Contour representation of sway area in posturography and its application

The representation of postural sway tendency in posturography is important to understand the features of body balance system and a variety of postural disorders. This study is concerned with the contour representation and analysis of postural sway trajectory in posturography. We propose two methodologies to derive the contour of postural sway based on the boundary points of sway area. An algorithm for finding the sway contour in each method was developed, and the experiments were performed to examine the computational efficiency between the methods proposed. Fourteen able-bodied men were asked to stand upright on a force platform to compare the numerical measures of sway shape with other quantitative sway measures used in previous research into balance. The results show that numerical measures of sway contour (area, perimeter, and complexity of sway shape) and radius length diagram can be used to describe the tendency of sway shape, whereas other quantitative sway measures represent the extent of sway amounts.