ou menos, com um seguimento médio mínimo de 12 meses, idiomas português, espanhol ou inglês e estudos humanos incluindo 10 ou mais pacientes. RESULTADOS: Nossa pesquisa identificou 2534 títulos individuais. Após a aplicação dos critérios de inclusão e exclusão, foram incluídos oito estudos, avaliando 287 pacientes com lesões meniscais reparadas. Sete estudos foram classificados como nível de evidência IV e um nível III. O escore médio MINORS foi de 8,6 ± 1,4. O reparo meniscal incluiu todas as zonas meniscais e padrões de lesões. A lesão do ligamento cruzado anterior foi a lesão associada mais comum. As técnicas “inside-out” e “all-inside” foram predominantemente relatadas. A maioria dos pacientes relatou resultados bons a excelentes e teve sinais clínicos de cicatrização meniscal; as meniscectomias após reparação meniscal foram realizadas em apenas 44 casos. CONCLUSÃO: Lesões meniscais em pediatria não são incomuns. O reparo desta lesão foi associado com resultados bons a excelentes na maioria dos pacientes, independentemente do padrão de lesão, zona ou técnica. As complicações relatadas foram mínimas, no entanto, são necessários estudos de maior qualidade para confirmar os achados desta revisão sistemática. NÍVEL DE EVIDÊNCIA: Nivel IV, revisão sistemática de estudos nível III e nível IV.PURPOSE: To perform a systematic review of existing literature in order to analyze outcomes after meniscal repair in the pediatric population. METHODS: A systematic review was performed according to PRISMA guidelines using the Cochrane Database of Systematic Review, Cochrane Central Register of Controlled Trials, MEDLINE Ovid, and MEDLINE PubMed databases. Inclusion criteria were as follows: studies reporting the outcomes of meniscal repair in patients 18 years old or younger, with a minimum mean follow-up of 12 months, Portuguese, Spanish or English languages, and human studies including 10 or more patients. RESULTS: Our search identified 2534 individual titles. After application of the inclusion and exclusion criteria, 8 studies were included, evaluating 287 patients with repaired meniscal tears. Seven studies were classified as level of evidence IV and one level III. The mean MINORS score was 8.6 ± 1.4. Meniscal repair included all meniscal zones and tear patterns. Anterior cruciate ligament tear was the most common associated injury. The all-inside and inside-out techniques were predominantly reported. The majority of the patients reported good to excellent outcomes and had clinical signals of meniscal healing; meniscectomies following meniscal repair were performed in just 44 cases. CONCLUSION: Meniscal tears in pediatrics are not uncommon. Repairs of this injury were associated with good to excellent outcomes in most patients, regardless of the injury pattern, zone or technique. Reported complications were minimal, however, higher quality studies are needed to confirm the findings of this systematic review. LEVEL OF EVIDENCE: Level IV, systematic review of Level III and Level IV studies.
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Alvarellos, Jose. "Fundamental Studies of Capillary Forces in Porous Media." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5314.
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The contact angle defined by Young's equation depends on the ratio between solid and liquid surface energies. Young's contact angle is constant for a given system, and cannot explain the stability of fluid droplets in capillary tubes. Within this framework, large variations in contact angle and explained aassuming surface roughness, heterogeneity or contamination. This research explores the static and dynamic behavior of fluid droplets within capillary tubes and the variations in contact angle among interacting menisci. Various cases are considered including wetting and non-wetting gluids, droplets in inclined capillary tubes or subjected to a pressure difference, within one-dimensional and three-dimensional capillary systems, and under static or dynamic conditions (either harmonic fluid pressure or tube oscillation). The research approach is based on complementary analytical modeling (total energy formulation) and experimental techniques (microscopic observations). The evolution of meniscus curvatures and droplet displacements are studied in all cases. Analytical and experimental results show that droplets can be stable within capillary tubes even under the influence of an external force, the resulting contact angles are not constant, and bariations from Young's contact angle aare extensively justified as menisci interaction. Menisci introduce stiffness, therefore two immiscible Newtonian fluids behave as a Maxwellian fluid, and droplets can exhibit resonance or relaxation spectral features.
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Tumia, Nezar S. "The knee meniscus : investigating the regenerative potential of meniscal cartilage exposed to recombinant growth factors in vitro." Thesis, University of Aberdeen, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.430973.
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Meniscal tears are common debilitating injuries that can have dramatic consequences especially for young athletes. Healing of meniscal tears following surgical repair is essentially only feasible for tears within the peripheral vascular zone. By comparison, tears that occur within the inner avascular zone do not heal and most commonly are treated by excision. This in turn greatly increases the potential for secondary osteoarthrosis. Clearly, there is a clinical need to augment surgical techniques, extending meniscal repair to the avascular zone. In this study, monolayer cell cultures were prepared from the inner, middle, and outer zones of the lateral menisci of sheep and from humans obtained following total knee arthroplasty and partial meniscectomy. Various concentrations of Platelet Derived Growth Factor (PDGF-AB), Insulin-like Growth Factor type I (IGF-I), and basic Fibroblast Growth Factor (bFGF) were used individually to assess their effects upon cell proliferation and extracellular matrix formation. This study found that the growth factors under investigation stimulated the fibrochondrocytes, both human and sheep, in a similar dose dependent fashion, although the specifics and extent of stimulation differed for each of the growth factors, and for each species. Interestingly, fibrochondrocytes cultured from the avascular zone were stimulated in a similar fashion to those cultured from the vascular zone. The action of the growth factors was not dependent upon serum being present. Therefore, the results of this study are an encouraging first step towards enhancing the regeneration and potentially the repair of injured meniscal tissue.
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POLITO, UMBERTO. "THE MENISCUS: BASIC SCIENCE TO IMPROVE KNOWLEDGE FOR TISSUE ENGINEERING." Doctoral thesis, Università degli Studi di Milano, 2020. http://hdl.handle.net/2434/707236.
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This thesis was thought with the intent to try to fill some lacunae in the knowledge of the anatomic-dependent features of the meniscus. In particular, the study of the effects of endogenous and exogenous factors upon the development of this structure will be outlined. Endogenous factors have been considered those factors that cannot be attributed to external or experimental factors: the effect of age and growth has been investigated focusing on the variation of the, matrix components (collagen types, GAGs and decorin), cellular phenotypic modifications and meniscal morpho-functional structure, with additional focus on possible differences presented in different animal models. On the other hand, exogenous factors have been considered those factors that are in any way attributable to the external interventions operated by the experimenter or by the application of forces upon meniscus. As exogenous factors, the effects of physiologic (compression and traction to which meniscus is naturally subjected) and non-physiologic (continuous compression without flexion) forces applied to meniscus during growth were evaluated. Furthermore, the effect of hypoxia in meniscal tissue-culture was also evaluated in a neonatal committed cell population in order to assess a faster maturation of the tissue. The importance of these investigations is linked to the possible application of these notions in the field of tissue engineering of the meniscus and may improve the current knowledge on the morpho-functional effect that external factors exercise on its structure.
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Cornelius, Ryan Marks Corey. "Meniscus." [Denton, Tex.] : University of North Texas, 2007. http://digital.library.unt.edu/permalink/meta-dc-3685.
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Cornelius, Ryan. "Meniscus." Thesis, University of North Texas, 2007. https://digital.library.unt.edu/ark:/67531/metadc3685/.
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Wataya, Celio Hitoshi. "Desenvolvimento de menisco de poli(álcool vinílico) (PVA) personalizado com auxílio da prototipagem rápida." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263546.
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Orientadores: Cecilia Amelia de Carvalho Zavaglia, Vanessa Petrilli BavarescoTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: O menisco como qualquer outro órgão, possui sua importância no funcionamento total do corpo humano. O tratamento para as lesões do menisco tem sido substituído pelo reparo, entretanto, conforme a gravidade da lesão torna-se inevitável a meniscectomia (cirurgia do menisco). Diante desta situação propôs-se desenvolver uma prótese que substitua o menisco lesionado, que possua suas características dimensionais, bem como suas propriedades mecânicas e tribológicas. A utilização da tecnologia da prototipagem rápida foi fundamental para se alcançar efetivamente o objetivo proposto. O material selecionado para a obtenção dessa prótese foi o poli(álcool vinílico) (PVA), por ser um polímero de baixo custo de produção, fácil obtenção e boas características para ser utilizado como um biomaterial. Os resultados dos ensaios mecânicos confirmaram a eficácia desse material. Valores como módulo de compressão 37,4 MPa (± 1,74), o módulo de fluência a indentação E = 3,6 MPa (±0,6); módulo de tensão e deformação, respectivamente iguais a 'SIGMA' = 3,2 MPa (±0,3) e ? = 148,4% (±39), evidenciam a possibilidade de utilização do PVA também como substituto do menisco humano. Outros ensaios também foram realizados como: ensaio in vitro e in vivo, tribológico e a Calorimetria Diferencial de Varredura (DSC), com resultados favoráveis a esse fim. Para a obtenção do menisco de PVA nas dimensões do menisco do paciente utilizou-se a tecnologia da prototipagem rápida (PR), primeiro para se obter o molde do menisco e depois então, o menisco por envasamento da solução de PVA no molde. Dois detalhes foram fundamentais para se chegar ao produto final, o primeiro foi o tratamento computacional dado à imagem de tomografia do joelho utilizando-se de programas livres como Invesalius e Rhinoceros e o segundo foi o uso do reticulante físico, o reagente orgânico dimetilsulfóxido (DMSO)
Abstract: The meniscus like any other organ, has its importance in the total functioning of the human body. The treatment for meniscal injuries has been replaced by the repair, however, according to the severity of the injury becomes inevitable meniscectomy (meniscus surgery). In this situation it was proposed to develop a prosthesis to replace the injured meniscus, which have their dimensional characteristics as well as their mechanical and tribological properties. The use of rapid prototyping technology was essential to effectively achieve the proposed objective. The material selected for obtaining a prosthesis is poly (vinyl alcohol) (PVA), being a polymer of low production cost, and easy to obtain good characteristics for use as a biomaterial. The results of mechanical tests have confirmed the effectiveness of this material. Values like compression module 37.4 MPa (± 1.74), the modulus of creep indentation E = 3,6 MPa (± 0.6), tensile modulus and strain, respectively equal to ' SIGMA' = 3.2 MPa (± 0.3) and ? = 148.4% (± 39) show the possibility of use of PVA as well as replacement of the meniscus human. Other tests were also conducted as in vitro and in vivo tribological and Differential Scanning Calorimetry (DSC), with results favorable to that end. To obtain the meniscus of PVA in the dimensions of the meniscus of the patient if the technology used rapid prototyping (RP), first to obtain the mold of the meniscus after then, the meniscus by filling the PVA solution in the mold. Two things were essential to reach the final product, the first treatment was given to computer tomography imaging of the knee using free programs like Rhinoceros and InVesalius and the second was the use of physical crosslinking, the organic reagent dimethyl sulfoxide (DMSO)
Doutorado
Materiais e Processos de Fabricação
Doutor em Engenharia Mecânica
10
Esposito, Andrea Rodrigues. "Crescimento de fibrocondrócitos sobre arcabouço de PLDLA/PCL-T para aplicação como prótese de menisco." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263902.
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Orientador: Eliana Aparecida de Rezende DuekDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: A engenharia tecidual utilizando células fibrocartilaginosas e arcabouços poliméricos representa uma alternativa para o tratamento de lesões do menisco. Neste estudo, arcabouços de PLDLA/PCL-T (90/10) contendo sacarose (50% m/v) foram obtidos por evaporação de solvente. Fibrocondrócitos provenientes do menisco de coelhos foram isolados e semeados diretamente sobre os arcabouços. Estudos in vitro demonstraram que o arcabouço não apresentou citotoxicidade e permitiu a adesão e o crescimento de fibrocondrócitos, bem como manutenção da síntese de matriz extracelular colágena nos tempos de 7, 14, 21 e 28 dias de cultivo. Os implantes de PLDLA/PCL-T foram realizados no menisco medial do joelho de 20 coelhos, após a meniscectomia total, obtendo-se três tratamentos: arcabouço com pré-cultivo celular por 21 dias, arcabouço sem células e controle. Após 12 e 24 semanas, as análises histológicas dos "neomeniscos" apresentaram a formação de fibrocartilagem nos implantes com os arcabouços. A presença de tecido fibrocartilaginoso maduro com fibras colágenas organizada foi predominantemente observada nos implantes realizados com os arcabouços pré-cultivados em comparação com os implantes sem células após 24 semanas. Este estudo demonstrou que a regeneração de uma importante estrutura fibrocartilaginosa pode ser alcançada utilizando arcabouço polimérico biorreabsorvível e células alógenas dentro dos princípios da engenharia de tecidos
Abstract: Tissue engineering of meniscus using fibrochondrocyte-like cells and bioreabsorbable polymer scaffolds could be an alternative option to treat meniscus injury. In this study PLDLA/PCL-T (90/10) scaffolds containing sucrose (50% m/v) were obtained by casting. Allogeneic meniscal cells were isolated from rabbit meniscus and directly seeded onto the scaffolds. In vitro studies showed that scaffolds did not present cytotoxicity and allowed fibrochondrocytes adhesion and ingrowth, as well as collagen extracellular matrix synthesis at 7, 14, 21 and 28 days of culture. The PLDLA/PCL-T implants were performed in the medial meniscus of 20 rabbit knee after total meniscectomy, obtained three treatments: pre-seeded 21 days scaffold, unseeded scaffold and control. Histology analysis of "neomenisci" sections at 12 and 24 weeks revealed the presence of fibrocartilage in the polymer implants. The presence of mature fibrocartilaginous tissue with organized collagen fibers was predominantly observed in the pre-cultured implants compared to unseeded implants after 24 weeks. This study demonstrates that regeneration of an important fibrocartilaginous structure can be achieved using a bioreabsorbable polymer scaffold and allogeneic cells-based tissue engineering approaches
Mestrado
Materiais e Processos de Fabricação
Mestre em Engenharia Mecânica
11
Cabrera, Andrea Rodrigues Espósito 1986. "Processamento, caracterização e desempenho in vivo de arcabouço biorreabsorvível de PLDLA-co-TMC." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265898.
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Orientador: Eliana Aparecida de Rezende DuekTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: Estruturas tridimensionais têm sido obtidas por diversas técnicas e representam um importante enfoque no desenvolvimento de suportes porosos para a engenharia tecidual. O objetivo deste trabalho foi desenvolver e caracterizar arcabouços tridimensionais porosos de poli(L-co-D,L ácido lático-co-trimetileno carbonato), PLDLA-co-TMC, obtidos pela técnica de deposição de fibras 3D. Arcabouços do terpolímero PLDLA-co-TMC, nas proporções 70:30 e 50:50, foram obtidos e caracterizados por microscopia eletrônica de varredura, cromatografia de permeação em gel, calorimetria exploratória diferencial, análise termogravimétrica, ensaio mecânico de compressão e estudo de degradação in vitro, os quais evidenciaram suas características amorfas, geometria cilíndrica e poros interconectados. O estudo de degradação in vitro, apresentou expressiva perda das propriedades mecânicas compatíveis com queda na massa molar, acompanhada de alterações na morfologia. Avaliou-se a histocompatibilidade da associação de células-tronco mesenquimais provenientes da medula óssea de coelhos e arcabouços de PLDLA-co-TMC (70:30), obtidos pelo método de evaporação de solvente com adição de sacarose (50%), na regeneração do menisco. Nove coelhos Nova Zelândia foram submetidos a meniscectomia medial total, obtendo-se três tratamentos: implante do arcabouço de PLDLA-co-TMC com pré-cultivo celular, implante de arcabouço de PLDLA-co-TMC puro (sem células) e controle negativo (defeito sem implante). Após 24 semanas, os resultados evidenciaram a presença de fibrocartilagem nos animais tratados com arcabouço polimérico. Contudo, a regeneração obtida com arcabouços de PLDLA-co-TMC pré-cultivados com células-tronco mesenquimais apresentou-se semelhante ao tecido fibrocartilaginoso maduro do menisco normal, tanto macroscopicamente quanto histologicamente. Este estudo demonstrou a eficácia do arcabouço de PLDLA-co-TMC (70:30) na regeneração fibrocartilaginosa e o potencial do pré-cultivo de células mesenquimais na engenharia tecidual, sem o uso de fatores de crescimento. Conclui-se que os polímeros biorreabsorvíveis representam uma alternativa promissora para a regeneração tecidual
Abstract: Three-dimensional structures have been obtained by various techniques and are an important focus in the development of porous scaffolds for tissue engineering. The aim of this study was to develop and characterize three-dimensional porous scaffolds of poly (L-co-D, L lactide-co-trimethylene carbonate), PLDLA-co-TMC, obtained by 3D fiber deposition technique. The PLDLA-co-TMC terpolymer scaffolds, 70:30 and 50:50, were obtained and characterized by scanning electron microscopy, gel permeation chromatography, differential scanning calorimetry, thermal gravimetric analysis, compression mechanical testing and study on in-vitro degradation, which exhibited its amorphous characteristics, cylindrical geometry and interconnected pores. The in-vitro degradation study showed significant loss of mechanical properties compatible with a decrease in molar mass, accompanied by changes in morphology. The histocompatibility association of mesenchymal stem cells from rabbits bone marrow, and PLDLA-co-TMC (70:30) scaffolds, obtained by casting with sucrose (50%), was evaluated in the meniscus regeneration, proving the potential of cell culture at in vivo tissue regeneration. Nine New Zealand rabbits underwent total medial meniscectomy, yielding three treatments: implantation of the seeded PLDLA-co-TMC scaffold, implantation of the unseeded PLDLA-co-TMC and negative control (defect without any implant). After 24 weeks, the results revealed the presence of fibrocartilage in the animals treated with polymer. However, the regeneration obtained with the seeded PLDLA-co-TMC scaffolds with mesenchymal stem cells had become intimal to mature fibrocartilaginous tissue of normal meniscus both macroscopically and histologically. This study demonstrated the effectiveness of the PLDLA-co-TMC (70:30) scaffold in meniscus regeneration and the potential of mesenchymal stem cells in tissue engineering, without the use of growth factors. It is concluded that bioresorbable polymers represent a promising alternative for tissue regeneration
Doutorado
Materiais e Processos de Fabricação
Doutora em Engenharia Mecânica
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Pospíchal, Oldřich. "Návrh kinematiky a řezné geometrie funkční části artroskopických kleští." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231468.
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This Thesis presents a design innovation in arthroscopic forceps. Based on surveying the subject-matter literature on arthroscopic surgery of the knee, design changes are proposed to alter the cutting geometry of the functional end of the instrument to improve its utility. The proposed changes are imple-mented in a prototype, which is then compared with the current design. The comparison is made by testing the functioning of the instrument and the force required to shear the test material.
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Marsano, Anna. "Engineering of human meniscus substitute /." [S.l.] : [s.n.], 2006. http://library.epfl.ch/theses/?nr=3439.
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MacKenzie, Kathleen S. (Kathleen Sheehan). "Meniscus movement in respiratory airways." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/39380.
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Zhang, Xiangkai. "Regional Comparisons of Porcine Menisci." 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/202805.
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Aldrin, Felicia. "Automated Segmentation of the Meniscus." Thesis, KTH, Fysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-211907.
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馬智申 and Chi-san Jason Ma. "The mobility of human knee menisci." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1995. http://hub.hku.hk/bib/B31212554.
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Mendoza, Valera Luis Alberto. "Menisco discoide: signos, síntomas e incidencia." Bachelor's thesis, Universidad Nacional Mayor de San Marcos, 2013. https://hdl.handle.net/20.500.12672/12714.
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Publicación a texto completo no autorizada por el autorDetermina los signos, síntomas e incidencia de Menisco Discoide en pacientes operados con artroscopía por Meniscopatía. Estudio Descriptivo, analítico, retrospectivo, en el cual se toma a todos los pacientes operados con artroscopía por meniscopatía desde junio del 2010 hasta diciembre del 2012, en el Hospital D. A. Carrión, utilizando las historias clínicas, reportes operatorios y la ficha de recolección de datos. Se analizaron 337 casos de artroscopias, obteniendo 23 con Menisco Discoide, incidencia de 6.82%. Obteniendo un predominio en mujeres a razón de 1.8/1. Se evidenció dolor en el 100% de los casos, Inestabilidad en 60.9%, crujido en el 56.5%, bloqueo articular en el 47.8%, McMurray y Apley en el 52.1% de casos y únicamente se encontró 01 caso de Menisco Discoide Medial con una incidencia de 0.3%. Se concluye que esta es una patología poco frecuente con una incidencia de 6.82%en nuestro estudio; con mayor predisposición en mujeres; y presentado un solo caso de Menisco Discoide medial. El dolor, inestabilidad y crujido son los signos y síntomas más frecuentes en la clínica del paciente, el resalto articular es un signo importante en Menisco Discoide no reportado.
Trabajo académico
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Ma, Chi-san Jason. "The mobility of human knee menisci /." [Hong Kong] : University of Hong Kong, 1995. http://sunzi.lib.hku.hk/hkuto/record.jsp?B14482927.
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Arcediano, Sánchez Miguel Ángel. "Utlidad de la altura de menisco lagrimal medido con tomografía de coherencia óptica en la evaluación del resultado de la cirugía de dacriocistorrinostomía externa." Doctoral thesis, Universitat Autònoma de Barcelona, 2016. http://hdl.handle.net/10803/371465.
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Objetivos
La evaluación del resultado de la cirugía de DCR externa es controvertida haciendo difícil la comparación de los resultados entre los diferentes estudios. El objetivo principal de esta tesis doctoral es determinar la capacidad de la tomografía de coherencia óptica en la medición de la altura del menisco lagrimal para la evaluación postoperatoria de la DCR. Analizaremos también la sensibilidad y especificidad de esta prueba diagnóstica en la evaluación del éxito anatómico y funcional de la DCR; la asociación de la altura del menisco lagrimal medida con OCT con otros parámetros clínicos como la epífora o el test de irrigación; y la utilidad de la medida como factor pronóstico de la cirugía.
Material y métodos
Estudio prospectivo descriptivo intervencional y comparativo antes-después con datos apareados en una muestra de 55 ojos de 52 pacientes con diagnóstico de obstrucción de la vía lagrimal baja completa descartándose otras causas de epífora. Se evalúan los cambios en altura del menisco lagrimal tras la cirugía de DCR externa, realizándose una medida basal antes de la cirugía, a la semana después de la misma y a los dos meses. La variable principal es la altura del menisco lagrimal mediante OCT (FDRT OCT). Como variables secundarias se han recogido la medida del menisco lagrimal en lámpara de hendidura (FDRT), la presencia de epífora y el resultado del test de irrigación.
Para el análisis de los datos se ha utilizado el test de los rangos signados, el test de la U de Mann Whitney-Wilcoxon, curvas ROC para el análisis de sensibilidad/especificidad, el coeficiente de correlación de Pearson, el test de Bland-Altman y regresión logística en forma de odds ratio.
Resultados
La mediana preoperatoria de la variable FDRT OCT es de 0.679 mm. Los valores postoperatorios a la semana y a los 2 meses son 0,471 mm (p=0,6160) y 0,452 mm (p=0,096) respectivamente.
La curva ROC para la valoración del éxito anatómico (irrigación positiva) muestra una AUC de 0,8864 con una sensibilidad y especificidad obtenidas del 84,62% y del 78,57%. Los valores predictivos positivo y negativos son del 55% y del 94,29% para cada caso. Para la valoración del éxito funcional (epifora negativa) la curva ROC presenta una AUC de 0,8963 con una sensibilidad y especificidad del 82,35% y del 84,21% y unos valores predictivos positivo y negativo del 70% y del 91,43% respectivamente.
La altura del menisco lagrimal con OCT ha mostrado diferencias significativas con las variables epífora (p=0,0024 y p<0,0001) e irrigación (p< 0,0001 y p<0,0001) a la semana y a los dos meses; así los pacientes con epífora e irrigación negativas presentaban valores claramente más elevados en la variable FDRT OCT.
En el análisis de regresión logística de la variable FDRT OCT a la semana se han obtenido un odds ratio (OR) de 10,789 y de 6,366 para la presencia de una irrigación negativa y epífora a los dos meses.
Conclusiones
El OCT puede evaluar de forma cuantitativa y no invasiva los cambios perioperatorios del menisco lagrimal en la cirugía de DCR. Presenta una elevada exactitud diagnóstica de casi el 90% para la evaluación del éxito anatómico y funcional de manera que valores bajos del menisco lagrimal (por debajo de 0,49 mm) nos permiten asegurar el éxito de la técnica en un 95% de los casos. La medición a la semana tiene valor pronóstico del éxito de la cirugía a los dos meses.
Como conclusión, el OCT debe ser incluido dentro de las herramientas de evaluación del resultado de la cirugía de DCR.Aims The evaluation of the results of external DCR remains controversial which makes difficult comparison among different studies. The main purpose of this doctoral thesis is to assess the ability of the OCT to measure the height of the lacrimal meniscus for the postoperative evaluation of the DCR surgery. The secondary purposes are to perform an analysis of sensibility and specificity of this diagnostic technique to assess the functional and anatomical success of the DCR procedure; to determine the association between this measurement and other parameters used to evaluate the patency of DCR surgery such as the presence of epiphora and the irrigation test; and to study the usefulness of the measurement of height of the lacrimal meniscus with OCT one week after surgery as a prognostic factor of final success of this surgery. Methods This is a prospective interventional descriptive study with paired data (before and after surgery). The sample size is 55 eyes from 52 patients with a diagnosis of complete acquired nasolacrimal obstruction having excluded other causes of epiphora. Changes in the height of the lacrimal meniscus after DCR surgery are examined and measurements before, the week after and two months after surgery are evaluated. The main variable is the height of the lacrimal meniscus with OCT (FDRT OCT). The secondary variables are the height of the lacrimal meniscus at the slit lamp (FDRT), the presence of epiphora and the result of the irrigation test. The data are summarised in terms of mean, median, standard deviation, first and third quartil and range for quantitative variables and bar charts for qualitative variables. The data were analyzed using the signed-rank test, the Mann Whitney-Wilcoxon test, ROC curves, the Pearson´s correlation coefficient, the Bland-Altman plot for agreement and logistic regression in terms of odds ratio. Results The preoperative median value of the variable FDRT OCT is 0,679 mm. Postoperative values at first week and two months are 0,471 (p=0,6160) and 0,452 (p= 0,096) respectively. ROC curve to evaluate the anatomic success (positive irrigation test) shows an AUC of 0,8864 with a sensitivity and specificity of 84,62% and 78,57%. Positive and negative predictive values are 55% and 94,29% . To assess the functional success (absence of epiphora) the AUC obtained is 0,8963 with a sensitivity and specificity of 82,35% and 84,21%; and the positive and negative predictive values are 70% and 91,43%. The tear meniscus height with OCT has shown significant differences with the value of the variables epiphora (p=0.0024 and p>0,0001) and irrigation (p<0,0001 and p<0,0001) at the first week and the second month after surgery; so patients with clinical epiphora and a negative irrigation test have significant higher values for the FDRT OCT variable. The logistic regression analysis for the FDRT OCT values at the first week showed an odds ratio of 10,789 for the presence of a negative irrigation test and 6,366 for the presence of epiphora at the two months. Conclusions OCT can evaluate noninvasively and quantitatively perioperative tear meniscus changes in external dacryocystorhinostomy. It has a diagnostic ability of 90% to assess anatomical and functional success in DCR surgery; considering our results we conclude that low values of tear meniscus (inferior to 0,49 mm) have a probability of success in 95% of cases. Measurements made at first week have a prognostic value as a marker of success of the surgical technique. As a conclusion, we recommend to include OCT as a diagnostic tool in assessing the result of DCR surgery.
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Yasura, Ko. "Estimation of the mechanical property of meniscus using ultrasound : examinations of native meniscus and effects of enzymatic digestion." Kyoto University, 2007. http://hdl.handle.net/2433/135773.
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Iversen, Fionn. "Meniscus Dynamics in Aluminium Extrusion Ingot Casting." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for materialteknologi, 2002. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-527.
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In the modern process of continuous Direct Chill (DC) hot top casting of aluminium extrusion ingot with gas slip, poor surface quality of the cast ingot can still be a problem. In the worst cases pronounced surface wrinkling may occur coupled with periodic zones of reduced grain size, macrosegregation and exudation at the surface. The observed surface irregularities are believed to be linked to periodic oscillations or folding of the free molten aluminium surface in the mould, the meniscus, resulting in varying solidification conditions. The focus of this work is to gain a better understanding of the dynamics of the meniscus and the effect it has on ingot surface formation.
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Rubins, Ian Michael. "Allotransplantation of frozen irradiated menisci in rabbits." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61219.
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The meniscus is essential for normal knee function. Previously considered unimportant, removal was performed when injured. This frequently led to degenerative arthritic changes. Today surgeons attempt to repair or minimally resect torn menisci, however many patients are encountered with irreparable tears or previously removed menisci. In these patients meniscale transplantation may prevent degenerative arthritis from developing.Problems facing transplantation are ability to store tissues and prevent disease transmission. To overcome this, freezing and irradiation effects were examined on 60 rabbits undergoing medial meniscal transplantation. Fresh, frozen, and frozen-irradiated allografts were followed up to 17 months, 10 other rabbits underwent meniscectomy alone.
Zero-time studies revealed that freezing with or without irradiation rendered cells non-viable with no changes in mechanical properties. At long term follow-up, all grafts healed, and showed repopulation with metabolically active cells determined radioautographically. Mechanical properties were unchanged, except for a decreased time constant in the frozen group. Degenerative changes were not significantly different among groups.
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Diogo, Lucia Maria Izique. "Elastografia Acoustic Radiation Force Impulse (ARFI) das estruturas do joelho canino /." Jaboticabal, 2018. http://hdl.handle.net/11449/153996.
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Orientador: Bruno Watanabe MintoResumo: O presente estudo objetiva estabelecer padrões elastográficos normais das principais estruturas da articulação femorotibiopatelar (joelho) de cães saudáveis, em diferentes faixas etárias. Foram examinados 30 cães (60 articulações) da raça Beagle sem alterações musculoesqueléticas, os quais foram distribuídos em três grupos: jovens, adultos e idosos. Realizou-se elastografia ARFI do ligamento patelar, menisco medial, ligamento cruzado caudal e ligamento cruzado cranial de cada articulação. Análises qualitativas e quantitativas detectaram correlação positiva da velocidade de cisalhamento, ou seja, da rigidez das estruturas, com a idade dos cães. O ligamento patelar apresentou aumento gradual de sua rigidez em relação à idade; já o menisco e os ligamentos cruzados mostraram-se mais rígidos nos filhotes do que nos adultos, mas também revelaram suas maiores rigidezes nos animais idosos. Avaliou-se também a diferença de elasticidade das estruturas de acordo com o gênero e a condição reprodutiva dos animais. As fêmeas apresentaram todas as estruturas mais rígidas que os machos, com velocidades de cisalhamento diferindo entre 0,30 e 0,36 m/s dentre os dois gêneros; e apenas o menisco medial não se mostrou mais rígido nos animais castrados em relação aos inteiros, sendo a diferença daquele de apenas 0,02 m/s e a dos ligamentos de 0,40 a 0,47 m/s entre os grupos. Já quanto ao peso, não houve significância estatística em relação à elasticidade das estruturas. Tais achados corroboram os ... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The aim of this study is to establish normal elastographic patterns of the main knee structures of healthy dogs in different age groups. Thirty Beagles (60 joints) without musculoskeletal diseases were divided into three groups: young, adult and elderly. We performed ARFI elastography of the patellar ligament, medial meniscus, caudal cruciate ligament and cranial cruciate ligament. Qualitative and quantitative analyzes were performed, detecting a positive correlation of the shear velocity (rigidity of the structures) and the age of the dogs (p = 0.012). The patellar ligament showed a gradual increase in its rigidity in relation to age; the meniscus and the cruciate ligaments were more rigid in the pups than in adults, but also showed greater rigidity in elderly animals. The difference in elasticity of structures according to sex and reproductive condition was also evaluated. The females had all the structures more rigid than the males, with shear velocities differing between 0.30 and 0.36 m / s between the two groups. Only the medial meniscus did not appear to be more rigid in castrated animals. There was no statistical significance regarding the elasticity of the structures, according to weight. ARFI elastography is feasible technique in canine knees, not only as a method for the early diagnosis of ligament and meniscal alterations, but also to evaluate repercussion of instability in the contralateral limb and the impact of surgical and physiotherapeutic treatments. It is be... (Complete abstract click electronic access below)
Mestre
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Luther, Jill K. Cook James L. "Comprehensive characterization of canine meniscal pathology." Diss., Columbia, Mo. : University of Missouri-Columbia, 2010. http://hdl.handle.net/10355/.
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The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on July 13, 2010). Thesis advisor: James L. Cook "May 2010" Includes bibliographical references.
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Bitar, Alexandre Carneiro. "Estudo comparativo das alterações degenerativas dos meniscos medial e lateral na artrose do joelho em varo." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/5/5140/tde-15102014-164833/.
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Na prática clínica, a queixa de dor no joelho em pacientes, a partir da quinta década de vida, é muito freqüente e comumente atribuída à lesão meniscal degenerativa. A relação entre a lesão degenerativa do menisco e a artrose é controversa, assim como a relação do varo e a evolução para artrose do joelho. Foram estudadas as alterações macroscópicas e microscópicas dos meniscos em 21 pacientes com deformidade em varo submetidos a artroplastia total do joelho, decorrente de artrose do joelho. Analisou-se, também, a relação destas lesões com o grau de artrose e varismo dos pacientes. Foram encontrados 9 de 21 meniscos com lesões, sendo o menisco mais acometido o medial e a lesão mais freqüente em clivagem horizontal. Neste modelo clínico de artrose com joelho em varo, afirma-se que: 1) Não foi possível estabelecer correlação entre o grau de artrose e a maior ocorrência de lesões meniscais macroscópicas; 2) Não se observou relação entre a maior gravidade da deformidade angular em varo dos joelhos com o aumento da ocorrência de lesões meniscais; 3) Quando ocorreram, as lesões meniscais preponderaram no menisco medial e as mais freqüentes foram as em clivagem horizontal; 4) Os meniscos apresentaram alterações microscópicas significativas resultantes do processo de artrose dos joelhos; no entanto, não há evidência que a presença de lesões é estatisticamente diferente entre os meniscos lateral e medialIn clinical practice, the knee pain complaint by patients from the fifth life decade is very frequent and commonly assigned to degenerative meniscal injury. The relationship between degenerative meniscal injury and arthrosis is controversial, as well as the relationship between genu varum and evolution to knee arthrosis. Macroscopic and microscopic meniscal changes in 21 patients with varum deformities undergoing total knee arthroplasty secondary to knee arthrosis were also studied. The relationship between these injuries and the degree of arthrosis and varism of patients were also studied. Of 21 menisci, 9 were found to have injuries, the most affected being the medial meniscus and the most frequent was the horizontal cleavage meniscal injury. In this clinical model of arthrosis with varum knee (1) it was not possible to establish any correlation between the degree of arthrosis and the higher occurrence of macroscopic meniscal injuries; (2) no relationship was observed between higher severity of genu varum angular deformity and increase of meniscal injury occurrence; (3) meniscal injuries prevailed in the medial meniscus, horizontal cleavage meniscal injuries being the most frequent; (4) the menisci presented significant microscopic changes resulting from the knee arthrosis process; however, no evidence was found that the presence of injuries is statistically different between lateral and medial menisci
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Groot, Jacqueline Hermina de. "Porous polymeric elastomers for repair and replacement of the knee joint meniscus." [S.l. : [Groningen] : s.n.] ; [University Library Groningen] [Host], 1995. http://irs.ub.rug.nl/ppn/141124342.
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Halili, Ndreu Albana. "Collagen-based Meniscus Tissue Engineering: Design And Application." Phd thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613451/index.pdf.
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Meniscus is a wedge shaped structure, with a convex base attached to a flat tibial surface, and with a concave femoral surface, on which femur and tibia articulate. It has several functions including joint lubrication, shock absorption, load transmission and joint stability. Various methods were tried to treat meniscal tears but each has its own drawbacks. Tissue engineering seems to be a promising solution that avoids all the problems associated with the other approaches. In this study, a three dimensional (3D) collagen-based structure was prepared by tissue engineering to mimic the natural human meniscus. Three different foams prepared under different conditions were combined and nano/microfibrous layers were placed in between them. To mimic the properties of the natural tissue, the top layer was composed of collagen-chondroitin sulfate-hyaluronic acid (Coll-CS-HA) prepared by freezing at -20ºC followed by lyophilization. The middle and bottom layers were made with just collagen after freezing at -20º
C and -80º
C, respectively and lyophilization. Aligned nano/microfibers were prepared using collagen-poly(L-lactic-co-glycolic acid (Coll-PLGA). Various crosslinking procedures such as 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS), genipin (GP), glutaraldehyde (GLU) either alone or in combination with dehydrothermal treatment (DHT) were used and based on both compressive and tensile properties, the best crosslinker was chosen to be DHT+EDC/NHS. Mechanical properties (compressive, tensile and shear) of the dry foams and the final 3D construct were evaluated. The highest mechanical properties were obtained with the 3D construct. Then all these foams and the 3D construct were seeded with human fibrochondrocytes to study the cell behavior such as attachment, proliferation, and extracellular matrix (ECM) and glucosaminoglycan (GAG) production. Furthermore, the influence of cell seeding on the compressive properties of wet individual foams and the 3D construct was observed. As expected, the highest cell proliferation and compressive properties were obtained with the 3D construct. Finally, the 3D constructs, seeded with fibrochondrocytes, were implanted in New Zealand rabbits after meniscectomy. The initial microscopical examination show that the 3D construct has a significant potential as a meniscus substitute.
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Brown, Gregory Alexander. "Load-bearing role of the human knee meniscus." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/29204.
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Thesis (Ph. D.)--Harvard University--Massachusetts Institute of Technology Division of Health Sciences and Technology, Program in Medical Engineering and Medical Physics, 1990.Includes bibliographical references (leaves 185-203).
by Gregory Alexander Brown.
Ph.D.
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Johansson, Isabell, and Lisa Ivarsson. "Textilteknisk menisk." Thesis, Högskolan i Borås, Institutionen Textilhögskolan, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-16396.
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Denna rapport presenterar det examensarbete som gjorts i samarbete med företaget Artimplant. Syftet med arbetet är att ta fram en prototyp av ett meniskimplantat i trikåteknik. Det kräver stickning av en given form och att prototypen ska inneha vissa egenskaper.Ämnesområden som berörs under arbetets gång är textiltillverkning med inriktning mot väfttrikå samt medicinsk textil. Förutom textila ämnesområden tas även ämnen som knäledens anatomi och meniskens uppbyggnad, funktion och skador upp. Kunskaper inom dessa områden krävs för att på bästa sätt ta fram prototyper av meniskimplantat.Att sticka det triangulära tvärsnittet och den böjda formen som krävs för ett meniskimplantat har varit ett arbete som pågått under hela projektet. För att åstadkomma detta och erhålla egenskaper som krävs för en prototyp av ett meniskimplantat har diskussioner förts med produktutvecklare och tekniker, både på Artimplant och på Textilhögskolan för att diskutera möjligheter och utformning. Även möte med ortoped och en av initiativtagarna till Artimplant har givit värdefull information kring hur en prototyp till ett meniskimplantat bör utformas. Dessutom diskuteras och analyseras frågor kring industrialisering av processen och framtagning av kravspecifikation samt hur prototyper förhåller sig till den framtagna kravspecifikationen.Varje enskild prototyp granskas efter framtagning och utvalda prototyper genomgår tester där resultaten jämförs mellan dessa samt enligt kravspecifikation. Detta tillvägagångssätt möjliggör ständiga förbättringar för varje prototyp som tas fram.En slutlig prototyp av ett meniskimplantat har tagits fram och dess egenskaper och utformning möter den framtagna kravspecifikationen. Dess grepp och känsla är liknande en naturlig menisk då den är töj- och formbar, elastisk samt har en slät yta. Formbarheten på prototypen möjliggör anpassning av storlek och positionering vilket medför bra integration till ledytorna. Ytterligare likheter som prototypen har med en naturlig menisk är dess förmåga att stå emot deformation vid kompression.This report presents the thesis that was executed at the company Artimplant. The purpose of this work is to produce a prototype of a meniscus implant in knitted technology. It demands knitting a specific shape and that the prototype shall possess certain properties.The subjects that the report covers are textile manufacturing with focus on weft knits and medical textile. Besides subjects concerning textile technology there are also subjects as the anatomy of knee joint and the meniscus structure, function and damage. Knowledge in these areas is required to develop a prototype of a meniscus implant in the best way as possible.Knitting the triangular cross section and getting the curved shape that a meniscus implant requires have been under constant development during the project. To achieve this design and to obtain required properties for a prototype of a meniscus implant have discussion been held with product developer and technicians, both at Artimplant and at the Swedish School of Textile, to discuss the opportunities and design. Meetings with an orthopaedic, who also was one of the initiators of Artimplant, have provided valuable information regarding the design of a prototype of a meniscus implant. Furthermore, issues related to industrialization of the process, composing a requirement specification and how prototypes are related to the requirement specification are discussed and analyzed.Each produced prototype is analyzed and thereafter prototypes are selected for further tests. The results from the tests are compared between the selected prototypes and according to the requirement specification. This line of action allows continuous improvement for each produced prototype.A final prototype of a meniscus implant has been developed and its properties and design fulfil all of the criteria in the requirement specification. Its hand is similar to a natural meniscus because of its stretchability, elasticity, flexibility and the surface smoothness. The flexibility of the prototype allows adjustments of size and positioning which results in good integration to the knee-joint. Further resemblance is the prototype’s ability to resist deformation during compression.Program: Textilingenjörsutbildningen
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Bahcecioglu, Gokhan. "Poly(l-lactic Acid) (plla)-based Meniscus Tissue Engineering." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613968/index.pdf.
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Meniscus is a fibrocartilaginous tissue which plays an important role in joint stability, lubrication, and load bearing and transmission. Meniscal tears are commonly encountered in sports activities, or caused by degeneration of the cartilage with ageing. They lead to pain, loss of work, disturbed biomechanics of the knee and inability to walk or even move the legs. As the meniscal tissue is avascular in the inner portion, injury to this part does not heal by itself, and therefore treatments are needed. In some cases when complex tears occur, the tissue cannot be successfully treated with the conventional methods.
Tissue engineering appears to be a promising alternative to treat such complex tears. It includes the application of cells on scaffolds (or cell carriers), and provision of bioactive agents to the site of injury in order to regenerate the damaged tissue. The cells and the bioactive agents are involved in the synthesis of the new tissue, while the scaffold acts as a support to guide the cells until the new tissue is formed, and it is slowly absorbed by the body leaving the new tissue behind. Thus, a natural tissue is generated at the end. Few studies have been reported on the tissue engineering of meniscus, but neither of them was able to completely mimic the meniscus structure, nor could they succeed in constructing scaffolds with sufficiently high tensile properties.
In the current in vitro study, a novel 3D construct was proposed, in which the natural tissue is perfectly mimicked. The 3D construct consisted of aligned collagen fibers embedded within a foam network which stabilizes the structure. The foam was prepared by freezing a polymer solution with a certain concentration, and lyophilizing it. Aligned fibers were aimed to improve the tensile properties. The construct was impregnated in alginate gel, which was then crosslinked, to improve the compressive properties.
The foam was prepared from (poly(L-lactic acid)/poly(lactic-co-glycolic acid) (PLLA/PLGA) solutions of various concentrations (2%, 2.5%, 3%, and 4% w/v) and at different freezing temperatures (-20oC or -80oC) to select the best preparation condition. After analysis of the microstructure and mechanical properties, foams prepared from 3% polymer solution frozen at -20oC were found to be the most appropriate for use as scaffold for the 3D construct, since they had large pores, high and interconnected porosity, as well as high mechanical strength.
The 3D constructs were seeded with human meniscus cells and incubated for 21 days. Cell behavior on the constructs was examined. Cell attachment and proliferation was found to be better with the constructs not coated with alginate. However, the constructs coated with alginate demonstrated higher compressive strength. It was also found that incorporation of collagen fibers significantly improved the tensile properties.
All the constructs were shown to lead to the production of extracellular components specific for fibrocartilages, and thus it was concluded that they were promising for use in meniscal replacement.
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Bandlitz, Stefan. "The role of the meniscus in the tear film." Thesis, Cardiff University, 2015. http://orca.cf.ac.uk/73390/.
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In the diagnosis of dry eye, an evaluation of tear fluid volume is an important parameter. The tear menisci hold approximately 75-90% of the overall tear fluid volume and serve as reservoirs, supplying tears to the pre-corneal tear film. The measurement of the anterior curvature radius of the tear meniscus (TMR) is an indicator of tear film volume and when it is performed non-invasively has been found to have good dry eye diagnostic accuracies. Optical coherence tomography and meniscometry are existing techniques that can measure TMR non-invasively. These techniques have not found wide application among clinicians, either because they are not commercially available or they are too expensive. This PhD describes a series of experiments that investigated the development, evaluation and application of a new instrument for non-invasive tear meniscus measurement. From the results of these studies, it can be concluded: A Portable Digital Meniscometer (PDM) was developed. This consists of an application tool for the iPod-touch, a slit-lamp holder for the iPod-touch and an image analysis software for TMR calculation. A simple iPod-touch or an iPhone mounted on a commercially available digital slit-lamp can be used to project a grid of black and white lines on the tear meniscus. Using the principal of reflective meniscometry, the radius of the lower tear meniscus can be non-invasively measured. This newly developed instrument is a simple, mobile and useful device for measuring tear meniscus radius, and therefore tear volume, and is suitable for use by clinicians. The newly developed PDM was evaluated in vitro and in vivo. It produced accurate and reliable measurements and provided similar values for the tear meniscus radius, in human studies, to the existing video-meniscometer. PDM and OCT measurements of the TMR were significantly correlated. Since with the PDM no image calibration is needed, it seems to be a quick and non-invasive technique for evaluation of tear fluid quantity. The PDM appears to measure the radius of the central section of the tear meniscus The PDM was able to non-invasively measure alterations in TMR and TMH along the lower lid. The flatter TMR and higher TMH at the nasal and temporal locations may be caused by the LIPCOF degree of the underlying conjunctiva. To avoid any interference by LIPCOF, it is recommended that TMR and TMH be measured along the lower lid margin below the pupil centre. Furthermore, the PDM was able to usefully detect changes in TMR following the instillation of artificial tears. The difference in residence time is likely to reflect the different viscosity and Newtonian properties of these drops. An overload with a large drop may result in initial increased blink rate. Blink rate at baseline is significantly related to dry eye symptoms.
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Hasan, Jahid. "Decellularisation and characterisation of porcine bone-medial meniscus-bone." Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/7661/.
Full textAbstract:
The meniscus in the knee functions to absorb shock and transmit load within the joint. Problems arise when the meniscus is injured or damaged as the meniscus’ healing potential is limited by the limited vascular supply extending only ~20% of the way through the mature meniscus. Current treatment options are only effective at abating further degeneration and osteoarthritis due to altered joint mechanics. Replacement of the meniscus has the potential to prevent the onset of osteoarthritis by restoring native joint mechanics. Here we aim to develop a decellularisation protocol for porcine medial meniscus with added bone blocks for easy fixation for use as a meniscal replacement. Menisci were decellularised using a low sodium dodecyl sulphate (SDS) method including freeze-thaw cycles, hypertonic, hypotonic and nuclease wash steps, as well as mechanical removal of cellular material. Decellularised menisci were then characterised histologically, immunohistochemically, biochemically and biomechanically for successful decellularisation and compared to native meniscus. Histology revealed the absence of whole cells and nuclei from meniscus and bone, while quantification of DNA revealed ~96% and ~91% removal of DNA from meniscus and bone, respectively. Immunohistochemical analysis showed retention of major structural collagens I, II and II; however there was complete removal of collagen IV and some loss of collagen VI. Hydroxyproline assay showed retention of collagen and the collagen content of native meniscus was 802.90 (± 52.95, 95% CL) mg.g-1 dry weight and for decellularised meniscus was 935.35 (± 18.03, 95% CL) mg.g-1 dry weight, however there was a complete loss of GAGs from the decellularised matrices as revealed by Safranin O staining and quantified using dimethyl methylene blue assay (23.49 ± 8.63 μg.mg-1 vs. 0.30 ± 0.47 μg.mg-1, 95% C.I.). There was also a 51% reduction in calcium content of the decellularised bone blocks when compared to native bone blocks. Material properties of meniscus were obtained using uniaxial tensile and indentation testing with no significant differences observed between native and decellularised groups under tension although greater deformation was seen for decellularised samples under compression. Unconfined compression of bone however revealed a significant decrease in the compressive modulus and strength of decellularised bone blocks. Differential scanning calorimetry revealed no significant differences in thermal stability between native and decellularised meniscus except for in the attachment region where collagen was mechanically manipulated prior to decellularisation. Magnetic resonance imaging (MRI) also revealed no gross differences between native and decellularised bone and meniscus. Extract and contact cytotoxicity assays were used to determine biocompatibility of decellularised bone-meniscus-bone and residual SDS content determined using radio-labelled 14C SDS. There was 0.289 μg.mg-1 of residual SDS in decellularised bone-meniscus-bone and assays showed no cytotoxicity to 3T3 and BHK cells. The immunogenic galactose-α-1,3-galactose epitope could not be detected in decellularised meniscus by immunohistochemistry. In conclusion, a protocol for the successful decellularisation of porcine bone-medial meniscus-bone has been developed which retains the structure and tensile properties of native meniscus and is non-cytotoxic. Further investigation is required to determine whether loss of mechanical strength in the bone will prevent effective fixation in vivo.
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Yang, Xin. "Chondrogenesis enhancement of meniscus derived fibrochondrocytes bei dynamic hydrostatic pressure /." Regensburg, 2007. http://opac.nebis.ch/cgi-bin/showAbstract.pl?sys=000253214.
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Wilkins, Robert Douglas. "Tensile properties of fibrocartilage from the human knee joint meniscus." Thesis, The University of Sydney, 1990. https://hdl.handle.net/2123/26303.
Full textAbstract:
The mechanical function of the human knee joint meniscus is not yet well understood. While the tissue has previously been regarded as superfluous. recent research suggests that it may perform an important mechanical role in the healthy joint, and should be preserved or repaired where possible.
In an effort to contribute to the understanding of this tissue, tensile tests have been performed on small specimens from the meniscus under a range of conditions to provide more information on the tissue function.
The use of uni-axial tensile tests is based on the concept of the meniscus as a compressed tissue developing circumferential tension in its outer region to withstand the applied loading of a normal physiological joint. Circumferentially aligned collagen fibres withstand this tension and retain the meniscis in the joint cavity. where its assumed primary function is to increase the weight bearing interface, thereby reducing joint stresses.
New methods and apparatus have been developed for the tensile testing of micro specimens from the meniscus under a range of controlled conditions. While many of the imposed testing conditions are remote from normal physiological conditions, they have been carefully chosen to elucidate information concerning the contribution of various tissue components to the observed mechanical function of the tissue.
New data are presented concerning the tissue response to cyclic extension, stress relaxation, refrigerated and frozen storage, chemically induced water uptake, chemical fixation, and hyaluronidase digestion. These results are discussed and interpreted in relation to the mechanical function of the meniscus in the normal weight bearing knee joint.
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Popelka, Michal. "Studium přechodových jevů mezi zcela zaplaveným a hladovějícím elastohydrodynamicky mazaným kontaktem." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230142.
Full textAbstract:
The diploma thesis deals with The study of transition between fully flooded and starved regimes in EHL Contact. The work is focused on problems of starved contact and surface texturing of rubbing surfaces. Surface texturing of rubbing surfaces is one of the adjustments that cause in a sense improved lubricity and reduce friction and wear. The aim of this study is to compare numerical models with real experimental results measured on the Experimental apparatus.
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Smith, Nicholas A. "An investigation into meniscal allograft transplantation for the treatment of the symptomatic meniscal deficient knee." Thesis, University of Warwick, 2015. http://wrap.warwick.ac.uk/79960/.
Full textAbstract:
Meniscectomy is a common treatment for a young patient with a traumatic meniscal tear, despite the known negative consequences. Meniscal allograft transplantation has been performed for over thirty years in young symptomatic patients following a meniscectomy but it has never been rigorously evaluated for effectiveness. Therefore the aim of this thesis was to perform the development and pilot work to inform a future multi-centre pragmatic randomised controlled trial comparing meniscal allograft transplantation to physiotherapy. Systematic reviews in this thesis showed that in case series, meniscal allograft transplantation resulted in improved patient reported outcome measures in the short and medium term, although there were no comparator groups. There was no strong evidence for chondroprotection with either meniscal allograft transplantation or physiotherapy in this patient population. In the systematic review it was also identified that full thickness cartilage lesions were a contraindication to meniscal allograft transplantation for most surgeons. A Cox proportional hazards model was used on a case series of meniscal allograft transplantations performed locally, which showed that a full thickness cartilage lesion was a strong predictor of failure. It was therefore determined that these patients should be excluded from the pilot trial. A comprehensive cohort study incorporating a pilot randomised controlled trial was performed, with 36 participants being recruited over one year. The trial processes worked successfully and the pilot randomised trial recruitment rate was 55%. There were no losses to follow up in the randomised arm of the trial. Patient reported outcome measures showed a trend towards a bigger improvement in the meniscal allograft transplantation group, which was statistically significant in the KOOS score when the randomised and preference groups were merged. Sample size calculations for the data in the trial using the KOOS score suggest that between 70 and 114 participants would be needed in a full trial. The results of this thesis suggest that a full trial is warranted and could be deliverable within the UK, with some small adjustments to the trial design.
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Mazzotti, Giulia. "Scaffold biomimetici per la riparazione di lesioni del menisco del ginocchio." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
Find full textAbstract:
Oltre 1,5 milioni di persone negli Stati Uniti e in Europa subiscono ogni anno un intervento chirurgico al menisco. Il menisco riveste un ruolo fondamentale nell’articolazione del ginocchio offrendo stabilità e sostegno. Agisce da ammortizzatore favorendo una distribuzione uniforme delle forze, inoltre lubrifica l’articolazione. Nella chirurgia ortopedica, le lesioni meniscali del ginocchio sono tra le più frequenti e se non vengono trattate adeguatamente e in tempi brevi, possono portare all’insorgenza di artrosi. Ad oggi, il trattamento delle lesioni meniscali è più orientato a metodi conservativi e all’approccio chirurgico comunemente noto come meniscectomia, cioè la rimozione totale o parziale della porzione di menisco lesionata. Tuttavia, questo metodo induce cambiamenti nelle condizioni di carico dell’articolazione del ginocchio, fino a causare il restringimento dello spazio articolare e la degenerazione della cartilagine. In questi casi, considerati i pro e i contro, si può valutare un trapianto anche se è scarsa la disponibilità di donatori. Negli ultimi anni, grazie allo sviluppo dell’ingegneria dei tessuti biologici, si sono sviluppati supporti porosi chiamati scaffold, in grado di promuovere l’accrescimento e il differenziamento cellulare, e di rispondere a caratteristiche meccaniche del tessuto che si vuole rigenerare.
L’obiettivo di questo elaborato è quello di approfondire le strategie di scaffolding più recenti per la rigenerazione del tessuto meniscale, analizzando quindi i biomateriali più utilizzati, le fonti cellulari e i fattori di crescita impiegati per la proliferazione delle cellule all’interno dello scaffold col fine di creare nuovo tessuto meniscale. Vengono inoltre presentati alcuni esempi di applicazioni in vivo e in vitro di studi recenti.
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Moran, Robert Stephen. "The mechanical properties and behavioural characteristics of human knee joint meniscus." Thesis, University of Edinburgh, 2001. http://hdl.handle.net/1842/12682.
Full textAbstract:
Considerable evidence indicates that damage, to or removal of, the menisci can have detrimental effects upon primary knee joint function and cause degeneration by predisposing the knee to the effects of osteoarticular disease. To understand fully how the menisci function, their intrinsic material properties and essential features of their behavioural response to loading conditions and how these properties vary throughout the tissue must be precisely defined. This provides the ability to understand the normal function of the knee meniscus, quantify pathologies, detect injurious mechanisms and evaluate the effects of injury and repair. Load-deformation studies, obtained through precisely prepared material samples and standardised loading conditions were used to obtain the relationship between stress and strain of the meniscus when subject to uniaxial compressive, tensile and shear loading in different orthogonal planes and regions. The fundamental understanding of the relationships between the structural organisation and biomechanical properties of fresh, human meniscal tissue has been reported. Failure mechanisms within the highly anisotropic and inhomogeneous material are presented. Material coefficients and mathematical equations modelling stress-strain response are defined and the effects of pathology, location and age effects have been determined. This primary information provides us with a better understanding of the functional behaviour of the meniscus under physiological loading conditions and an insight into possible failure mechanisms. The precise materials and mechanical property data presented will enable accurate computer simulations to be constructed and provide a reference by which future developments in the fields of meniscal repair and tissue engineering can be realistically assessed for performance in vivo.
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Galvan, Pareja Rodolfo Carlo. "Alta resolución diagnóstica de la sonografía para determinar desinserción del menisco." Bachelor's thesis, Universidad Nacional Mayor de San Marcos, 2007. https://hdl.handle.net/20.500.12672/14713.
Full textAbstract:
Se evaluó la capacidad de la sonografía en tiempo real para reconocer
las lesiones de menisco. Se estudiaron por sonografía 124 rodillas en 62 pacientes con
sospecha de lesión de menisco, correlacionandose los hallazgos con el examen
clínico, la artrografía y la artroscopia.
El estudio se llevó a cabo en el Departamento de Radiología y Ortopedia del Hospital
Clementito Fraga Filho, entre los años 1995 y 2002. De los 50 diagnósticos
confirmados de lesión del menisco, 36 presentaron alteraciones sonográficas. La
desinserción del menisco se confirmó con cirugía en 24 pacientes, siendo bien
visualizadas y reconocidas las alteraciones por sonografía en 22 de ellos, en tanto que
se les identificó artrográficamente solo en 14 casos.
Se encontraron algunos signos sonográficos muy específicos en el menisco con
desinserción como área hipoecogénica en la base y fragmentación en 83.3% de los
casos dando certeza en el diagnóstico de lesión en un porcentaje alto. Se concluye que
la evaluación sonográfica es útil y debe ser considerada como método diagnóstico en
los casos de sospecha de lesión del menisco.Trabajo académico
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Baker, Paul. "Occupational risk factors for meniscal injury." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393511.
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Steiger, Martyn R. "Gelatin-based bioadhesives for meniscal repair." Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/131882/1/Martyn_Steiger_Thesis.pdf.
Full textAbstract:
This research was motivated by the paucity of bioadhesives possessing suitable mechanical and biological properties for meniscal repair. Gelatin-based biomaterials cured with light were investigated for this application with a focus on their tensile properties when adhered to meniscal tissue. A novel methodology for tensile testing meniscal bioadhesive tensile properties was developed and employed successfully. Candidate gelatin-based bioadhesives were identified that demonstrated suitable tensile properties and cytocompatibility for meniscal tear applications.
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Paiva, Vanessa Carla [UNIFESP]. "A Correlação entre diferentes temperaturas e períodos de preservação sobre as fibras colágenas de meniscos de coelhos." Universidade Federal de São Paulo (UNIFESP), 2006. http://repositorio.unifesp.br/handle/11600/39219.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Objetivo: Quantificar as fibras colágenas de meniscos de coelhos submetidos à temperaturas e períodos de preservação variáveis. Métodos: Retirou-se assepticamente 120 meniscos (mediais e laterais) de 30 coelhos (Nova Zelândia), machos, idade entre 6/8 meses, peso médio de 3250g. Os meniscos foram congelados, de dois até trinta dias, a 7,2°Celsius negativos (n=60) e 73°Celsius negativos (n=60). A cada dois dias, de cada temperatura, foram descongelados quatro meniscos que foram encaminhados para o estudo histológico. A descrição morfológica foi feita com os cortes corados por HE, e para o estudo morfométrico os cortes foram corados pelo método de Picrosirius e posteriormente submetidos à polarização. A quntificação de área ocupada pelas fibras colágenas em cada lâmina foi calculada por subtração de imagens à partir do programa de software Image Pro Plus. Resultados: Na análise descritiva das médias percentuais de colágeno foram observadas diferenças maiores e estatisticamente significantes (p<0,001) à temperatura de 73ºCelsius negativos. A análise comparativa das médias percentuais de fibras colágenas ao longo dos períodos de preservação, embora com diferença de valores, apresentaram uma curva simétrica de variação. Também obervou-se que à partir do 14ºdia, em ambas temperaturas, a variação na porcentagem de fibras colágenas em relação aos demais períodos, não apresenta significância estatística, contudo a temperatura de 73ºCelsius negativos mostrou-se superior à 7,2ºCelsius negativos na preservação de fibras colágenas. A análise de regressão polinomial mostrou que a variação das médias percentuais de fibras colágenas é um polinômio de terceiro grau, sugerindo outras variáveis implicadas na preservação do colágeno. Conclusão: A temperatura de 73ºCelsius negativos mostrou médias percentuais de colágeno superiores em todos os períodos observados, porém à partir do 14º até o 30º dia de congelamento, a quantidade de fibras colágenas permanece estável em ambas temperaturas.
Objective: to quantify meniscuses’collagenous fibers of rabbits submitted to variable temperatures and conservation periods. Methods: One hundred and twenty (120) meniscuses (medial and lateral) were aseptically removed from 30 male rabbits (New Zealand), with age between 6/8 months and mean weight of 3,250g. The meniscuses were frozen between 2 and 30 days at 7,2o Celsius negative (n=60) and 73o Celsius negative (n=60). From each temperature group, four meniscuses were unfrozen every two days, which were sent to histological study. The morphological description was done with cuts colored with HE, and for the morphometric study the cuts were colored by the Picrosirius method and afterwards submitted to polarization. On each slide, the quantification of the area occupied by the collagenous fibers was calculated by image subtraction, using the Image Pro Plus software. Results: In the descriptive analysis of the collagenous’ mean percentages, greater and statistically significant differences (p<0.001) were observed at a temperature of 73o Celsius negative. The comparative analysis of the collagenous’ fibers mean percentages during the conservation periods, although with differences in values, presented a symmetric curve of variation. It was also observed that as from day 14th, in both temperatures, the variation on the collagenous fibers percentage in relation to the other periods, did not present statistical significance, although at the temperature of 73o Celsius negative showed to be superior to the 7,2o Celsius negative in preserving the collagenous fibers. The polynomial regression analysis showed that the variation of the mean percentages of collagenous fibers is a polynomial of third degree, suggesting other variables involved on the collagenous conservation. Conclusion: The temperature of 73o Celsius negative showed superior collagenous’ mean percentages in all observed periods, although as from the 14th up to the 30th days of freezing, the amount of collagenous fibers remained stable in both temperatures.
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Fourgeaud, Laura. "Analyse de la dynamique du film liquide dans un caloduc oscillant." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAY038/document.
Full textAbstract:
Nous étudions expérimentalement le comportement d'un film liquide, dit de Landau-Levich, lorsqu'il s'évapore dans une atmosphère constituée uniquement de sa vapeur.La dynamique de ce type de film est un paramètre-clef qui gouverne le fonctionnement des caloducs oscillant (en anglais PHP - Pulsating Heat Pipes). Les PHP sont des liens thermiques de forte conductance. Les recherches récentes leur attribuent un pouvoir de refroidissement très élevé, ce qui les rend particulièrement convoités par l'industrie. Leur géométrie est simple : il s'agit d'un tube capillaire enroulé en plusieurs branches entre une partie froide (condenseur) et une partie chaude (évaporateur). Le tube est rempli d'un fluide pur diphasique, c'est-à-dire présent sous la forme d'une succession de bulles de vapeur et de bouchons de liquide. Lorsque la différence de température entre l’évaporateur et le condenseur dépasse un certain seuil, les bulles et bouchons commencent à osciller dans le tube, entre les deux parties, ce qui permet au PHP de transférer la chaleur.Notre installation expérimentale représente un PHP dans sa configuration la plus simple, à branche unique. Une interface liquide-vapeur oscille dans un tube de section rectangulaire, et dépose un film liquide à chaque passage. Nous nous intéressons au mécanisme qui permet l'entretien de l'oscillation de l'interface, et fixe sa fréquence. L'équation de mouvement obtenue prend en compte la dissipation visqueuse engendrée par un écoulement oscillant. Dans les modèles actuels de PHP, l'hypothèse d'un écoulement de type Poiseuille est formulée. Or, notre approche montre que l'hypothèse d'un écoulement faiblement inertiel est mieux adaptée, conduit à une dissipation deux fois supérieure.Le dispositif expérimental permet l'observation du film. Une combinaison originale de méthodes optiques permet également de mesurer sa longueur et son épaisseur, et de reconstruire son profil 3D à chaque instant. Nous pouvons suivre l'évolution du film tout au long de sa durée de vie, et ainsi analyser son comportement dynamique. Le film est presque plat (pente inférieure à 0,1°). Sur toute sa longueur, qui est de quelques centimètres, cela correspond à une variation de son épaisseur de moitié, la valeur moyenne étant de 50 microns. Sous l'effet du chauffage, le film se rétracte progressivement. Dès le début de son évaporation, un bourrelet de démouillage est formé sur le pourtour du film, près de la ligne triple. L'apparition de ce bourrelet est caractéristique d'un démouillage visqueux sous conditions de non-mouillage. Ce comportement est surprenant, dans la mesure où nous avons choisi un fluide mouillant parfaitement la paroi en conditions isothermes. A l'échelle nanométrique, au plus près de la ligne triple, l'angle de contact entre le liquide et la paroi est donc très faible. Nous mesurons cependant un grand angle apparent (c'est-à-dire visible à l'échelle millimétrique), qui augmente avec la surchauffe de la paroi. Dès l'augmentation de cet angle, le bourrelet de démouillage se forme, et le film se rétracte. Ce phénomène est expliqué par l'évaporation à l'échelle microscopique. Les résultats expérimentaux sont en accord quantitatif avec la théorie développée par d'autres chercheursWe experimentally study the behavior of liquid films - so called Landau-Levich films - when they evaporate in their pure vapor atmosphere.The dynamics of this film is a key parameter that rules out the functioning of Pulsating Heat Pipes (PHPs). PHPs are high conductive thermal links. Their heat transfert capability is known to be extremely high. For this reason they are promising for numerous industrial applications. Their geometry is simple. It is a capillary tube bent in several branches that meander between a hot part (called evaporator) and a cold part (called condenser), and filled up with a pure two-phase fluid. When the temperature difference between evaporator and condenser exceeds a certain threshold, gas bubbles and liquid plugs begin to oscillate spontaneously back and forth inside the tube and PHP starts transferring the heat.Our experimental setup features the simplest, single branch PHP. A liquid/vapor interface oscillates in a tube. It deposits a liquid film at each passage. We focus first on the mecanism which makes possible self-sustained interface oscillations and defines its frequency. The obtained motion equation accounts for the viscous dissipation caused by oscillatory flow. In existing PHP modelling, a laminar flow is supposed. Yet, our approach shows that the assumption of weakly inertial flow is preferable and leads to a dissipation rate twice larger that the Poiseuille flow.The experimental setup allows the film visualization. An original combination of optical measurement techniques lets us measure the film length, thickness and 3D-profile at all times. The film evolution has been measured during its whole lifetime. The film is nearly flat (its slope is smaller than 0,1°). The film length is of several centimeters, and the average thickness is 50 microns. Thus, along the total length, its thickness decreases by half. Under heating conditions, the film gradually recedes. A dewetting ridge is formed, near the triple contact line. Such a behavior is typical under non-wetting conditions. At the nanometric scale the contact angle between the liquid and the solid wall is very low. However, we measure a large apparent contact angle (visible at the millimetric scale) which increases with the wall superheating. Once this angle increases, the dewetting ridge is formed and the film recedes. The large apparent contact angle is explained by evaporation in the microscopic vicinity of the contact line. The measured apparent contact angle value agrees quantitatively with theoretical results obtained by other researchers
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Mcalinden, Audrey. "Structure and biosynthesis of proteoglycans and non-collagenous proteins in human meniscus." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287395.
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Pozzi, Antonio. "The menisci of the canine stifle: function in load transmission and stability." The Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=osu1400073280.
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Moavenian, Arash. "Development and characterisation of a fibre-embedded collagen-gag scaffold for meniscal repair." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610722.
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Farinaccio, Rocco. "An experimental and numerical study of the mechanical response of the knee menisci /." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=55630.
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Stapleton, Thomas William. "Development and Characterisation of an Acellular Porcine Medial Meniscus for use in Tissue Engineering." Thesis, University of Leeds, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.489839.
Full textAbstract:
The meniscus is a fibrocartilage structure found within the knee joint whose functions. include; stress distribution, load transmission, stability and lubrication ofthe joint. Demand for a suitable, 'off the shelf meniscal replacementhas increased considerably due to the rising number of injuries to the knee. This predisposition to meniscal injury relates to the limited vascularisation of the tissue resulting in restricted access of necessary repair factors. Damage to the avascular areas of the meniscus may lead to loss of function, compromising the tribological function of the knee joint. Allografts represent the gold standard in meniscal replacement, but problems related to foreign body reaction, sizing/shrinkage of the implant and lack ofchondroprotection, have yet to be solved. Synthetic products such as the Collagen Meniscal Implant™ are available which allow repair of large defects, however, this only functions when the exterior meniscal rim is intact and has been associated with poor biomechanical functioning. The overall aim of this project was to develop and evaluate the potential ofan acellular porcine medial meniscus for use as a biological matrix for a tissue engineered meniscal substitute. Following several iterations, whole porcine medial menisci were decellularised by subjecting the tissue to freeze thaw cycles, incubation in hypotonic tris buffer, 0.15% (w/v) sodium dodecyl sulfate in hypotonic buffer plus protease inhibitors, nucleases, hypertonic buffer followed by disinfection using 0.1% (v/v) peracetic acid and final washing in , phosphate buffered saline. The presence or absence ofcells was confirmed histologically, whilst DNA levels were qualitatively and quantitatively assessed using a range of molecular techniques including agarose gel electrophoresis and nano-spectrophotometry (amount ofDNA). Histological analysis demonstrated an absence of cells within the decellularised tissue whilst DNA levels were less than 2 ng.mg-I . Histologica.l, immunohistochemical and biochemical analysis (collagen and glycosaminoglycans) of the decellularised tissue in comparison to the fresh porcine medial meniscal tissue confirmed the retention of the major structural proteins (collagen: fresh, 83.4% (± 13.9,95% confidence limits [CLl) (w/w); decellularised, 74.3% (± 21.7,95% iii CL). There was however a 59.4% loss ofglycosaminoglycans as determined by the sulfated/carboxylated sugar assay. In addition, electron microscopy allowed visualisation of areas ofsynovial-like membrane damage following decellularisation. Biomechanical properties were determined by indentation and uni-axial tensile tests which confirmed the' retention of biomechanical function following decellularisation. Biocompatibility of the acellular scaffold was determined using in vitro contactand extract cytotoxicity tests. Unfortunately, deep meniscal tissue was found to be cytotoxic. Modifications to the original decellularisation protocol were incorporated to overcome this problem. These included, reduced sodium dodecyl sulfate concentration (0.1% (w/v)), reduced detergent wash temperature (45°C) and extended terminal buffer wash. Consequently, decellularised tissue and extracts were found not to be cytotoxic to cells. Residual sodium dodecyl sulfate present within the acellular scaffold was determined using radio labelled 14C sodium dodecyl sulphate (0.022% (± 0.08, 95% CL) (w/w) SDS), whilst differential scanning calorimetry demonstrated retention of the thermal stability of the decelhilarised meniscus (denaturation enthalpy: fresh outer meniscus, 510.4 J.g-1 (± 153.19, 95% CL); fresh inner meniscus 399.23 Ig-I (± 99.4, 95% CL);--deceIlularised outer meniscus, 492 J.g-1 (± 73.99, 95% CL), decellularised outer meniscus, 283.86 J.g-1 (± 115.75,95% CL). Immunohistochemistry and antibody adsorption assays showed no evidence ofthe expression of the major antigenic epitope, galactose-a-I,3-galactose in the decellularised porcine medial meniscus. The biocompatibility of the acellular scaffold was assessed in vivo by subcutaneous implantation into galactosyl-transferase knockout mice. The explanted tissue was assessed for foreign body response (capsule thickness), cellular _infiltr~te phenotype (F4/80, CD3, CD4, CD34 and C3c), as well as the presence of antigalactose- a-I,3-galactose antibodies in the mouse serum. A non-specific foreign-body response was observed following implantation of the decellularised porcine medial meniscal tissue. Preliminary investigations into in vitro recellularisation of the acellular medial meniscal scaffold demonstrated the successful attachment ofprimary human dermal fibroblasts and primary porcine meniscal cells. In addition, primary human dermal fibroblasts were able to iv infiltrate the scaffold following seven days in culture. Studies into the potential incorporation of bone blocks demonstrated almost complete cell removal following application of the established decellularisation treatment, whilst the galactose-a-l ,3galactose epitope was not detected by immunohistochemistry and antibody adsorption assay. In conclusion, this study has generated preliminary results into the production of a biocompatible, biomechanically functional scaffold which has excellent potential for development ofa tissue engineered solution to meniscal repair.
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Rao, Manoj. "Thermo-hydrodynamics of an extended meniscus as unit-cell approach of pulsating heat pipe." Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0080/document.
Full textAbstract:
Ce travail fait une tentative pour expliquer les oscillations induites thermiquement auto-entretenue d'un système à deux phases constitué d'un liquide-vapeur confinée ménisque isolé (un bouchon de liquide unique attenant à une bulle de vapeur) à l'intérieur d'un tube capillaire circulaire, la longueur du tube être exposé à un gradient de température net, créant ainsi un cycle continu de l'évaporation et la condensation. Ce système représente la simple « unité-cellule" version d'un caloduc oscillant (PHP). La compréhension fondamentale de son comportement de transport menant à oscillations auto-soutenue est essentielle pour la construction des modèles mathématiques jusque-là inexistants du système PHP complet. Tout d'abord, la visualisation des oscillations de l'unité de cellules a été effectuée dans des conditions aux limites thermiques contrôlées. Ici, une compréhension nouvelle et unique de la dynamique du système a été atteint par une synchronisation en temps réel de la mesure de pression interne avec la vidéographie haute vitesse qui a été utilisé pour visualiser et enregistrer les oscillations du ménisque et le mince film de liquide qui est mis sur le mur lorsque le ménisque quitte l'évaporateur. Un modèle numérique a été développé pour le système constitué par un bouchon de vapeur et un bouchon de liquide oscillant dans un tube fermé à une extrémité et relié à un réservoir à une pression constante à l'autre extrémité. Le principe de modélisation avait été posé lors de travaux antérieurs. Quelques modifications ont été jamais moins introduites dans ce travail pour prendre en compte les particularités de la nouvelle expérimental et pour améliorer le liquide modèle film de l'évaporation à la lumière des résultats expérimentaux. Une étude paramétrique a également été réalisée pour comprendre les implications des différents facteurs sur le fonctionnement d'un tel systèmeThis work makes an attempt to explain the self-sustained thermally-induced oscillations of a two-phase system consisting of an isolated confined liquid–vapour meniscus (a single liquid plug adjoining a vapour bubble) inside a circular capillary tube, the tube length being exposed to a net temperature gradient, thereby creating a continuous cycle of evaporation and condensation. This system represents the simplest ‘unit-cell’ version of a Pulsating Heat Pipe (PHP). The fundamental understanding of its transport behavior leading to self-sustained oscillations is vital for building the hitherto non-existent mathematical models of the complete PHP system. First, visualization of the oscillations of the unit-cell has been done under controlled thermal boundary conditions. Here, a unique and novel understanding of the system dynamics has been achieved by real-time synchronization of the internal pressure measurement with high-speed videography that was used to visualize and record the meniscus oscillations and the thin liquid film that is laid on the wall when the meniscus leaves the evaporator. A numerical model was developed for the system consisting of a vapour plug and a liquid slug oscillating in a tube closed at one end and connected to a reservoir at a constant pressure at the other end. The modeling principle had been posed in previous work. Some modifications were never the less introduced in this work to take into account the peculiarities of the new experimental set-up and to improve the liquid film evaporation model in the light of the experimental results. Also a parametric study was carried out to understand the implications of the various factors on the working of such system