Comportamiento del polietileno en un simulador de cadera

Se presentan los resultados del comportamiento friccional de cinco diferentes combinaciones de cabezas protésicas femorales y polietileno acetabular, investigadas en un simulador de cadera. Las cabezas femorales de aleaciones de Cr-Co-Mo, Cr-Co-Mo con implantación iónica y de cerámica de zirconia, se articularon con cotilos de polietileno de ultra-alto-peso molecular y se sometieron a tres millones de ciclos de marcha cada uno, utilizando un simulador de cadera de cinco estaciones. El desgaste de los cotilos protésicos, evaluado por mediciones gravimétricas demostró que cuando el espesor de polietileno era de 10,9 mm el desgaste producido por cabezas de Cr-Co-Mo de 28 mm era de 0,14 mm/año y de 0,09 mm/año si la cabeza utilizada era de 28 mm de aleación de Cr-Co- Mo con implantación iónica. Cuando el espesor del acetábulo era de 7 mm el desgaste ocasionado por cabezas de cerámica de zirconia de 28 mm fue de 0,04 mm/año; sin embargo si tenía espesor 10,9 mm y las cabezas de cerámica de zirconia eran de 28 y 32 mm, no aparecía desgaste alguno. Estos resultados indican que el diámetro de la cabeza de cerámica de 28 y 32 mm, parece no tener importancia alguna, pero sí la tiene el que el espesor del acetábulo protésico sea menor de 10 mm.Ultra high molecular weight polyethylene (UHMWPE) metal backed acetabular cups were articulated against Cr-Co-Mo alloy, ion implanted Cr-Co-Mo and zirconia ceramic femoral heads in a five station hip joint simulator, running three tests of three millions walking cycles with each one of the five different head-cup combinations. The wear rate of the acetabular cups was measured gravimetrically. When the thickness of the cup was 10.9 mm, the mean wear rate against 28 mm diameter Cr-Co-Mo femoral heads was 0.14 mm/year, and 0.09 mm/year 'when the cup was articulated against 28 mm ion implanted Cr-Co-Mo femoral heads. When the thickness of the cup was 7 mm the mean wear rate was 0.04 mm/year against 28 mm zirconia heads. The results indicate that significant reduction in the wear of the UHMWPE cup can be achieved when zirconia femoral head is used and that the diameter of the zirconia femoral head, 28 vs 32 mm, seems unimportant as wear factor. A cup thickness below 10 mm may result disadvantageous

Numerical modelling of hip fracture patterns in human femur

[EN] Background and Objective: Hip fracture morphology is an important factor determining the ulterior surgical repair and treatment, because of the dependence of the treatment on fracture morphology. Although numerical modelling can be a valuable tool for fracture prediction, the simulation of femur fracture is not simple due to the complexity of bone architecture and the numerical techniques required for simulation of crack propagation. Numerical models assuming homogeneous fracture mechanical properties commonly fail in the prediction of fracture patterns. This paper focuses on the prediction of femur fracture based on the development of a finite element model able to simulate the generation of long crack paths. Methods: The finite element model developed in this work demonstrates the capability of predicting fracture patterns under stance loading configuration, allowing the distinction between the main fracture paths: intracapsular and extracapsular fractures. It is worth noting the prediction of different fracture patterns for the same loading conditions, as observed during experimental tests. Results and conclusions: The internal distribution of bone mineral density and femur geometry strongly influences the femur fracture morphology and fracture load. Experimental fracture paths have been analysed by means of micro-computed tomography allowing the comparison of predicted and experimental crack surfaces, confirming the good accuracy of the numerical model.The authors are indebted to University Complutense of Madrid and to the radiological team of the Hospital Universitario Infanta Leonor for supporting the experimental work on human bones included in this paper. The micro-CTs were performed in the Micro-Computed Tomography laboratory at CENIEH facilities with the collaboration of CENIEH staff. The authors gratefully acknowledge the funding support received from the Spanish Ministry of Economy and Competitiveness and the FEDER operation program for funding the projects DPI2013-46641-R, DPI2017-89197-C2-1-R, DPI2017-89197-C2-2-R, RTC-2015-3887-8 and the Generalitat Valenciana through theproject Prometeo/2016/007. The authors also acknowledge the funding support received from the Fundacion Espanola de Investigacion Osea y del Metabolismo Mineral through the 2018 research fellowship program.Marco, M.; Giner Maravilla, E.; Caeiro-Rey, JR.; Miguélez, MH.; Larrainzar-Garijo, R. (2019). Numerical modelling of hip fracture patterns in human femur. Computer Methods and Programs in Biomedicine. 173:67-75. https://doi.org/10.1016/j.cmpb.2019.03.010S677517

Allergenic Airborne Pollen in Portugal 2002-2004

Os calendários polínicos constituem instrumentos fundamentais para a orientação clínica de doentes alérgicos. Em Portugal, a sua elaboração de forma sistematizada teve início em 2002. Para tal foram colocados polinómetros volumétricos Burkard em cinco cidades do país: Porto, Coimbra, Lisboa, Évora e Portimão. O registo das contagens foi efectuado por método estandardizado. As contagens polínicas diárias expressam a concentração média por m3. Estas contagens foram objecto de análise descritiva e comparativa. O período de incidência polínica máxima decorre entre Março e Julho, sendo o pólen de Poaceae e de ervas silvestres os mais frequentemente identificados. Em Janeiro, Fevereiro e Dezembro existem níveis elevados de pólen de árvores em todo o território nacional. O Sul do país apresenta indicadores de polinização mais intensa

Adenovirus Infection in a Kidney–Pancreatic Transplant Recipient: Case Report

Adenovirus infection in transplant recipients may present from asymptomatic viremia to multisystemic involvement. Most frequently, it occurs in the first year after a kidney transplant, and it is secondary to the reactivation of latent disease. However, primary infection may occur, and disseminated disease is more common when related to primary infection. Kidney involvement may be confirmed by biopsy, although diagnosis may be presumptive. Reduction of immunosuppression and supportive care are important components of therapy. CASE DESCRIPTION: A 41-year-old female renal-pancreatic recipient 12 years before with chronic renal graft dysfunction and a functional pancreatic graft had a history of cytomegalovirus and polyoma virus infection 2 years after transplantation. She was taking tacrolimus, mycophenolate mofetil, and prednisolone. The patient was admitted after persistent uncharacteristic diarrhea 3 weeks before hospitalization without any relevant epidemiologic context. She was dehydrated, and the lab results showed worsened kidney function and leucocytosis. The viral culture revealed adenovirus. Vigorous hydration was implemented, and the mycophenolate mofetil dose was reduced. The patient was discharged, and renal function returned to previous values. DISCUSSION AND CONCLUSION: Adenovirus infection has a wide clinical presentation, and multisystemic involvement may occur in transplant recipients. Supportive care is paramount. The clinical features and viral culture confirm the diagnosis, although tissue samples and quantitative polymerase chain reaction may be required in more severe cases.info:eu-repo/semantics/publishedVersio

Determinação da Carga Alergénica (Ole e1) Presente no Ar Atmosférico na Região de Évora: Correlação com o conteúdo polínico de Olea

Introdução: Em Portugal, o pólen da oliveira (Olea europaea) constitui uma das fontes mais relevantes de aero-alergénios, sendo uma causa frequente de polinose na região Mediterrânica, onde o Ole e 1 é um alergeno major. Apesar de se julgar apenas associado aos grãos de pólen, desconhece-se a variabilidade inter-anual da carga alergénica do pólen e ainda existe alguma controvérsia sobre a forma como este aeroalergeno se distribui no ar atmosférico. Objectivo: Este trabalho teve como objectivos: i) determinar a fracção dos bioaerossóis mais rica em Ole e 1; ii) avaliar a correlação dos conteúdos diários de pólen e aeroalergeno no ar atmosférico; iii) avaliar variação anual da carga alergénica do pólen. Métodos: Os aeroalergenos foram captados utilizando um colector de impacto CHEMVOL equipado com dois filtros com capacidade para reter partículas de diferentes dimensões: PM>10µm e 10µm>PM>2,5µm. Após 24h os filtros foram retirados, a fracção proteica foi extraída e os alergenos quantificados por ELISA. Simultaneamente o pólen foi monitorizado pela tecnologia padrão utilizando um colector volumétrico Burkard 7-Day Recording Volumetric Spore Trap. Os colectores foram ambos colocados numa mesma plataforma a 17m de altura, e a ≈3-4m um do outro. Resultados: Entre 2009 e 2011, registou-se uma variação inter-anual quer do perfil quer da duração da época polínica (39, 47 e 45 dias, respectivamente). O conteúdo polínico total no ar atmosférico também foi variável no intervalo de 7240 a 12524 grãos/m3. Mais de 90% do alergeno foi encontrado na fracção de bioaerossóis de PM>10µm. O conteúdo em Ole e 1 foi directamente proporcional ao número de grãos de pólen no ar atmosférico, tendo-se encontrado uma correlação positiva entre os valores diários dos dois parâmetros. Comparando as épocas estudadas, os conteúdos totais de Ole e1 e de pólen não foram proporcionais, tendo-se observado que a carga alergénica por grão de pólen variou mais de 3x. Conclusões: Estes resultados sugerem que o Ole e 1 está preferencialmente associado aos grãos de pólen. Os conteúdos em pólen e Ole e 1 variaram inter-anualmente, tendo a carga alergénica dos grãos de pólen sido diferente. Este trabalho poderá assim contribuir para o desenvolvimento de um indicador que permita melhorar a previsão do risco de exposição a aeroalergenos. Agradecimentos: Este foi realizado no âmbito do projecto europeu HIALINE (Executive Agency for Health and Consumers, grant agreement No 2008 11 07)

Poor disability outcomes in the management of Low Back Pain patients in Portugal

Trabalho apresentado em 10th Interdisciplinary World Congress on Low Back & Pelvic Girdle Pain, 28-31 de outubro 2019, Antuérpia, BélgicaN/

National Assessment of Human Health Effects of Climate Change in Portugal: Approach and Key Findings

In this study we investigated the potential impact of climate change in Portugal on heat-related mortality, air pollution–related health effects, and selected vectorborne diseases. The assessment used climate scenarios from two regional climate models for a range of future time periods. The annual heat-related death rates in Lisbon may increase from between 5.4 and 6 per 100,000 in 1980–1998 to between 8.5 and 12.1 by the 2020s and to a maximum of 29.5 by the 2050s, if no adaptations occur. The projected warmer and more variable weather may result in better dispersion of nitrogen dioxide levels in winter, whereas the higher temperatures may reduce air quality during the warmer months by increasing tropospheric ozone levels. We estimated the future risk of zoonoses using ecologic scenarios to describe future changes in vectors and parasites. Malaria and schistosomiasis, which are currently not endemic in Portugal, are more sensitive to the introduction of infected vectors than to temperature changes. Higher temperatures may increase the transmission risk of zoonoses that are currently endemic to Portugal, such as leishmaniasis, Lyme disease, and Mediterranean spotted fever

Experimental validation of finite elements model in hip fracture and its clinical applicability

La fractura de la extremidad proximal de fémur es objeto de interés en investigación. La complejidad del entramado óseo y la ineficiencia estructural asociada al envejecimiento hacen que existan muchas variables todavía por comprender desde el punto de vista experimental, pero no existe un modelo de investigación estructural y biomecánico de la fractura de cadera claramente definido. La hipótesis de este trabajo es que es posible desarrollar un modelo de experimentación computacional que caracterice el hueso de la extremidad proximal del fémur como un material heterogéneo a partir de la traslación directa de los parámetros mecánicos obtenidos de piezas anatómicas de experimentación. Resultados: El modelo computacional fue capaz de determinar el punto de inicio de la fractura, con una discreta tendencia a la medialización anatómica de dicho punto respecto a lo ocurrido de manera experimental. El grado de correlación fue muy alto al comparar el valor real de deformación progresiva de las muestras frente al obtenido por el modelo computacional. Sobre 32 puntos analizados, se obtuvo una pendiente de 1,03 en regresión lineal, con un error relativo entre las deformaciones del 6% y un coeficiente de Pearson de R2=0,99. El modelo computacional infraestimó discretamente la carga máxima de fractura, con un error relativo aproximado al Conclusión: El modelo computacional de AEF desarrollado por este equipo investigador mul-tidisciplinar se puede considerar, en conjunto, un modelo completo de AEF de la extremidad proximal del fémur con aplicabilidad clínica futura al ser capaz de simular e imitar el compor-tamiento biomecánico de fémures humanos contrastado con un modelo experimental clásico realizado en piezas anatómicas. Sobre esta base podrán evaluarse interacciones cualitativas y cuantitativas que lo consoliden como un potente banco de ensayos de experimentación computacional sobre el fémur proximal humano.Fracture of the proximal extremity of the femur is the subject of research interest. The complexity of the bone framework and the structural inefficiency associated with ageing leave many variables yet to be understood from an experimental perspective. However, there is no clearly defined structural and biomechanical research model for hip fracture. The hypothesis of this paper is that it is possible to create a computational experimentation model that characterises the bone of the proximal extremity of the femur as a heteroge-neous material from directly translating the mechanical parameters obtained from anatomical experimentation specimens. Material and method: An experimental paper comparing real experimentation on cadavers and a numerical model based on finite element analysis (FEA). The variables uses were: the start point of the fracture, propagation of the fracture, progressive load and maximum load until fracture. The real mechanical parameters obtained from the anatomical specimens were transla-ted to the computational model based on the relationship between the Hounsfield units of the high resolution CAT scan and the bone mineral density of each virtual element, whereas the propagation of the fracture was modelled by the research team's own computational design, reducing the mechanical properties of the damaged elements as the fracture line advanced. Results: The computational model was able to determine the start point of the fracture, with a slight tendency towards anatomical medialisation of this point compared to what happened experimentally. The degree of correlation was very high on comparing the real value of progres-sive deformation of the samples compared to that obtained by the computational model. Over 32 points analysed, a slope of 1.03 in lineal regression was obtained, with a relative error bet-ween the deformations of 16% and a Pearson's coefficient of R2=0,99. The computational model slightly underestimated the maximum fracture load, with a relative error of approximately 10%. Conclusion: The FEA computational model developed by this multi-disciplinary research team could be considered, as a whole, a complete FEA model of the proximal extremity of the femur with future clinical applicability since it was able to simulate and imitate the biomechanical behaviour of human femurs contrasted with a traditional experimental model made from anato-mical specimens. On this basis, qualitative and quantitative interactions can be assessed which consolidate it as a powerful computational experimentation test bench for the human proximal femur