Development of a Method to Determine Abnormal Joint Torque Coupling Patterns During Walking In Chronic Hemiparetic Stroke

Motor impairments following stroke may lead to a reduced walking ability, however, no reliable assessments to quantify these impairments during walking are available [1]. For example, abnormal joint torque coupling between hip extension and hip adduction, previously reported under isometric conditions [2], has not been assessed during walking. Since this coupling might lead to instability, our aim was to develop a method to quantify joint torque coupling during walking.
We developed a method to modulate hip extension torques and measure its effect on hip abduction torques. A motor was attached to the pelvis and a constant force was applied in anterior/posterior direction during walking. Preliminary results of two healthy participants and one stroke survivor indicate that hip torques during stance phase of walking can be modulated by applying forces in the anteroposterior direction at the pelvis. In all participants, applying forces in posterior direction led to larger hip extension torques compared to normal walking whereas forces in anterior direction resulted in opposite responses. These changes were accompanied by similar but smaller changes in hip abduction.
Based on these preliminary findings, we conclude that applying forces in the anteroposterior direction at the pelvis can be used to manipulate joint torque patterns during walking. Future experiments will focus on investigating whether stroke survivors show abnormal coupling during walking. This is expected to provide new insight into the effect of joint torque coupling patterns on walking ability following stroke and may lead to the development of specific therapies to improve stability during gait.