Study Design Case-control study.

Objectives To explore self-reported responses for differentiating CAI(chronic ankle instability) and lateral ankle sprain(LAS)-Coper status.

Background Self-reported instability and disability in conjunction with patient history have been used to differentiate CAI and LAS-Copers, but certain self-reported evaluation tools, such as the Identification of Functional Ankle Instability (IdFAI), may contain some redundancy. It remains unknown if other potential patient history items in concert with selected items from the IdFAI could create more efficient identification of CAI and LAS-Copers.

Methods and Measures Data were extracted from 241 participants enrolled in previous laboratory studies that compared CAI(n=128) and LAS-Coper(n=113) groups classified by the guidelines of the International Ankle Consortium. Responses on each item of the IdFAI were examined, and patients responded if they had received formalised rehabilitation for their previous LAS(Y/N). Chi-square analyses were used to explore response distributions.

Results Many of the items on the IdFAI resulted in statistically significant response distributions. Of note, 84% of CAI patients responded their ankle gives way(item#6) at least monthly, while 98.8% of LAS-Copers answered yearly or never(p<0.001). Similarly, 85.8% of CAI patients felt their ankle was unstable at least monthly during sport activity(item#10), while 96.4% of LAS-Copers responded yearly or never(p<0.001). More CAI patients reported using crutches than LAS-Copers (item#4)(p=0.006), but distribution of performing rehabilitation was not significantly different between the cohorts(p=0.06).

Conclusions The frequency of giving-way and feeling unstable seems to differentiate CAI versus LAS-Copers effectively, which could be used to focus the categorization of patients with a history of LAS with the deficits that need addressing, while utilisation of crutches and initial rehabilitation was less definitive. Additional exploration on the severity of the previous LAS, and the interactions with utilisation of crutches and participation in rehabilitation is needed to shape future interventions for those with LAS history.