The Short Form Health Survey SF 36 was used as a comparative questionnaire as well as the French Cumberland Ankle Instability Tool CAIT F . ...The other subscales of the SF 36 mental health were weakly correlated with the AII F, reflecting good divergent validity. An optimal cut off score was obtained to dissociate pathological patients from healthy subjects: when the subject responded to "yes" 5 times or more, he is considered, with a very high degree of confidence, to be pathological. ...