Postural stability measures as diagnostic tools for chronic ankle instability: a comprehensive assessment

Area of Science:

• Biomechanics
• Sports Medicine
• Rehabilitation Science

Background:

• Chronic ankle instability (CAI) involves recurrent sprains and persistent symptoms, leading to impaired postural control.
• Accurate diagnostic tools are needed to differentiate CAI from healthy individuals and guide treatment.

Purpose of the Study:

• To evaluate the diagnostic utility of linear and nonlinear postural stability measures in individuals with CAI.
• To identify key metrics for distinguishing CAI from healthy controls.

Main Methods:

• Assessed postural stability in 24 participants (12 CAI, 12 controls) using a force platform under various surface and visual conditions.
• Measured linear (e.g., sway area, mean velocity) and nonlinear (e.g., approximate entropy, correlation dimension) parameters of center of pressure (COP).
• Utilized Receiver Operating Characteristic (ROC) analysis to determine diagnostic accuracy and cutoff scores.

Main Results:

• CAI participants demonstrated increased mediolateral COP sway and mean velocity on hard surfaces, and deficits in sway area and mean velocity on soft surfaces with eyes closed.
• ROC analysis confirmed strong diagnostic accuracy for several linear and nonlinear measures.
• Elevated approximate entropy (ApEn) and reduced correlation dimension (CD) in CAI indicated greater postural irregularity and reduced dynamic stability, with Rsw and ApEn showing strong diagnostic power on hard surfaces with eyes open.

Conclusions:

• Linear and nonlinear postural stability measures effectively differentiate individuals with CAI from healthy controls.
• Key metrics like Rsw, MV, ApEn, and CD possess significant diagnostic value for early CAI detection.
• Integrating these measures into clinical practice can enhance CAI management and patient outcomes.