Interest of Evaluating the Movement of the Center of Mass in a Dynamic Avoidance Task as the Endpoint of the Dynamic Equilibrium of Hemiplegic Patients

Overview

For several years, the postural disorders assessment in hemiplegic patients was conducted through force plate, using the center of plantar pressure displacement in a static position. These are widely used in physical therapy both for assessment and rehabilitation of patients with balance disorders. For hemiplegic patients, an asymmetric distribution support on each foot and an increased surface area of postural sways (more marked on the medio lateral axis) are observed. These studies, based on the study of plantar pressure ,are not enough to providea full description of the spatio-temporal organization of postural components in hemiplegic patients. Indeed, postural stabilometric evaluation is based on a simplification of the human skeleton by considering it as a simple inverted pendulum swinging on his ankles. This simplified model can't be used in dynamic assessment because of the simultaneous contributions of several joints during movement. This restricts its clinical interest because patients are more exposed to imbalances and falls in dynamic situations. Thus, the hip angular movement results in a center plantar pressure displacementwhich is impossible to discriminate from the ankle axis movement using stabilometric signal only. Thus, it seemed interesting to study another variable valid in dynamic conditions : the displacement of center of mass during a dynamic balancing task. This variable is obtained through 3D motion capture of the different segments of the human body. The dynamic test is a dynamic postural assessment following ball avoidance from three different directions. The center of mass displacement will be compared with a functional test known to be representative of dynamic balance of the individual capacities: The Timed Up and Go test (TUG). All of this data aims to improve the hemiplegic postural assessment for physical therapy and to help develop new rehabilitative approaches.