Passive knee prostheses require a significant amount of additional metabolic energy to carry out a gait cycle, therefore affecting the natural human walk performance. Current active knee prostheses are still limited because they do not reply with accuracy of the natural human knee movement, and the time response is relatively large. This paper presents the design and control of a new biomimetic-controlled transfemoral knee prosthesis based on a polycentric-type mechanism. The aim was to develop a knee prosthesis able to provide additional power and to mimic with accuracy of the natural human knee movement using a stable control strategy. The design of the knee mechanism was obtained from the body-guidance kinematics synthesis based on real human walking patterns obtained from computer vision and 3D reconstruction. A biomechanical evaluation of the synthesized prosthesis was then carried out. For the activation and control of the prosthesis, an echo-control strategy was proposed and developed. In this echo-control strategy, the sound side leg is sensed and synchronized with the activation of the knee prosthesis. An experimental prototype was built and evaluated in a test rig. The results revealed that the prosthetic knee is able to mimic the biomechanics of the human knee.
This paper presents the analysis of human gait of three young adults under several walking conditions similar to those in real life. The aim is to evaluate how the human gait varies when different walking conditions are considered. In order to evaluate the human gait variations under different walking conditions, first a 3D computer vision system to reconstruct human gaits is developed and presented. Then, a set of kinematic gait parameters is defined in order to analyse the different gait patterns. Finally, several experiments are conducted with three normal young adults walking under different real-life conditions, such as ascending a slope walk, no arm-swing walk, carrying a front load walk, carrying a lateral load walk, fast walk and high-heel shoes walk. The results has shown that the human gait pattern vary according to the walking conditions, being the most common variation a slower walk with shorter steps than the normal walk. Since the aim of the paper is to identify and evaluate human gait variations under different walking conditions, only three subjects were considered in the study. However, in order to provide more precise and standard results the number of subjects must be increased considering different age, height, sex, weight, and health conditions of the participants. Human walking patterns are very important for medical diagnosis and orthopedics, pathological and aging evaluation, medical rehabilitation, and design of rehabilitation systems, human prosthesis and humanoid robots. However, most of the research work in the literature has been primarily focused on the analysis of gait patterns under normal walking conditions. This fact has led to a limited knowledge of the human gait patterns since real-life walking conditions are diverse, e.g. walking carrying a load. This paper presents the analysis of human gait of three young adults under walking conditions similar to those in real life. Human gait patterns vary with the walking conditions, which must be considered during the analysis, evaluation and diagnosis of gait performance, or during the design process of prostheses or rehabilitation systems.
A guerra é um momento transcendente na história das nações. Este artigo resgata as percepções subjetivas que definem a realidade moral da guerra. Para isso, são analisados os discursos de guerra apresentados no Chile e no Peru durante a Guerra do Pacífico. Os discursos belicosos são considerados artefatos culturais que dão sentido ao conflito. A hipótese deste artigo discute a existência de um discurso racista articulado a partir da realidade histórica e ideológica da época. Nos discursos estão as figuras do ‘roto’ e do ‘cholo’, a ser seus arquétipos nacionais que servem para homogeneizar e exacerbar aquelas qualidades consideradas essenciais dos povos em conflito. Este trabalho é atribuído à abordagem que estuda as linguagens políticas, colocando sua atenção para o contexto em que se articulam e desarticulam os dis-cursos. As fontes utilizadas são, principalmente, jornais e proclamações do período
Introducción La luxación expuesta de rodilla es compleja, de incidencia baja con grandes secuelas funcionales. Existen escasos reportes de series en la literatura relativos a su manejo y resultados. Objetivo El objetivo de este trabajo fue describir los resultados obtenidos de todos los pacientes con luxación expuesta de rodilla tratados durante las últimas dos décadas en nuestro hospital bajo un mismo estándar de tratamiento. Método Estudio descriptivo retrospectivo en una serie quirúrgica de 11 pacientes con luxación expuesta de rodilla, tratados entre 1994 y 2015. Todos fueron estudiados y manejados según esquema estandarizado: Angiografía/ angioTC, aseo quirúrgico, fijador externo y reparación neurovascular en casos necesarios. Revisión de registros clínicos e imagenológicos consignando datos demográficos, lesiones concomitantes, número y tipo de cirugías, y complicaciones asociadas. Seguimiento promedio fue de 10,7 años con evaluación mediante encuesta funcionales SF-12/IKDC durante el mes de marzo de 2015. Resultados Diez pacientes eran hombres, 1 mujeres. Edad promedio al accidente 38,6 años. Mecanismo lesional de alta energía; como referencia la clasificación de Schenck, 1 lesión III-M, 4 tipo IV y los 6 restantes una tipo V. 4 lesiones vasculares (36.4%) y 7 lesiones neurológicas (63.6%). Tratamiento definitivo consistió en 4 reconstrucciones ligamentarias, 2 prótesis, 3 artrodesis y 2 amputaciones supracondíleas. Evaluaciones funcionales dieron como resultados un puntaje promedio de 37 y 48,5 para SF-12 físico y mental respectivamente, y de 44,1 para IKDC. Conclusión La luxación expuesta de rodilla es una lesión infrecuente, muy compleja, asociada a accidentes de alta energía, con complicaciones severas, lo que determina resultados funcionales relativamente malos. La estandarización permite sistematizar las distintas etapas de atención, racionalizar los recursos disponibles evitando la improvisación en momentos críticos, lo que podría incidir en la obtención de resultados.Nivel de Evidencia IV Serie de casos.
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