Análise biomecânica das fraturas do fémur e avaliação do melhor implante

As fraturas ósseas na região diafisária do fémur são lesões complexas das quais resultam, habitualmente, períodos extensos de hospitalização e de reabilitação. O recurso a hastes intramedulares bloqueadas, no que diz respeito à fixação intramedular, é um dos tratamentos possíveis deste tipo de fraturas e tem sido objeto de vários trabalhos de investigação desde o seu aparecimento. Neste sentido, o presente trabalho focou-se no desenvolvimento de uma metodologia de análise computacional de diferentes tipos de fraturas diafisárias do fémur, seguindo o tipo de tratamento utilizado no hospital Nossa Senhora das Dores - Brasil. Foi gerado um biomodelo e um modelo simplificado do conjunto osso-implante-parafusos seguida de uma análise por elementos finitos. Os resultados obtidos indicam que a introdução das hastes intramedulares em aço inoxidável ou em titânio no fémur diminuem as tensões ao longo do osso, promovendo uma maior estabilidade. O estudo efetuado permitiu identificar a zona medial do fémur como a zona crítica no que diz respeito às tensões envolvidas. Na análise comparativa das tensões com diferentes materiais, o modelo com a haste em titânio apresentou um desempenho mais homogéneo do que o modelo em aço inoxidável. O modelo simplificado apresentou resultados compatíveis com o biomodelo. Este facto possibilita que o modelo simplificado se torne uma ferramenta vantajosa na análise biomecânica das fraturas diafisárias do fémur, uma vez que não há recurso a imagens médicas.Bone fractures in the femoral diaphysis are complex lesions that usually result in extended periods of hospitalization and rehabilitation. The use of locked intramedullary nails in intramedullary fixation is one of the possible treatments of this type of fracture and has been the subject of several researches since its appearance. The present work focused on developing a methodology for computational analysis of different types of femoral diaphysis fractures, according the type of treatment at Nossa Senhora das Dores – Brazil hospital. It was created a biomodel and a simplified model of the boneimplant screws followed by a finite element analysis. The results indicate that the introduction of intramedullary nails of stainless steel or titanium into the femur reduce the stresses along the bone, providing a greater stability. The study identifies the femur medial zone as the critical region related to the stresses that are involved. The comparative analysis of strains with different materials suggests that the model in titanium was more homogenous than the model in stainless steel. The simplified model showed consistent results with the biomodel. This fact allows that the simplified model becomes an advantageous tool in biomechanical analysis of the femoral diaphysis fractures because the analysis may be unprovided with medical images

Temperature assessment in the drilling of composite materials and ex-vivo porcine bones

This study presents different experimental methodologies for analysis and temperature evaluation during the drilling process of composite materials and ex-vivo porcine bones. In the experimental methodologies were evaluated the influence of different parameters on the bone temperature rise. The combinations of different parameters produced temperatures far below the critical values. It was concluded that drill temperature decreases when the feed-rate is higher and, independently, increases with the increasing of hole depth. The influence of drill speed is not clear. In the composite materials the temperature decreases in the drill bit when the drill speed is higher, and in ex-vivo porcine bones happens the opposite. The animal models recorded lower temperature values than composite materials.The author of this paper acknowledges the support of the Project "Biomechanics: Contributions to the healthcare" co-financed by the Regional Operational Programme of North (ON.2 -The New North), the National Strategic Reference Framework (NSRF), through the European Development Fund (ERDF) and also to the project UID/EM/50022/2013 of LAETA financed by FCT

Measure and comparison of speech pause duration in subjects with disfluency speech

This work has lhe goal of comparing the pause duration in lhe disfluency speech and nonnal speech. Disfluency and normal sponlaneous spccch was rccordcd in a contcxl were the subjcels had to deseribe a scenc fram each othcr. 1l1C pause determin;Jtion algorithm was dcvelopcd. The automatic pause determinations allowed lhe measure of percenlage of silence along the record of several minutcs of spcech. As expecled lhese paramelers is ralher diffcrent in subjecIs with and wi thout disfluency spcech. but it do nol scems that it is proponional la lhe sevcrity of lhe disfluency

Automatic determination of pauses in speech for classification of stuttering disorder

An algorithm to automatically identify segments of silence or speech is presented. The algorithm was developed to measure the silence periods in spontaneous and read speech. These silence periods are one of the parameters used to know the degree of severity of stuttered speech. For this purpose the three longer disfluent events (pauses or other disfluent events) and also the percentage of silence are useful. The algorithm is based on the evaluation of the energy and the zero crossing rate of the signal compared to the threshold values previously determined in silence. One experiment with eight subjects is described using the Stuttering Severity Instrument for Children and Adults – SSI and the percentage of silence in speech. It was concluded that the percentage of silence is good enough to separate stuttered from the normal speech but alone is not capable of measuring the degree of severity of the stuttered speech.info:eu-repo/semantics/publishedVersio

Mechanomodulatory biomaterials prospects in scar prevention and treatment

Scarring is a major clinical issue that affects a considerable number of patients. The associated problems go beyond the loss of skin functionality, as scars bring aesthetic, psychological, and social difficulties. Therefore, new strategies are required to improve the process of healing and minimize scar formation. Research has highlighted the important role of mechanical forces in the process of skin tissue repair and scar formation, in addition to the chemical signalling. A more complete understanding of how engi- neered biomaterials can modulate these mechanical stimuli and modify the mechanotransduction signals in the wound microenvironment is expected to enable scar tissue reduction. The present review aims to provide an overview of our current understanding of skin biomechanics and mechanobiology underlying wound healing and scar formation, with an emphasis on the development of novel mechanomodulatory wound dressings with the capacity to offload mechanical tension in the wound environment. Further- more, a broad overview of current challenges and future perspectives of promising mechanomodulatory biomaterials for this application are provided.The authors would like to acknowledge Portuguese Foun dation for Science and Technology (FCT) for funding the research project Dressing4Scars M-ERA-NET2/0013/2016, and LP da Silva (2020.01541.CEECIND/CP1600/CT0024), and to Norte-01-0145-FEDER-02219015 (MT Cerqueira)

Análise térmica durante o processo de furação do osso cortical e trabecular

Procedimentos cirúrgicos que envolvem o corte do tecido ósseo são uma prática cada vez mais frequente na medicina, sendo de extrema importância conhecer o comportamento deste tecido durante e após a cirurgia. A perda de tecido ósseo devido à produção excessiva de calor, durante os processos de furação óssea, é um dos problemas mais comuns e estudados na literatura. Diversos autores revelam que o aumento da temperatura durante a furação está diretamente relacionado com os parâmetros de corte escolhidos, nomeadamente a velocidade de corte, a velocidade de avanço, a força aplicada, a profundidade do corte, a utilização ou não de um sistema de refrigeração, a geometria da ferramenta de corte, e também o tipo de material da broca e de osso

Thermal analysis in the drilling of solid rigid foam materials and ex-vivo bovine bones

Bone is a dynamic, highly vascularized tissue with a unique capacity to heal and regenerate without scarring. However, drilling remains a concern in several clinical procedures due to thermal damage of the bone and surrounding tissue. The success of this surgeries is dependent of many factors and also in temperature generation during the drilling bone. When an excessive heat is produced during the drilling, thermal necrosis can occur and the bone suffers injuries. Studies have shown that the increased temperature is directly related with the drilling parameters, particularly, the drill speed, feed-rate, applied force, the depth of cut, the geometry of the drill bit, the use or not of a cooling system and also the type of bone

Determinação dos parâmetros ótimos na furação do tecido ósseo com recurso ao método de Taguchi

Durante o processo de furação, muitas vezes utilizado para a fixação de implantes, é gerado um aumento de temperatura na região do osso que se encontra sob o efeito de um processo de maquinagem. Se o aumento de temperatura for demasiado elevado pode ocorrer a necrose de tecido ósseo com a consequente diminuição da eficiência do sistema de fixação. Neste estudo foram utilizados fémures de bovino com o objetivo de estudar o efeito da velocidade de rotação e diâmetro da broca no aumento de temperatura durante o processo de furação. Os parâmetros definidos para a realização dos ensaios experimentais foram obtidos com base no método de Taguchi

Avaliação biomecânica das fraturas diafisárias do fémur

As fraturas diafisárias do fémur são lesões complexas resultando em períodos extensos de hospitalização e de reabilitação. O recurso a hastes intramedulares bloqueadas, no que diz respeito à fixação intramedular, é um dos tratamentos possíveis deste tipo de fraturas e tem sido objeto de vários trabalhos de investigação. O presente trabalho tem como objetivo principal apresentar uma metodologia para a avaliação biomecânica de diferentes tipos de fraturas diafisárias do fémur, seguindo um tipo de tratamento utilizado no hospital Nossa Senhora das Dores no Brasil