Desenvolvimento de um sistema óptico de medição não invasiva para a análise dinâmica do movimento escapular

Abstract

The analysis of scapular motion is a very complex task but of great importance for clinical practice. Several methods have been proposed so far to evaluate scapular rotations during the elevation of the humerus in the scapular plane. Meanwhile, the International Society of Biomechanics standardized important concepts of its measurement. Although the use of electromagnetic sensors is, presently, considered the most precise among the many measurement techniques, it is a highly invasive and time consuming method, which restricts its use to research labs as rather a standard, less applicable to daily clinical practice. The main purpose of this work was, hence, to propose an alternative, new measurement technique which is not invasive, less time consuming, easy to use, but still, strictly follows international standards. In order to achieve this goal, fringe projection was combined with Fourier Transform Technique as a tool to freeze and extract, at moments of interest, the topographic maps of the human back during scapular motion. Once landmarks were selected within these topographic maps their respective rotation angles could be calculated. The proposed system was composed of a CCD camera, a multimedia projector and a host computer. The camera captured several snap shots of fringes projected onto the human back during scapular motion. Adequate computer processing of images was achieved by a general user interface developed in a MATLAB environment. The performance of the new measurement system was evaluated and clinically tested with the participation of 09 healthy individuals. A metrological analysis of the proposed system is also presented. A maximum error of ± 3° was estimated for the measurement of scapular rotation angles, comparable to other already established methods. The new system demonstrated to be robust, easy to set up and use, requires only little preparation of the subject, therefore, making it a practical tool for routine clinical analysis of scapular motion.