Does chronic ankle instability involve independent factors? A factor analysis on the Cumberland Ankle Instability Tool in infantry soldiers

Objective: The Cumberland Ankle Instability Tool (CAIT) has been widely used to evaluate ankle perceived instability. The aim of this study was to determine whether infantry soldiers with and without previous ankle sprain reported different factors within the CAIT, and whether these factors are associated with physical performance. Design: Cross-sectional study. Settings: Military base. Participants: Seven-hundred and nineteen male infantry soldiers aged 18–21, completed the CAIT, previous sprains questionnaire and were assessed for anthropometric and functional abilities (proprioception, dynamic balance and agility). Main outcome measures: Factor analysis was performed on CAIT items, with Eigenvalue set to 1.5. Pearson correlations were performed between the factors extracted and the anthropometrics and functional abilities measurements, and independent T-tests were used to analyze associations between the factors and previous ankle sprains. Results: Three factors were extracted: functional stability (factor 1), ankle rolling (factor 2) and functional performance (factor 3). Significant differences were found in participants’ self-rating on factors 1 and 2, between soldiers with and without previous sprain (p < 0.001, p < 0.001 for factors 1–2, respectively). Correlations with anthropometric and functional abilities were weak. Conclusions: CAIT items can be clustered into three factors of perceived instability, providing military clinicians with valuable insights for targeted interventions.