Rehabilitation Engineering
Robabe Vatanparast; Hossein Karimi; Fariba Bahrami; Roya Narimani
Volume 3, Issue 3 , June 2009, , Pages 171-178
Abstract
CNS applies Anticipatory Postural Adjustments (APA) strategy to reject or minimize perturbation during different voluntary movements. The postural control mechanisms associated with voluntary arm movement (rapid arm rising) in below knee amputees (BKA) was investigated and the results were compared with ...
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CNS applies Anticipatory Postural Adjustments (APA) strategy to reject or minimize perturbation during different voluntary movements. The postural control mechanisms associated with voluntary arm movement (rapid arm rising) in below knee amputees (BKA) was investigated and the results were compared with the normal subjects. Biomechanical variables including ground reaction forces and displacements of the center of pressure were used to investigate the APA in BKA. Six below knee amputees and six control subjects stood on a force plate under three conditions: 1. with both feet on the platform, 2. with right foot (prosthetic foot) and 3. with left foot on the plate. For each condition, the task was repeated 10 times. At the same time, a camera recorded the task performance. The recorded data were used to determine the start moment of the movement. The instant at which, for the first time before starting the movement, any one of the recorded biomechanical variables deviated from its initial value was considered as the beginning of the APA. To increase the validity of the test, efforts were made to match the subjects with regards to their age, gender, cause of amputation and prosthesis types. Our results indicated that the center of pressure in the BKA participants showed greater displacements in medial-lateral and anterior-posterior directions. It was also observed that the vertical components of the ground reaction forces, when the right foot was on the plate, were increased. There were no significant differences in other biomechanical variables between the two groups. We may conclude that the voluntary arm movement perturbs the posture in the BKA participants more than in the control group. The BKA participants shifted their weight to the intact limb by the anticipation of the disturbance to avoid balance loosing. Therefore, in our study the intact limb in below knee amputee subjects played an important role in the balance control. Based on our results, we suggest considering the role of the intact limb in the rehabilitation programs and strengthening the muscles of both limbs as a major part of theses programs.
Rehabilitation Engineering
Hamed Ghomashchi; Ali Esteki; Ali Motie Nasrabadi
Volume 2, Issue 2 , June 2008, , Pages 95-107
Abstract
In this study, the underlying dynamics of postural control system during quiet standing were investigated. Single-subject (SS) analysis was used as the statistical technique to compare the results. Center of pressure (COP) trajectories of 21 trials of a standing healthy subject and 24 trials of a cerebrovascular ...
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In this study, the underlying dynamics of postural control system during quiet standing were investigated. Single-subject (SS) analysis was used as the statistical technique to compare the results. Center of pressure (COP) trajectories of 21 trials of a standing healthy subject and 24 trials of a cerebrovascular attacked (CVA) patient were considered in our analysis. Complexity, dimensionality and stability of postural balance control system were evaluated using the first local minimum of auto mutual information (AMI) function, correlation dimension (Dc) and largest lyapunov exponent (LLE), respectively. The results indicated higher time delays (higher determinism), lower correlation dimension (lower active dynamical degrees of freedom) and lower LLE (increase of local stability) in the postural steadiness time series of the CVA patient in compare with the normal subject. The results showed that these measures not only can be used as pathologic measures to distinguish healthy subjects from CVA patient but also provide us new openings to disclose the postural control mechanism during a quiet standing.
