Chronic ankle instability: evolution of the model.

Area of Science:

• Orthopedics
• Sports Medicine
• Biomechanics

Background:

• The Hertel model is a common but potentially limited framework for understanding chronic ankle instability (CAI).
• CAI involves a continuum of mechanical and functional instability, often with recurrent sprains.
• A modified model is proposed to account for independent or combined instability components.

Purpose of the Study:

• To evaluate the fit of existing and proposed models of CAI using patient data.
• To identify functional impairments in different CAI subgroups compared to a healthy control group.

Main Methods:

• A cross-sectional study involving adults and adolescent dancers with and without CAI.
• Data collected included clinical assessments (e.g., Cumberland Ankle Instability Tool, anterior drawer test) and functional performance (balance tasks, inversion perturbation recovery time).
• Statistical analysis (Cohen d) was used to compare CAI subgroups with controls.

Main Results:

• The proposed CAI model demonstrated a superior fit to the data compared to the Hertel model (100% vs. 56.5% fit).
• Perceived instability was the most common classification (42.6%), followed by recurrent sprain with perceived instability (30.5%).
• All CAI subgroups exhibited poorer balance and recovery from perturbation than controls, with specific impairments noted for perceived instability and recurrent sprain groups.

Conclusions:

• The proposed model provides a more comprehensive framework for understanding chronic ankle instability.
• Perceived instability, alone or combined with recurrent sprains, characterizes the majority of individuals with CAI.
• Distinct functional deficits correlate with specific CAI classifications, aiding in targeted interventions.