<p>Osteoporosis and fractures are debilitating skeletal problems. Accumulating the highest peak bone mass in both cortical and trabecular bone (Tb) as well as developing strong Tb microarchitecture play an integral role in preventing bone loss and osteoporotic fractures later in life. Because Tb is modulated by genetics (G) and environment (e.g. diet, D), my dissertation research focuses on the influence of dietary calcium (Ca) intake, genetics as well as GxD interaction controlling Tb phenotypes in two clinically relevant skeletal sites, i.e. the femur and the L5 vertebra. Male mice from 11 in bred lines and 51 BXD recombinant inbred (RI) lines were fed either adequate (Basal, 0.5%) or low (0.25%) Ca diets from 4-12 weeks of age. We used micro-computed tomography to measure Tb mass and microarchitecture phenotypes. We systematically proved that there are site-specific effects of diet, genetic, and GxD interactions influencing Tb phenotypes. This indicates that there are unique genetic effects modulating Tb at each bone site. Therefore, we conducted a genetic mapping experiment using the 51 BXD RI lines separately for each bone site. We coupled genetic mapping analysis with bioinformatics analysis to identify novel genetic variation and candidate genes accounting for the variation in each phenotypes. The findings from this work serve as a foundation for future research to identify novel pathways and genes underlying the development of Tb as well as an adaptation to Ca insufficiency.</p> <br> <p> </p>

Les buts de cette thèse étaient de définir les déterminants de la santé osseuse chez les jeunes femmes en surpoids et obèses et d'explorer les effets de deux programmes longitudinaux d'entraînement physique (force vs. endurance) sur les paramètres osseux chez les jeunes femmes en surpoids et obèses. Deux études préliminaires et six études principales ont été menées. La première étude préliminaire a montré que la VO2 max (L/mn) est un déterminant positif de la masse osseuse chez les enfants en surpoids. La deuxième étude préliminaire a démontré que l'IMC est un déterminant négatif du CSI, du BSI et de l'ISI chez les jeunes femmes. La première étude principale a montré que l'obésité est associée à de faibles valeurs de CSI, de BSI et d'ISI chez les jeunes femmes. La deuxième étude principale a montré que la VO2 max (ml/mn/kg) est positivement corrélée au CSI et à l'ISI chez les jeunes femmes. La troisième et la quatrième étude ont montré que la surcharge pondérale est associée à une augmentation du CMO et de la DMO mais pas du TBS et que le TBS est corrélé positivement à la VO2 max (L/mn). La cinquième étude principale chez 68 jeunes femmes en surpoids et obèses a montré que la détente verticale, la VO2 max (L/mn), la puissance maximale (watts) et la force maximale en demi-squat sont positivement corrélées aux paramètres osseux chez les jeunes femmes en surpoids et obèses. La sixième étude principale a montré que les deux types d'entrainement physique (force et endurance) sont efficaces pour augmenter le CMO CE et la DMO lombaire et diminuer le poids et la masse grasse. L'entrainement de force était aussi efficace pour l'augmentation du TBS et les indices de résistance osseuse du col fémoral (CSI, BSI et ISI). / The aims of this thesis were to define the determinants of bone health in young overweight and obese men and to explore the effects of two physical training programs (strength vs. endurance) on bone parameters in young overweight and obese women. Two preliminary studies and six main studies have been conducted. The first preliminary study has shown that VO2 max (L/mn) is a positive determinant of bone mass in overweight children. The second preliminary study has shown that BMI is a negative determinant of CSI, BSI and ISI in young women. The first main study has shown that obesity is associated with lower CSI, BSI and ISI values in young women. The second main study has shown that VO2 max (L/mn) is positively correlated to CSI and ISI in young women. The third and the fourth study have shown that being overweight is associated with higher BMC and BMD values but not with TBS values and that TBS is positively associated with VO2 max (L/mn). The fifth main study conducted on 68 young overweight and obese women has shown that vertical jump, VO2 max (L/min), maximal power (watts) and 1-RM half-squat are positively correlated with bone parameters in overweight and obese adult women. The sixth main study has shown that the two training programs (strength and endurance) are effective to increase whole body BMC and lumbar spine BMD, and to decrease body weight and fat mass. Strength training was also effective to increase TBS and composite indices of femoral neck strength (CSI, BSI and ISI)

Trabecular bone has a complex and porous microstructure. This study develops approaches to determine the mechanical behaviour of this material at the macroscopic level through the use of homogenisation-based multiscale methods using micro-finite element simulations. In homogenisation-based finite element methods, a simulation involving a representative volume element of the microstructure of the considered material is performed with a specific set of boundary conditions. The macroscopic stresses and strains are retrieved as averaged quantities defined over this domain. Most of the homogenisation-based work on trabecular bone has been performed to study its macroscopic elastic regime, and therefore define its constant macroscopic stiffness tensor. The rod and plate-shaped microstructure of trabecular bone can be precisely identified with advanced scanning tools, such as micro-computed tomography devices. Taking into account the size requirements to achieve a certain independence of boundary conditions for trabecular bone in a homogenisation-based multiscale setting, the resulting stack of images can have around ten million solid voxels after binarisation. Although a completely linear finite element simulation with such a large system may be feasible with commercial packages (with the proper time and memory requirements), it is not possible to perform a nonlinear simulation for such a mesh in a reasonable time frame, and the amount of required memory may not be available. A highly scalable parallel driver program which solves finite strain elastoplastic systems was developed within the framework of the existing parallel code ParaFEM. This code was used throughout this study to evaluate the yield and post-yield properties of trabecular bone. It was run on cutting edge high performance computing platforms (BlueGene/Q at the Hartree Centre, Science and Technology Facilities Council; and ARCHER, UK National Supercomputing Service, at Edinburgh Parallel Computing Centre). Micro-finite element simulations require definition of properties at the microscopic scale and it is unclear how these properties affect the macroscopic response. This study examines the effect of compressive hydrostatic yield at the microscopic scale on the macroscopic behaviour. Two different microscopic yield criteria, one permitting yielding at compressive hydrostatic stresses and the other not, were considered. A large number of load cases were examined. It was found that these two microscopic yield criteria only influence macroscopic yield behaviour in load scenarios which are compression-dominated; for other load cases, macroscopic response is insensitive to the choice of the microscopic yield criterion, provided it has an appropriate strength asymmetry. Also, in compression-dominated load cases, high density bone is much more sensitive as it is more like a continuum, resulting in the microscopic properties being more directly upscaled. Only a few previous studies have employed homogenisation to evaluate the macroscopic yield criterion of trabecular bone. However, they either used a simplified microscopic yield surface or examined only a small number of load cases. A thorough multiaxial evaluation of the macroscopic yield surface was performed by applying a wide range of loading scenarios (160 load cases) on trabecular bone samples. Closed-form yield surfaces with different symmetries (isotropy, orthotropy and full anisotropy) were fitted to the numerically obtained macroscopic yield points in strain space, and the fitting errors were evaluated in detail for different subsets of load cases. Although orthotropy and full anisotropy showed the smallest fitting errors, they were not significantly superior to the isotropic fit. Thus, isotropy in strain space presents itself as the most suitable option due to the simplicity of its implementation. The study showed that fitting errors do depend on the chosen set of load cases and that shear load cases are extremely important as it was found that even for these highly aligned samples, trabecular bone presents some degree of shear asymmetry, i.e. different strength in clockwise and counter-clockwise shear directions. There have been no previous attempts to evaluate the post-yield behaviour of trabecular bone through homogenisation-based studies on detailed micro-finite element trabecular bone meshes. A damage and plasticity constitutive law for the microscale based on existing data in the literature was considered. A homogenisation-based multiscale approach was used to evaluate the hardening and stiffness reduction at the macroscale when uniaxial load scenarios are applied to trabecular bone samples, for a small range of plastic strain Euclidean norms. Results show that damage progression at the macroscale for trabecular bone is not isotropic, which is contrary to what has been assumed previously, and that both the evolution of the yield surface and damage are different for tension, compression and shear. Nonetheless, they can be correlated with plastic strain Euclidean norms by using linear relationships. It was also observed that macroscopic damage in a specific load case affects differently the on-axis orthotropic stiffness and the off-axis orthotropic stiffness components. The findings of this study will permit the use of a more rigorous definition of the post-elastic macroscopic behaviour of trabecular bone in finite element settings.

Nous avons évalué l'apport de l'analyse de la texture de radiographies de l'os trabéculaire sur le diagnostic de l'ostéoporose et sur le pronostic de l'arthrose. Tout d'abord, la combinaison de la densité minérale osseuse et de l'analyse de texture de la microarchitecture osseuse a été étudiée dans la perspective d'améliorer la détection des fractures ostéoporotiques. La texture a été analysée avec le paramètre fractal H et le TBS (Trabecular Bone Score) calculés sur des régions d’intérêt de radiographies du calcanéum et de densitométries osseuses aux vertèbres, respectivement. L'information supplémentaire apportée par l'analyse de texture a permis de discerner des femmes avec des fractures de fragilité dans le groupe des patientes non ostéoporotiques. Dans un second temps, des techniques de prétraitement ou de filtrage des images ont été exploitées afin d'améliorer l'analyse de la texture osseuse. L'une des dernières méthodes de décomposition variationnelle a été comparée avec des techniques classiques de filtrage. Les prétraitements améliorent certaines caractéristiques de texture, mais parmi celles-ci, le paramètre fractal H était plus robuste puisqu'il restait au même niveau de performance sans nécessiter de prétraitement. Enfin, les capacités prédictives de l'analyse de texture dans la progression de l'arthrose ont été étudiées à partir de radiographies numérisées du genou. La progression de l'arthrose a été évaluée par la variation du score radiographique de Kellgren et Lawrence à 4 ans d'intervalle. La signature fractale et l'entropie mesurées sur le compartiment tibio-fémoral latéral étaient significativement associées à la progression de la gonarthrose. / We have evaluated the added value of trabecular bone radiography's texture analysis to improve osteoporosis diagnosis and osteoarthritis prognosis. Firstly, fracture discrimination by combined Bone Mineral Density (BMD) and microarchitectural texture analysis has been studied. The Spine Trabecular Bone Score (TBS) and calcaneus mean Hurst parameter (H) has been assessed. The texture parameters have helped to classify a subset of non-osteoporotic women into a group with a higher risk of fractures. Secondly, preprocessing or filtering methods have been used to improve bone texture analysis. One of the latest variational decomposition model has been compared to classical filtering methods. Preprocessing improve some texture features but among them the fractal parameter H is more reliable since it doesn't need preprocessing to obtain the same performance. At last, the predictive ability of texture analysis with respect to knee osteoarthritis progression has been studied from digitalized radiography. The progression of knee osteoarthritis has been evaluated by the change in Kellgren and Lawrence scale at 4 years. The fractal signature and entropy assessed on lateral tibiofemoral compartment have been significantly associated with knee osteoarthritis progression.

O implante dental depende do osso de suporte para sua estabilidade e ongevidade funcional. O comportamento mecânico e a estrutura trabecular do osso afetam a interface com o implante. Tal conhecimento pode fornecer uma base para melhoramentos na função e desenho dos implantes atuais minimizando a reabsorção da crista óssea e falha na junção osso-implante. Desta forma a correta quantificação das forças que atuam sobre o sistema de implante e principalmente no osso de suporte ao qual ele está inserido é importante para o entendimento da biomecânica possibilitando que intervenções possam ser realizadas pelos profissionais visando assim à longevidade das próteses implanto-suportadas bem como dos implantes que as sustentam. Por essa razão, a proposta deste trabalho foi avaliar, com auxílio de extensômetros elétricos, se o processo laboratorial de confecção de coroas metalocerâmicas resulta em alterações das tensões no osso ao redor dos implantes. Para isto foi utilizado um modelo de poliuretano em forma de U simulando o osso mandibular com dois implantes de hexágono externo de 3,75mm de diâmetro por 13 mm de comprimento, nos quais foram fixados intermediários multi-unit. Os corpos de prova foram confeccionados com dois tipos de ligas odontológicas - Cobalto-Cromo e Paládio-Prata - e três tipos de cilindros protéticos calcinável, usinado de Cobalto-Cromo e usinado de Ouro. As leituras de deformação foram realizadas em dois momentos: 1- após a fundição das infra-estruturas e 2 após estas infra-estruturas terem recebido cobertura cerâmica. Os testes foram realizados parafusando os corpos de prova sobre os intermediários utilizando-se para isto um dispositivo eletrônico de torque com força máxima de 10 Ncm. Os resultados mostraram que, após a aplicação da cobertura cerâmica, ocorreu piora da condição de assentamento aos intermediários. O mesmo não foi detectado quando se avaliou a deformação do osso simulado, já que os valores de deformação não ndicaram diferenças antes e após a aplicação da cerâmica. / The dental implant depends on the supporting bone for its stability and functional longevity. Mechanical behavior and trabecular bone structure affect the interface with the implant. Such knowledge may provide a basis for improvements in the current implant function and design, decreasing bone crest resorption and failure at bone-implant junction. Adequate quantification of forces that act upon the implant system and mainly on the supporting bone is important for understanding the biomechanics, allowing the intervention by professionals with the purpose of achieving the longevity of implant-supported prostheses. Therefore, this work aims at evaluating, with the aid of strain gauges, whether the laboratorial process of metal ceramic crown fabrication results in changes of the tensions around the implants. A U-shaped polyurethane model simulating the mandibular bone with two 3.75-mm diameter and 13-mm length external hexagon implants were used with fixed multi-unit abutments. Specimens were prepared with two types of dental alloys - cobalt-chromium and silver-palladium - and three types of prosthetic cylinder castable plastic, prefabricated in cobalt-chromium or gold. The deformation readings were performed in two moments: 1- after framework casting and 2- after ceramic layering of the framework. The tests were performed with the framework screwed onto the abutments at 10Ncm using an electronic torque device. The results showed that the ceramic layering worsened the fit between the crowns and the abutments. The same was not detected when bone deformation was evaluated since the values were not statistically different.

A osteoporose, doença caracterizada pela redução da massa óssea e deterioração da microestrutura óssea, atinge a população idosa e afeta centenas de milhões de pessoas em todo mundo. Por manifestar-se sem causar sintoma visível, o diagnóstico da doença ocorre, na maioria dos casos após lesão ou fratura do osso. Na tentativa de detectar os sinais iniciais da doença, utilizam-se diferentes métodos de avaliação da qualidade óssea baseados na medida da densidade e da arquitetura óssea. Atualmente existe um grande interesse em estabelecer uma correlação entre as medidas de qualidade óssea com as propriedades mecânicas de resistência do osso. Uma estratégia para caracterizar o comportamento mecânico do osso consiste em obter as propriedades da macroestrutura óssea a partir das propriedades da sua microestrutura. Cowin (1985) propõe um modelo mecânico para materiais porosos elástico-lineares supondo que a função resposta mecânica do meio poroso elástico sob deformações infinitesimais é uma função isotrópica do tensor deformação infinitesimal, da fração volumétrica e do tensor textura que caracteriza a simetria do arranjo geométrico do meio poroso. Ao obter uma relação entre as componentes do tensor de elasticidade, as componentes do tensor textura e a fração volumétrica do meio poroso, o autor observa que o tensor de elasticidade obtido não fornece todos os tipos possíveis de simetria do material poroso, restringindo-se apenas à ortotropia e seus casos particulares, tais como a isotropia e a isotropia transversal. O tensor de elasticidade obtido por Cowin (1985) não descreve o comportamento local do meio poroso, pois depende explicitamente das componentes do tensor textura, o qual representa uma medida não local. Esta dissertação tem por objetivo estudar e analisar o modelo proposto por Cowin (1985). Propõe-se neste trabalho uma formulação para a função resposta de materiais porosos elástico-lineares para deformações infinitesimais que descreva o comportamento local do meio poroso. / Osteoporosis, a disease characterized by the reduction of bone mass and deterioration of bone microstructure deterioration, affects the elderly population and hundreds of millions of people worldwide. As a silent disease, its diagnosis occurs, in most cases, after injury, or, bone fracture. In an attempt to detect early signs of the disease, different methods of diagnostic imaging to obtain measures of density and bone architecture are used. Currently, there is great interest in establishing a correlation between the measurements of bone quality with the mechanical properties of bone strength. One strategy to characterize the mechanical behavior of bones is to obtain the properties of its macrostructure from the properties of its microstructure. Cowin (1985) proposes a mechanical model for porous materials by assuming that the mechanical response function of the material under infinitesimal deformation is a function of the infinitesimal deformation tensor, the volume fraction, and the texture tensor that characterizes the symmetry of the geometrical arrangement of the porous medium. By obtaining a relationship between the components of the elasticity tensor, the components of the texture tensor and the volume fraction of the porous medium, the author notes that resulting the elasticity tensor does not yield all possible types of symmetry of the porous material, being restricted to orthotropy and its particular cases, such as the isotropic and transverse isotropy. The elasticity tensor obtained by Cowin (1985) does not describe the local behavior of porous media, and depends explicitly on the fabric tensor components, which represent a non local measure. This dissertation aims to study and analyze the model proposed by Cowin (1985). A formulation for the response function of linear elastic porous materials under infinitesimal deformation that describes the local behavior of the porous medium is also proposed.

Although there are now many theories describing empirical relationships between strength properties of bone and various explanatory variables, the need for improved non-invasive diagnostic techniques to assess bone fragility is of core importance in clinical problems such as osteoporosis. The aim of this thesis was to develop non-invasive radiological methods to assess trabecular bone architecture. Measures of structural anisotropy and bone structure from X-ray or radiological projections have been developed. The first measure, the projected mean intercept length (PMIL), allows extraction of the total bone surface (BS/TV) and the mean intercept length (MIL) from projections of trabecular structure. The second measure, the line projection deviation (LPD), is a technique that quantifies the preferential alignment of trabecular bone from projections of the trabecular structure. Hence, in combination, the PMIL and LPD allow non-invasive extraction of BS/TV and more detailed preferential alignment from projections of the trabecular structure. In this thesis the PMIL and LPD are introduced and their properties explored. The PMIL and LPD are used to examine the anisotropy and architectural properties of a number of human vertebral body trabecular bone samples. When used in combination with clinical densitometry, these measures improve explanation of the variance in strength, elastic modulus and toughness of vertebral body trabecular bone samples by up to 40% when compared to densitometric values alone. While µCT can provide the information needed to access trabecular architecture, it cannot be used in clinical settings since its high radiation dose makes it only applicable to small objects ex-vivo. At present, clinically available CT does not provide sufficient resolution to resolve trabecular structures. Thus, the methods described in this thesis will allow estimates of structural parameters from plain X-rays, providing for the first time, the possibility of clinical use of such estimates. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1311218 / Thesis (Ph.D.) -- School of Medical Sciences, 2008

Weak and osteoporotic bones are an increasing cause of mortality and painful physical impairment among the elderly, especially in the Western world. Bone mineral density (BMD, g/cm2) accrual during childhood and adolescence is thought to influence an individual’s risk of osteoporosis and the related fractures. A main aim of this thesis is to investigate the effects that various types of weight-bearing physical activity have on bone accretion in young males during their active sports careers and to study the effects that detraining has on BMD. The results suggest that bone is sensitive to loading after puberty in males, and important gains in BMD stemming from physical activity were observed during the 12-year follow-up period (papers I-III). These gains seem to be site-specific and related to the type and amount of physical activity in which individuals participate (papers I-III). For example, badminton, a sport that is characterized by jumps and rapid versatile moments in multiple directions was associated with greater gains in BMD than ice hockey was. In addition, our results indicate that with reduced training, exercise-induced bone benefits decline, predominantly at trabecular sites (paper II). In contrast, high bone density attained from previous physical loading was partially preserved at cortical bone sites after about eight years of reduced activity (papers I-II). In study IV, the associations between self-perceived health, BMD, and other lifestyle factors were studied in a well-defined group of women and men of varying ages. We found that self-perceived health was related to several lifestyle factors, such as physical activity, which were also related to BMD at the femoral neck. In summary, BMD in young males seem to be especially sensitive to activities associated with supposed high strains in unusual directions at specific bone sites. A high bone density stemming from previous weight-bearing physical activity is largely lost at trabecular bone sites with reduced physical activity levels. Finally, self-perceived health seems to be associated with several lifestyle factors that are also associated with BMD at the femoral neck.

Objective: Injuries to the marrow cavity result in rapid bone formation followed by regeneration of the marrow. It is not known whether this process is affected by age, although the quality of marrow is markedly different in young and old animals. To test if marrow restoration differs with age, we used the rat tibial bone marrow ablation model, which has been used to examine calcification, osteointegration of metal implants, and remodeling of bone graft substitutes. Methods: Marrow was ablated in the left tibia of seven rats (rNu/rNu) per time point. At 0,7,14,21,28,35 and 42 days post-surgery, treated tibias and contralateral tibias were harvested and fixed in buffered formalin. Both tibias were scanned using microCT and trabecular and cortical BVF/TV calculated. Mid-sagittal sections of decalcified bones were stained with H&E and BVF/TV calculated. Results: MicroCT analysis of 1-month animals showed increased bone formation on day-7 and on day-21 the marrow was restored. Increased bone was seen in 3-month animals on day-7 and day-14, but it was significantly less than in 1-month rats. By day-21, trabecular bone was reduced by 50%. 10-month animals had less trabecular bone at day-7 and 14, but bone remained in the medullary canal through day-1. Histomorphometry indicated that bone formation peaked at day-7 in 1-month rats with remodeling underway by day-14. Bone formation in 3-month rats also peaked at day-7, but restoration occurred by day-21. However, in 10-month rats, peak bone occurred on day-14, with remodeling on day-28. Conclusions: Aged animals produced less primary bone than younger animals and remodeling was initiated later. Differences in micro-CT and histomorphometric analyses may reflect a reduction in calcification of the osteoid in the 10-month old animals. (Supported by Boston Scientific, Inc.)

A osteoporose, doença caracterizada pela redução da massa óssea e deterioração da microestrutura óssea, atinge a população idosa e afeta centenas de milhões de pessoas em todo mundo. Por manifestar-se sem causar sintoma visível, o diagnóstico da doença ocorre, na maioria dos casos após lesão ou fratura do osso. Na tentativa de detectar os sinais iniciais da doença, utilizam-se diferentes métodos de avaliação da qualidade óssea baseados na medida da densidade e da arquitetura óssea. Atualmente existe um grande interesse em estabelecer uma correlação entre as medidas de qualidade óssea com as propriedades mecânicas de resistência do osso. Uma estratégia para caracterizar o comportamento mecânico do osso consiste em obter as propriedades da macroestrutura óssea a partir das propriedades da sua microestrutura. Cowin (1985) propõe um modelo mecânico para materiais porosos elástico-lineares supondo que a função resposta mecânica do meio poroso elástico sob deformações infinitesimais é uma função isotrópica do tensor deformação infinitesimal, da fração volumétrica e do tensor textura que caracteriza a simetria do arranjo geométrico do meio poroso. Ao obter uma relação entre as componentes do tensor de elasticidade, as componentes do tensor textura e a fração volumétrica do meio poroso, o autor observa que o tensor de elasticidade obtido não fornece todos os tipos possíveis de simetria do material poroso, restringindo-se apenas à ortotropia e seus casos particulares, tais como a isotropia e a isotropia transversal. O tensor de elasticidade obtido por Cowin (1985) não descreve o comportamento local do meio poroso, pois depende explicitamente das componentes do tensor textura, o qual representa uma medida não local. Esta dissertação tem por objetivo estudar e analisar o modelo proposto por Cowin (1985). Propõe-se neste trabalho uma formulação para a função resposta de materiais porosos elástico-lineares para deformações infinitesimais que descreva o comportamento local do meio poroso. / Osteoporosis, a disease characterized by the reduction of bone mass and deterioration of bone microstructure deterioration, affects the elderly population and hundreds of millions of people worldwide. As a silent disease, its diagnosis occurs, in most cases, after injury, or, bone fracture. In an attempt to detect early signs of the disease, different methods of diagnostic imaging to obtain measures of density and bone architecture are used. Currently, there is great interest in establishing a correlation between the measurements of bone quality with the mechanical properties of bone strength. One strategy to characterize the mechanical behavior of bones is to obtain the properties of its macrostructure from the properties of its microstructure. Cowin (1985) proposes a mechanical model for porous materials by assuming that the mechanical response function of the material under infinitesimal deformation is a function of the infinitesimal deformation tensor, the volume fraction, and the texture tensor that characterizes the symmetry of the geometrical arrangement of the porous medium. By obtaining a relationship between the components of the elasticity tensor, the components of the texture tensor and the volume fraction of the porous medium, the author notes that resulting the elasticity tensor does not yield all possible types of symmetry of the porous material, being restricted to orthotropy and its particular cases, such as the isotropic and transverse isotropy. The elasticity tensor obtained by Cowin (1985) does not describe the local behavior of porous media, and depends explicitly on the fabric tensor components, which represent a non local measure. This dissertation aims to study and analyze the model proposed by Cowin (1985). A formulation for the response function of linear elastic porous materials under infinitesimal deformation that describes the local behavior of the porous medium is also proposed.