Center of Mass and Ankle Inclination Angles during Walking: an Alternative Detection of Gait Instability

Instantaneous inclination angles between the whole body center of mass (COM) and center of pressure (COP) during gait were reported to detect gait instability in the elderly [1]. Accurate calculation of the COP requires a single foot placement on each force plate. However, many studies indicated that older adults, especially fallers, walk with a significantly smaller step than young adults [2,3]. Such gait modification and inter-trial inconsistency of this population greatly increase difficulty in obtaining a clean foot placement on the force plate, which will hinder the calculation of COM-COP inclination angles. Therefore, the purpose of this study was to find an alternative parameter, similar to COM-COP inclination angles, for assessing instantaneous alignment between COM and base of support during gait without the concern of the subject’s ability in making proper foot contacts with the force plate. Effectiveness to identify patients with imbalance using the inclination angle formed by the lateral ankle marker and COM during gait was assessed in this study.