Made available in DSpace on 2014-06-11T19:31:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-06-15Bitstream added on 2014-06-13T19:20:09Z : No. of bitstreams: 1 silva_a_dr_jabo.pdf: 565683 bytes, checksum: 80bdf869b7e9328e066b0dd4ffc4fdf6 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A descrição morfológica da paca pode facilitar sua exploração econômica racional e preservação da espécie. Além disso, devido ao interesse dos pesquisadores por novos modelos experimentais de cirurgia, em especial para reconstrução das estruturas do joelho, objetivou-se com o presente estudo, descrever a anatomia do joelho da paca. Neste contexto, a articulação do joelho foi dissecada para identificar as estruturas presentes; foi verificada a ocorrência de tecido ósseo nos meniscos, e realizada análise histológica e ultraestrutural dos ligamentos colaterais e meniscos. No joelho da paca foram identificados os ligamentos cruzados cranial e caudal; o ligamento meniscofemoral; os ligamentos colaterais lateral e medial; os ligamentos meniscotibiais craniais dos meniscos medial e lateral; o ligamento meniscotibial caudal do menisco medial; o ligamento patelar; a patela; os ossos sesamóides do músculo gastrocnêmio lateral e medial, e os meniscos lateral e medial. Os ligamentos colaterais são constituídos por feixes de fibras colágenas arranjadas paralelamente e com trajeto ondulado. Os fibroblastos formavam fileiras paralelas às fibras colágenas, dos ligamentos colaterais, com citoplasma imperceptível à avaliação por microscopia de luz, mas, em análise ultraestrutural verificou-se vários prolongamentos citoplasmáticos. Os meniscos destes animais são fibrocartilaginosos e apresentam na região cranial uma ossificação. As estruturas presentes no joelho da paca assemelham-se aos dos animais domésticos, roedores e lagomorfos. Os ligamentos colaterais e os meniscos são estruturalmente semelhantes aos ligamentos e meniscos do joelho dos animais domésticos, roedores e lagomorfos. Porém, o menisco da paca apresenta lúnula / Paca morphological description may facilitate their rational economical exploitation and specie preservation. The researches interest by novel surgical experimental models, focus specially by joint stifle reconstruction, also motivated the present study in describing the anatomy of the paca stifle. In this context, the stifle joint was dissected in order to identify the structures. It was observed tissue bone in meniscus and the histological and ultrastructural analysis of collateral ligament and menisci were performed. The cranial and caudal cruciate ligaments; the meniscofemoral ligament; the lateral and medial collateral ligaments; cranial meniscotibial ligaments of the medial and lateral menisci; caudal meniscotibial ligament of the medial meniscus; patellar ligament; patella, the lateral and medial sesamoid bones of the gastrocnemius muscle and the lateral and medial menisci. The collateral ligaments are composed of crimp collagen fiber bundles arranged in parallel. The fibroblasts were aligned with the collagen fibers. The cytoplasm was unable to be noticed by light microscopy, but ultrastructural analysis showed a large amount of citoplasmatic projections. The menisci of these animals are fibrocartilaginous with bone tissue cranially. The paca stifle joint structures are similar to the domestic animals, rodents and lagomorphs. Collateral ligaments and menisci are structurally similar to the domestic animals, rodents and lagomorphs. However the paca meniscus has lunula

A espécie asinina (E. asinus) teve sua origem há milhares de anos, se desenvolvendo a partir de um tronco comum ao do eqüino doméstico que conhecemos. Vem passando por um processo adaptativo, apresentando características distintas, quando os observamos em diversas partes do planeta. Na região nordeste do Brasil, desenvolve um papel fundamental, influenciando diretamente na renda das famílias locais. Tendo em vista o grande número de afecções locomotoras e a falta de cuidados a que estão submetidos, realizou-se um estudo anatômico e radiográfico da região distal de seus membros torácicos, buscando-se subsídios a prática clínica e cirúrgica dedicada a esses animais, bem como a compreensão de sua maior resistência a lesões locomotoras, quando comparado ao eqüino. A avaliação anatômica revelou características musculares semelhantes as já descritas para eqüinos. O exame radiográfico evidenciou lesões severas, caracterizadas por osteíte podal e áreas de reabsorção óssea e remodelamento na margem solear, associadas à rotação da falange distal. Ainda na avaliação radiográfica, caracterizaram-se os principais vasos arteriais dessa região através de técnica angiográfica. Não se observou correlação entre o ângulo de inclinação da muralha do casco e falange distal, com a área de secção transversal dos tendões dos músculos flexores. As maiores secções transversais para o tendão flexor digital superficial, profundo e interósseo, mostraram coincidência com os pontos de maior estresse articular, caracterizando, assim, a resistência dos asininos à lesões nestas estruturas em seu aparelho locomotor. / The asinine species was originated thousands of years ago from the same branch of the domestic equine. The asinine have been undergoing to a great adaptation resulting in different characteristics of each population of asinine around the world. In the northeast region of Brazil, they play an essential role in the income of the local families. Due to a large number of locomotor disorders and a lack of professional care, an anatomic and radiographic study of the distal forelimb region of the asinine was carried out in order to gather information to improve the clinical and surgical practice in this species, and to explain the less susceptibility to locomotor disorders compared to equines. The anatomical study showed that asinine have similar muscular characteristics already described for equines. The radiographic exam showed severe lesions, characterized by pedal osteitis, bone reabsorption areas and remodelling of sole margin associated to the distal phalanx rotation. The radiographic study also showed the characterization of the main arterial vessels. No significant correlation was observed between the angle of the hoof wall and the angle of the distal phalanx with the cross section area of the flexor tendons. The larger cross section areas of the superficial digital flexor tendon, deep digital flexor tendon and interosseus tendon were coincidental with the great articular stress, explaining the greater resistance of the asinines to lesions in those structures of their locomotor apparatus.

The research presented in this thesis focuses on understanding the biomechanical effects of various cranial features that are often ignored in finite element models (FEMs) because their size, position, and complex shapes make them difficult to model. Specifically, this work examines the effects of the alveoli (tooth sockets), periodontal ligament, and squamosal suture on the stress and strain distributions in a cranium under masticatory and dynamic tooth loads. Results from this research will help determine if these features have a significant effect on stress and strain patterns and will yield guidelines as to if or under what conditions they need to be modeled in future FE skull model analyses. As part of this research, three sets of FEMs were developed to address a hypothesis focusing on each cranial feature. The first set of models examined the effect of the tooth sockets on the stress and strain distributions in a cranium under static biting conditions to determine if improperly modeled sockets produce strong global effects in craniofacial regions. The second set of models were used to assess the effect of the PDL's material behavior on the stresses and strains in a cranium under static biting and dynamic tooth loading conditions to determine if the PDL plays an important role in reducing stresses and strains in a model. The final set of models were used to determine the effect of the squamosal suture size on the stresses and strain energies in a cranium under static biting conditions to see if an increase in suture size decreases the risk of separation of the temporal bone from the parietal bone. Results for all analyses indicate the effects of the cranial features are local (i.e. within the vicinity of the feature), with no meaningful global effects. This suggests the sockets, PDL, and squamosal suture do not play an important role in global stress and strain distributions in a cranium under masticatory and dynamic tooth loads. Therefore, it may be safe to ignore the sockets, PDLs, and squamosal sutures during the FE modeling process if the objective of the analysis is to understand global stress and strain patterns.

No description available.

Desmopathy of the collateral ligament of the distal interphalangeal joint is a common cause of lameness in the horse and carries a poor prognosis for soundness. Intralesional treatment has been suggested as a way to improve outcome; however, limited reports describe methods for injecting this ligament. This study compares the accuracy of injecting the collateral ligament of the distal interphalangeal joint using magnetic resonance imaging (MRI) versus radiographic guidance. Equine cadaver digit pairs (n=10) were divided by random assignment to injection of the ligament by either technique and assessed using post-injection MRI or gross sections. Images from the proximal, middle, and distal portions of the ligament were blindly evaluated for successful injection. McNemar\'s test was performed to determine statistical difference between injection techniques. Fisher\'s exact test was used to evaluate number of injection attempts and injection of the medial or lateral collateral ligament. MRI-guided injection was successful more frequently than radiographic-guided injection on post-injection MRI (24 of 30 versus 9 of 30; p=0.0006) and gross sections (26 of 30 versus 13 of 30; p=0.0008). At each level of the ligament (proximal, middle, and distal), MRI-guided injection resulted in more successful injections than radiographic guidance. Statistical significance occurred at the proximal aspect of the collateral ligament based on post-injection MRI (p=0.0143) and the middle portion of the ligament based on gross sections (p=0.0253). Based on these results, injection guided by standing, low-field MRI should be considered an option for delivering intralesional regenerative therapy to horses with desmopathy of these collateral ligaments. / Master of Science

Collagenous tissues such as ligaments and tendons are viscoelastic materials. They exhibit a slow continuous increase in strain over time, or creep, when subjected to a constant stress and a slow continuous decrease in stress over time, or stress relaxation, when subjected to a constant strain. Moreover, the loading and unloading stress-strain curves are different when the tissues are subjected to cyclic loading, showing hysteresis and softening phenomena. The micro-structural origin of the viscoelasticity of these tissues is still unknown and the subject of debate among experts in biomechanics. Therefore, formulating viscoelastic models by accounting for the mechanical contributions of the structural components of these tissues can help in understanding the genesis of viscoelasticity. A nonlinear viscoelastic modeling framework has been developed to describe the elastic and viscoelastic properties of ligaments and tendons by considering their main structural components, the collagen fibers and proteoglycan-rich matrix. The mathematical models derived within this framework can illustrate the tensile behavior, stress relaxation and creep by as suming that the collagen fibers are elastic and the surrounding proteoglycan-rich matrix is viscoelastic. The collagen fibers are represented by linear elastic springs that are engaged to support load at different values of the tissue's strain according to a Weibull distribution function. The mechanical contribution of the matrix is introduced via a Maxwell-type viscoelastic element arranged in parallel with the collagen fibers. According to the proposed mathematical framework, both the collagen fibers and the proteoglycan-rich matrix are responsible for resisting tensile loads. However, the collagen fibers play a significant role in creep while the proteoglycan-rich matrix has a dominant role in stress relaxation. The model parameters that define the stress relaxation and strain stiffening phenomena are estimated by using published experimental on rabbit medial collateral ligaments and are then used to predict creep. The above modeling framework has been also extended to capture the in uence of preconditioning on the mechanical properties of ligaments and tendons. The stress softening and decrease in hysteresis that are observed during successive loading cycles in preconditioning are assumed to be determined by a decrease in the elastic properties of the collagen fibers and proteoglycan-rich matrix. Preliminary data collected on stress relaxation and preconditioning on rat medial collateral ligaments by collaborators are used to evaluate the model parameters and analyze its predictions. The elastic and viscoelastic properties of single collagen fibers are studied by formulating a nonlinear viscoelastic framework by accounting for their main components: microfibrils, cross-links and proteoglycan-rich matrix. The model illustrates tensile behavior and stress relaxation of a single collagen fiber by assuming that the microfibrils and the cross-links are elastic and the surrounding proteoglycan-rich matrix is viscoelastic. The mechanical contribution of the microfibrils is included via a linear elastic spring while the cross-links are represented by linear elastic springs that progressively fail at different values of the tissue's strain according to an exponential distribution function. The matrix is defined by linear dashpots arranged in parallel with each single spring that represents an individual cross-link. The viscous properties of the matrix associated with the unbroken and broken cross-links are assumed to have different values. In the model formulation, the microfibrils and the cross-links are assumed to determine the elastic response of the fibers while the proteoglycan-rich matrix determines the stress relaxation. Microfibrils, cross-links and the proteoglycan-rich matrix are responsible for resisting the loading force during tensile behavior. Experimental data collected by performing incremental stress relaxation tests by other investigators on reconstituted rat tail tendons are used to estimate the parameters in the model and evaluate its performance. / Ph. D.

Lam, Mak Ham. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 110-131). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

O objetivo deste trabalho foi avaliar a importância relativa dos diferentes estabilizadores estáticos do canto póstero-lateral do joelho. Para isso foram utilizados 10 joelhos de cadáveres que foram submetidos a testes biomecânicos com a aplicação de forças para a deformação em varo e em rotação externa. Os joelhos foram testados em quatro situações diferentes e sempre na mesma seqüência: com a articulação íntegra, após a secção do ligamento colateral lateral, após a secção do ligamento colateral lateral e do complexo poplíteo-fibular (tendão do poplíteo + ligamento poplíteo-fibular) e após a secção do ligamento colateral lateral, do complexo poplíteo-fibular e da cápsula póstero-lateral. Os testes foram feitos com os joelhos em extensão, em 30 e em 60 graus de flexão. Os parâmetros estudados foram a deformação angular e a rigidez durante a aplicação do momento de flexão (varo) de 15 N.m e do momento de torção (rotação externa) de 6 N.m. A análise estatística foi realizada com o teste de comparações múltiplas de Tukey. Através da análise dos resultados obtidos com os testes biomecânicos e comparando os valores obtidos nas quatro situações estudadas entre si, foi possível interpretar a função específica de cada estrutura do canto póstero-lateral do joelho, em cada ângulo de flexão testado. Neste estudo, o ligamento colateral lateral foi importante na estabilização do joelho para o varo em extensão, em 30 e em 60 graus de flexão. O complexo poplíteo-fibular foi a estrutura mais importante na estabilização do joelho para a rotação externa, dentre as estruturas avaliadas, atuando em todos os ângulos de flexão testados. Além disto, complexo poplíteo-fibular foi importante na estabilização para o varo quando o joelho se encontrava em 30 e em 60 graus de flexão. Já a cápsula póstero-lateral foi importante na estabilização para o varo e para a rotação externa quando o joelho se encontrava em extensão, perdendo sua função à medida que o joelho foi flexionado. Em 30 graus de flexão, a cápsula póstero-lateral foi importante apenas para a estabilização em varo do joelho. / The purpose of this study was to evaluate, in cadaver knees, the relative importance of the different static stabilizers of the posterolateral corner of the knee. Tests were performed with the application of a varus and external rotation force to the knee in extension, 30 and 60 degrees of flexion, using 10 cadaver knees. The forces were applied initially to an intact knee and then repeated after a selective sectioning of the ligaments: section of the lateral collateral ligament; section of the lateral collateral ligament and the popliteofibular complex; and section of the lateral collateral ligament, the popliteofibular complex and the posterolateral capsule. The parameters studied were the angular deformity and rigidity while the knees were being submitted to a 15 newton-meter varus torque and a 6 newton-meter external tibial torque. Statistical analysis was performed using the ANOVA and Tukey tests. Our findings showed that the lateral collateral ligament was important in varus stability at 0, 30 and 60 degrees; the popliteus-fibular complex was the most important structure in external rotation stability at all angles of flexion and was also important for varus stability at 30 and 60 degrees; the posterolateral capsule was important for varus stability at 0 and 30 degrees, and for external rotation stability in extension.

Com o objetivo de avaliar as modificações morfo-funcionais que ocorrem durante a fase preparatória do parto de caprinos, 18 fêmeas da raça Saanen foram examinadas duas vezes ao dia nos últimos 20 dias de gestação e, ao final do experimento, foram agrupadas segundo o momento que antecedia o parto, da seguinte forma: 16, 8, 6, 4 ,3, 2, 1 ½ , 1, ½ dia antes do parto e imediatamente antes da parição. Também foram colhidas amostras de plasma sangüíneo e de soro lácteo para a dosagem de progesterona, estradiol e cortisol e dos teores lácteos de cálcio. Durante o exame clínico foram avaliados os seguintes parâmetros: temperatura corpórea; relaxamento e movimentação dos Ligamentos Sacro-Isquiáticos; distensão e plenitude da glândula mamária e dos tetos; aspecto da secreção láctea pré-colostral e concentração de cálcio nela presente; modificações da vulva e do fluxo vaginal e determinação dos teores plasmáticos de cortisol, progesterona e estradiol. Ocorreram graduais relaxamento e aumento da movimentação dos Ligamentos Sacro-Isquiáticos, observados com maior intensidade a partir de 24 horas antes da parição, com grau máximo observado no momento do parto. Associada ao relaxamento e movimentação dos ligamentos, ocorreu diminuição gradual na capacidade dos animais em movimentar a cauda. A glândula mamária e os tetos foram tornando-se cada vez mais distendidos e plenos de acordo com a proximidade do momento da parição, sendo que a presença de edema na glândula mamária foi esporádica. A freqüência de cabras cuja secreção láctea foi classificada como colostro aumentou com a aproximação do parto, assim como os teores de cálcio na secreção pré-colostral. Houve um aumento significativo do fluxo vaginal nos animais examinados imediatamente antes da parição. O perfil hormonal sofreu influência da fase preparatória do parto, sendo que ocorreu diminuição dos teores plasmáticos médios de progesterona e aumento dos teores de estradiol e cortisol à medida que a parição se aproximava. A temperatura corpórea, o tamanho e o edema de vulva, o grau de flexibilidade da base da cauda e a coloração da mucosa vaginal não sofreram influência da fase preparatóra do parto. / With the aim to evaluate the morpho-functional changes of the caprine\'s parturition preparatory phase, 18 Saanen does were examined twice a day within the 20 finishing days of gestation and at the end of the experiment they were grouped according to the moment that preceded the birth (16, 8, 6, 4, 3, 2, 1 ½, 1, ½ days before parturition and immediately before labor). There were also picked samples of sanguine plasma and milky serum for the progesterone, oestradiol and cortisol dosage and milky calcium determinations. During the clinical exam the following parameters were evaluated: corporal temperature; relaxation and movement of the Sacrosciatic Ligaments; movement and flexibility of the tail; distention and filling of the udder and teats; appearance of the pre-colostral milky secretion and its calcium concentration; modifications of the vulva and vaginal discharge and determination of the plasmatic values of progesterone, oestradiol and cortisol. Gradual relaxation and increase of movement of the Sacrosciatic Ligaments occurred, observed with larger intensity starting from 24 hours before parturition, with maximum degree observed in the moment of the birth. A gradual decrease in the animals\' capacity on tail movement was observed associated to the relaxation and movement of the Sacrosciatic Ligaments. The mammary gland and teats became more distended and full in agreement with the proximity of the moment of parturition and the edema presence in the mammary gland was sporadic. The frequency of goats whose milky secretion was classified as colostrum increased with the approach of the labor, as well as the calcium tenors in the pre-colostral secretion. There was a significant increase of the vaginal discharge in the animals examined immediately before parturition. The hormonal profile suffered influence of the preparatory phase of labor, occurring decrease of the medium plasmatic tenors of progesterone and increase of the oestradiol and cortisol tenors as the parturition approaches. The corporal temperature, the size and vulva edema, the degree of flexibility of the tail and the coloration of vaginal mucous membrane didn\'t suffer influence of the preparatory stage of labor.

Twenty five porcine knee collateral ligaments were tested to determine the dynamic failure properties of ligaments. A test fixture, to be placed in a drop tower, was designed to apply an axial impulsive impact load to a porcine bone-ligament-bone complex. The applied strain rates ranged from 0.005s-1 to 145s-1. The data from the impact tests was analyzed using the method of linear regression to construct predictive model equations capable of forecasting the failure load and failure stress of a ligament subjected to a specific strain rate. 73% of the ligaments tested failed via tibial avulsion while the remaining ligaments failed via mid-substance tearing. The failure: load, strain and stress all increased with the applied strain rate. Further an interesting correlation between geometric ratios, namely the initial length divided by the initial cross sectional area and vice versa, and the failure load and stress were identified. Using this information, model equations were developed that predict the failure stresses based on the load and strain rate. The motivation for this study was to develop failure properties that could be used in an LSDYNA finite element model of the human lower extremities based on the understanding that the properties of porcine knee collateral ligaments would be similar to human ligaments. The properties developed in this study can be used to estimate the human response in high speed frontal automotive collisions.