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Final Program


Final Congress Guide

Biomedical Sciences

100 Section - Rearfoot motion during single-leg stance in individuals with chronic ankle instability

Tuesday, May 19, 2026
6:00 PM - 7:30 PM PT
Objectives : Lateral ankle sprains often develop into chronic ankle instability (CAI), causing impaired balance during single-leg stance (SLS). Previous study suggests excessive rearfoot pronation in CAI during dynamic movements. However, its relationship with mediolateral center of pressure (COP) sway remains unclear. This study aimed to clarify rearfoot kinematics and its relationship with COP in individuals with CAI during static SLS.

Design:

Participants included 12 individuals with CAI (history of LAS and Cumberland Ankle Instability Tool score ≤ 24) and 10 controls. The task was a SLS with closed eyes for 40 seconds each. Kinematic data and COP data were obtained using a three-dimensional motion analysis system and force plates. Retroreflective markers were attached based on the model developed by Leardini et al.
The relative angles of pronation and supination of the rearfoot relative to the tibia and mediolateral COP displacement were calculated. Additionally, the cross-correlation coefficient (r) between COP displacement and rearfoot angle was calculated. Statistical analyses were performed using unpaired t-tests, Welch's t-test, and Mann-Whitney U test. The significance level was set at 5%.

Results:

No significant differences were observed in demographic data between CAI and control groups. For rearfoot angle, the CAI group showed a significantly greater range of motion in the pronation direction than the control group (p< 0.05). There was no significant difference in the cross-correlation coefficient between the mediolateral COP displacement and the rearfoot angle displacement.
 

Conclusion:

In the present study, individuals with CAI showed excessive rearfoot pronation. Furthermore, the correlation coefficient between rearfoot motion and COP was high, but the variability of COP was maintained. Therefore, although postural stability itself is maintained, it is suggested that inefficient postural control may be occurring, requiring excessive rearfoot motion to achieve it.