Criação de zonas de alta permeabilidade em fraturas: modelagem numérica do Lajedo de Soledade, Formação Jandaíra, Bacia Potiguar

The fracturing in carbonate rocks has been attracting increasingly attention due to new oil discoveries in carbonate reservoirs. This study investigates how the fractures (faults and joints) behave when subjected to different stress fields and how their behavior may be associated with the generation of karst and consequently to increased secondary porosity in these rocks. In this study I used satellite imagery and unmanned aerial vehicle UAV images and field data to identify and map faults and joints in a carbonate outcrop, which I consider a good analogue of carbonate reservoir. The outcrop comprises rocks of the Jandaíra Formation, Potiguar Basin. Field data were modeled using the TECTOS software, which uses finite element analysis for 2D fracture modeling. I identified three sets of fractures were identified: NS, EW and NW-SE. They correspond to faults that reactivate joint sets. The Ratio of Failure by Stress (RFS) represents stress concentration and how close the rock is to failure and reach the Mohr-Coulomb envelopment. The results indicate that the tectonic stresses are concentrated in preferred structural zones, which are ideal places for carbonate dissolution. Dissolution was observed along sedimentary bedding and fractures throughout the outcrop. However, I observed that the highest values of RFS occur in fracture intersections and terminations. These are site of karst concentration. I finally suggest that there is a relationship between stress concentration and location of karst dissolution in carbonate rocks.

Bone morphology of the femur and tibia captured by statistical shape modelling predicts rapid bone loss in acute spinal cord injury patients

We would like to thank the study participants and the clinical and research staff at the Queen Elizabeth National Spinal Injury Unit, as without them this study would not have been possible. We are grateful for the funding received from Glasgow Research Partnership in Engineering for the employment of SC during data collection for this study. We would like to thank the Royal Society of Edinburgh's Scottish Crucible scheme for providing the opportunity for this collaboration to occur. We are also indebted to Maria Dumitrascuta for her time and effort in producing inter-repeatability results for the shape models.

Bone morphology of the femur and tibia captured by statistical shape modelling predicts rapid bone loss in acute spinal cord injury patients

We would like to thank the study participants and the clinical and research staff at the Queen Elizabeth National Spinal Injury Unit, as without them this study would not have been possible. We are grateful for the funding received from Glasgow Research Partnership in Engineering for the employment of SC during data collection for this study. We would like to thank the Royal Society of Edinburgh's Scottish Crucible scheme for providing the opportunity for this collaboration to occur. We are also indebted to Maria Dumitrascuta for her time and effort in producing inter-repeatability results for the shape models.

Postoperative analgesic effect, of preoperatively administered dexamethasone, after operative fixation of fractured neck of femur: randomised, double blinded controlled study.

Background: Fractured neck of femur is a common cause of hospital admission in the elderly and usually requires operative fixation. In a variety of clinical settings, preoperative glucocorticoid administration has improved analgesia and decreased opioid consumption. Our objective was to define the postoperative analgesic efficacy of single dose of dexamethasone administered preoperatively in patients undergoing operative fixation of fractured neck of femur. Methods: Institutional ethical approval was granted and written informed consent was obtained from each patient. Patients awaiting for surgery at Cork University Hospital were recruited between July 2009 and August 2012. Participating patients, scheduled for surgery were randomly allocated to one of two groups (Dexamethasone or Placebo). Patients in the dexamethasone group received a single dose of intravenous dexamethasone 0.1 mg kg -1 immediately preoperatively. Patients in the placebo group received the same volume of normal saline. Patients underwent operative fixation of fractured neck of femur using standardised spinal anaesthesia and surgical techniques. The primary outcome was pain scores at rest 6 h after the surgery. Results: Thirty seven patients were recruited and data from thirty patients were analysed. The groups were similar in terms of patient characteristics. Pain scores at rest 6 h after the surgery (the principal outcome) were lesser in the dexamethasone group compared with the placebo group [0.8(1.3) vs. 3.9(2.9), mean(SD) p = 0.0004]. Cumulative morphine consumption 24 h after the surgery was also lesser in the dexamethasone group [7.7(8.3) vs. 15.1(9.4), mean(SD) mg, p = 0.04]. Conclusions: A single dose of intravenous dexamethasone 0.1 mg kg -1 administered before operative fixation of fractured neck of femur improve significantly the early postoperative analgesia. Trial registration: ClinicalTrials.gov identifier: NCT01550146, date of registration: 07/03/2012

Avaliação histomorfométrica do efeito do ultrasom pulsado nas falhas ósseas provocadas em fêmures de rato: estudo experimental

SILVA, J. S. P. Avaliação histomorfométrica do efeito do ultrasom pulsado nas falhas ósseas provocadas em fêmures de rato: estudo experimental . 2000. 85 f. Dissertação (Mestrado) – Faculdade de Medicina, Universidade de São Paulo. São Paulo, 2000.

Cirurgia de fraturas ósseas na osteoporose: Fraturas da coluna vertebral

As fraturas que ocorrem no osso osteoporótico são por definição estrita fraturas patológicas. Podem estar relacionadas com quedas da própria altura ou de traumatismos de baixa energia cinética e envolvem habitualmente a anca, o punho, a coluna vertebral e o ombro. As fraturas osteoporóticas a que se associa a sarcopenia, representam um sério problema de saúde pública em todo o mundo, com uma proporção epidémica e um impacto devastador na morbilidade e mortalidade dos pacientes, assim como nos custos socioeconómicos. Apesar dos avanços registados na prevenção e no tratamento farmacológico da osteoporose bem como no tratamento cirúrgico das fraturas ósseas, continuam a ser desenvolvidos novos biomateriais metálicos e substitutos sintéticos do osso com a intenção de se conseguir alcançar melhores resultados clínicos. Dentro deste contexto incluem-se os cimentos hidráulicos, os parafusos expansivos, os parafusos dinâmicos, as malhas metálicas de titânio, as placas bloqueadas, entre outros, em conjugação com técnicas minimamente invasivas e com diferentes estratégias cirúrgicas. O objetivo central deste trabalho assenta nas modalidades cirúrgicas mais usadas para o tratamento das fraturas em osso osteoporótico, com especial destaque para as fraturas da coluna vertebral.

Avaliação histomorfométrica do efeito do ultrasom pulsado nas falhas ósseas provocadas em fêmures de rato: estudo experimental

SILVA, J. S. P. Avaliação histomorfométrica do efeito do ultrasom pulsado nas falhas ósseas provocadas em fêmures de rato: estudo experimental . 2000. 85 f. Dissertação (Mestrado) – Faculdade de Medicina, Universidade de São Paulo. São Paulo, 2000.

Fraturas dentárias

Uma lesão traumática é, a seguir à cárie dentária, um dos problemas mais comuns da saúde oral. O traumatismo dentário consiste numa agressão que afeta os dentes ou os tecidos de suporte, podendo levar ao rompimento do ligamento periodontal, fratura dentária, fratura óssea ou alterações pulpares. Este problema causa desconforto físico, emocional e comprometimento estético. Quando os traumatismos afetam os tecidos duros ou polpa denominam-se de fraturas dentárias. Estas podem ser divididas em fraturas coronárias de esmalte; fraturas coronárias de esmalte e dentina sem exposição pulpar; fraturas coronárias de esmalte e dentina com exposição pulpar; fraturas corono-radiculares de esmalte, dentina e cemento sem exposição pulpar; fraturas corono-radiculares com exposição pulpar e fratura radicular envolvendo cemento, dentina e polpa. O objetivo deste trabalho monográfico foi fazer uma revisão bibliográfica de estudos científicos sobre fraturas dentárias. Assim, serão abordados os diversos tipos de fraturas dentárias, as suas etiologias, prevalências e fatores associados, também definir planos de tratamento, técnicas de restauração direta de fraturas coronárias e possíveis medidas de prevenção. A pesquisa bibliográfica para esta revisão foi realizada em bases eletrónicas de referência como Pubmed, Scielo, selecionando artigos entre os anos 2006 e 2016. Foram também utilizados como elementos de pesquisa o site Dental Trauma Guide (DTG), o site International Association of Dental Traumatology (IADT), livros da especialidade existentes na Biblioteca da Universidade Fernando Pessoa que embora com datas de publicação mais antigas (2001) foram imprescindíveis para o desenvolvimento da monografia. A pesquisa foi realizada em duas línguas, português e inglês. Como conclusão pode-se dizer que nos dias de hoje, o médico dentista tem muitas opções de tratamento de dentes fraturados. Para restaurar a fratura o médico pode optar por colar o fragmento, restaurar usando uma matriz guia ou restaurar à mão livre. A escolha da técnica deve ser estudada de acordo com cada paciente e suas expectativas.

Cirurgia de fraturas ósseas na osteoporose: Fraturas da coluna vertebral

As fraturas que ocorrem no osso osteoporótico são por definição estrita fraturas patológicas. Podem estar relacionadas com quedas da própria altura ou de traumatismos de baixa energia cinética e envolvem habitualmente a anca, o punho, a coluna vertebral e o ombro. As fraturas osteoporóticas a que se associa a sarcopenia, representam um sério problema de saúde pública em todo o mundo, com uma proporção epidémica e um impacto devastador na morbilidade e mortalidade dos pacientes, assim como nos custos socioeconómicos. Apesar dos avanços registados na prevenção e no tratamento farmacológico da osteoporose bem como no tratamento cirúrgico das fraturas ósseas, continuam a ser desenvolvidos novos biomateriais metálicos e substitutos sintéticos do osso com a intenção de se conseguir alcançar melhores resultados clínicos. Dentro deste contexto incluem-se os cimentos hidráulicos, os parafusos expansivos, os parafusos dinâmicos, as malhas metálicas de titânio, as placas bloqueadas, entre outros, em conjugação com técnicas minimamente invasivas e com diferentes estratégias cirúrgicas. O objetivo central deste trabalho assenta nas modalidades cirúrgicas mais usadas para o tratamento das fraturas em osso osteoporótico, com especial destaque para as fraturas da coluna vertebral.

Numerical investigations on the strain-adaptive bone remodelling in the periprosthetic femur: Influence of the boundary conditions

Background: There are several numerical investigations on bone remodelling after total hip arthroplasty (THA) on the basis of the finite element analysis (FEA). For such computations certain boundary conditions have to be defined. The authors chose a maximum of three static load situations, usually taken from the gait cycle because this is the most frequent dynamic activity of a patient after THA. Materials and methods: The numerical study presented here investigates whether it is useful to consider only one static load situation of the gait cycle in the FE calculation of the bone remodelling. For this purpose, 5 different loading cases were examined in order to determine their influence on the change in the physiological load distribution within the femur and on the resulting strain-adaptive bone remodelling. First, four different static loading cases at 25%, 45%, 65% and 85% of the gait cycle, respectively, and then the whole gait cycle in a loading regime were examined in order to regard all the different loadings of the cycle in the simulation. Results: The computed evolution of the apparent bone density (ABD) and the calculated mass losses in the periprosthetic femur show that the simulation results are highly dependent on the chosen boundary conditions. Conclusion: These numerical investigations prove that a static load situation is insufficient for representing the whole gait cycle. This causes severe deviations in the FE calculation of the bone remodelling. However, accompanying clinical examinations are necessary to calibrate the bone adaptation law and thus to validate the FE calculations.

Nova técnica para obtenção de fraturas com altíssima condutividade em poços de petróleo

Increase hydrocarbons production is the main goal of the oilwell industry worldwide. Hydraulic fracturing is often applied to achieve this goal due to a combination of attractive aspects including easiness and low operational costs associated with fast and highly economical response. Conventional fracturing usually involves high-flowing high-pressure pumping of a viscous fluid responsible for opening the fracture in the hydrocarbon producing rock. The thickness of the fracture should be enough to assure the penetration of the particles of a solid proppant into the rock. The proppant is driven into the target formation by a carrier fluid. After pumping, all fluids are filtered through the faces of the fracture and penetrate the rock. The proppant remains in the fracture holding it open and assuring high hydraulic conductivity. The present study proposes a different approach for hydraulic fracturing. Fractures with infinity conductivity are formed and used to further improve the production of highly permeable formations as well as to produce long fractures in naturally fractured formations. Naturally open fractures with infinite conductivity are usually encountered. They can be observed in rock outcrops and core plugs, or noticed by the total loss of circulation during drilling (even with low density fluids), image profiles, pumping tests (Mini-Frac and Mini Fall Off), and injection tests below fracturing pressure, whose flow is higher than expected for radial Darcian ones. Naturally occurring fractures are kept open by randomly shaped and placed supporting points, able to hold the faces of the fracture separate even under typical closing pressures. The approach presented herein generates infinite conductivity canal held open by artificially created parallel supporting areas positioned both horizontally and vertically. The size of these areas is designed to hold the permeable zones open supported by the impermeable areas. The England & Green equation was used to theoretically prove that the fracture can be held open by such artificially created set of horizontal parallel supporting areas. To assess the benefits of fractures characterized by infinite conductivity, an overall comparison with finite conductivity fractures was carried out using a series of parameters including fracture pressure loss and dimensionless conductivity as a function of flow production, FOI folds of increase, flow production and cumulative production as a function of time, and finally plots of net present value and productivity index

The use of expandable megaprostheses for reconstruction of the distal femur in pediatric patients after bone tumor resection

Expandable prostheses are becoming increasingly popular in the reconstruction of children with bone sarcomas of the lower limb. Since the introduction of effective chemotherapy in the treatment of these pathologies, in the 70s, there has been need for new limb salvage techniques. In children, limb salvage of the lower limbs is particularly challenging, not in the last place, because of the loss of growth potential. Therefore, expandable prostheses have been developed. However, the first experiences with these implants were not very successful. High complication rates and unpredictable outcomes raised major concerns on this innovative type of reconstruction. The rarity of the indication is one of the main reasons why there has been a relatively slow learning curve and implant development regarding this type of prosthesis. This PhD thesis, gives an overview of the introduction, the development, the current standards, and the future perspectives of expandable prostheses for the reconstruction of the distal femur in children.

Fatores de risco para fraturas em idosos

O material é componente do Curso de Especialização em Saúde da Pessoa Idosa da UNA-SUS/UFMA (Unidade 02, do módulo 07). Trata-se de um recurso educacional interativo que apresenta os fatores de risco para fraturas em idosos, como fratura prévia, déficit visual, menopausa, dentre outros.