Verifying the Independence of Anterior and Mediolateral Margin of Gait Stability Indices

Gait stability indices are used for the quantitative assessment of individual fall risk. The margin of stability (MoS) is a popular gait stability index. This index computes the fall risks in the anterior and mediolateral directions; however, the relationships between the anterior and mediolateral MoSs have not been studied. We analyzed the MoS values in these two directions and several gait parameters using canonical correlation analysis, and obtained the linear relationships between these two groups. The gait kinematic data of 300 strides of 60 elderlies from an open database were used for this analysis. Our analysis verified that the MoS values in the anterior and mediolateral directions exhibited a weak relationship. The anterior posture became stable as the anterior gait speed decreased or the cadence increased. Furthermore, gait motions with greater step widths exhibited higher mediolateral MoS values, indicating greater stability. These findings indicate that the anterior and mediolateral postural stabilities are independently related to different gait parameters, which can aid in understanding stable walking strategies.