Reduced Effective Postural Responses to External Perturbations in Chronic Ankle Instability

Area of Science:

• Biomechanics
• Motor Control
• Sports Medicine

Background:

• Chronic ankle instability (CAI) is linked to postural control deficits, especially during dynamic movements and external disturbances.
• The precise nature of postural stability and joint actions in CAI during such events requires further clarification.

Purpose of the Study:

• To investigate differences in postural responses to mediolateral platform perturbations during single-leg stance in individuals with CAI versus healthy controls (HC).
• To identify how joint torques contribute to postural stability in CAI during perturbed balance.

Main Methods:

• Twenty-three CAI participants and 23 HC participants underwent a single-leg stance balance task with a 1-second mediolateral platform perturbation.
• Ground reaction forces and kinematic data were collected to calculate the margin of stability (MoS) and frontal plane joint torques.

Main Results:

• The CAI group demonstrated a significantly increased MoS during platform movement changes and after the platform stopped compared to the HC group (p<0.05).
• A weaker correlation between MoS and hip/trunk torque was observed in the CAI group, indicating less effective joint action for postural control.
• Sudden changes in the base of support effectively identified postural impairments in CAI.

Conclusions:

• Individuals with CAI exhibit a less stable postural strategy and reduced effectiveness of joint actions during perturbed single-leg stance.
• Dynamic balance tasks involving sudden base of support alterations are valuable for detecting postural deficits in CAI.
• Further research should explore potential interventions to improve these identified postural impairments in CAI.