Ankle dorsiflexion range of motion influences Lateral Step Down Test scores in individuals with chronic ankle instability

Objectives To determine differences in ankle dorsiflexion range of motion (ROM) between three groups of individuals with chronic ankle instability (CAI) based on Lateral Step Down Test quality of movement. The secondary purpose was to quantify the relationship between ankle dorsiflexion ROM and Lateral Step Down Test scores. Design Descriptive laboratory study. Setting University research laboratory. Participants Fifty-nine participants with CAI. Main outcome measures Differences in ankle dorsiflexion ROM between three Lateral Step Down Test movement quality groups (good, moderate, poor) was determined using an analysis of variance. The relationship between outcome variables was determined using a Spearman rank correlation coefficient. Results Significantly less ankle dorsiflexion ROM was observed in individuals with poor movement quality (36.0 ± 6.6°) compared to good (42.3 ± 6.4°). Individuals with moderate movement quality did not have ankle dorsiflexion ROM (39.1 ± 6.2°) that was significantly different from either group. There was a negative correlation (r = −0.39) between ankle dorsiflexion ROM and Lateral Step Down Test scores. Conclusions Participants in the poor movement quality group had 6° less ankle dorsiflexion ROM than participants in the good movement quality group. While ankle dorsiflexion ROM is associated with Lateral Step Down Test scores additional factors likely contribute to movement dysfunction in individuals with CAI. Trial registry This trial was registered on ClinicalTrials.gov (NCT01438905).