The purpose of the study is actually the translation, cultural adaptation and psychometric validation in the Italian Version of the Identification of Functional Ankle Instability (IdFAI) English Version for use in outpatient clinics in non-English subjects to objectify chronic ankle instability.

The hypothesis is to translate and culturally adapt the scale successfully and demonstrate a good factorial structure and psychometric properties, replicating the results of the original English version of the questionnaire

Participants without ankle sprain.

1. Age ≥ 18aa
2. Speak Italian on a daily basis
3. No pathologies or surgical treatments in the lower limbs currently or in the past

Participants with ankle sprain.

Inclusion Criteria

1. Age ≥ 18aa
2. Speak Italian on a daily basis
3. At least one ankle sprain
4. Recurrent sprain to the same ankle and/or sensation of ankle instability and/or 'giving way'

Exclusion Criteria

1. Inability to understand written Italian
2. Acute lower extremity injury occurred in the three months preceding the compilation of the questionnaire
3. History of others lower extremity musculoskeletal diseases or injuries of other joints (i.e, hip, knee), previous ankle fractures or systemic pathologies (i.e., neurological disorders, rheumatoid arthritis) currently or in the past
4. History of surgical treatments in either lower limb (bones, joints, nerves)

Adult subjects, speaking Italian, without lower limbs current disease or history of lower limbs disease or surgical tretmens in the lower limbs.

Adult subjects, speaking Italian, with at least one ankle sprain and recurrent sprain to the same ankle and/or sensation of ankle instability and/or 'giving way'