Anterior-posterior mobility of the talus in subjects with chronic ankle instability

Objectives: The effect of hypermobility or hypomobility of the talus in subjects with chronic ankle instability (CAI) has not been fully elucidated. The purpose of this study was to determine the anterior-posterior mobility of the talus in subjects with CAI. Design: Retrospective case-control study. Setting: Athletic training research laboratory. Participants: Fifteen subjects with unilateral CAI, and 15 subjects with no previous history of ankle injury participated in this study. Main outcomes measures: Anterior talar laxity was assessed with manual anterior drawer test and anterior drawer stress radiographs. Posterior talar hypomobility was assessed with a series of two posterior talar glide manual tests. Comparisons were made between the CAI and control groups and within sides of both groups. Results: The CAI group (mean=11.4±5.4 mm) had significantly more anterior talar displacement on both their ankles as measured on the stress views than did the control group (mean=6.7±4.7 mm). Interestingly, there was very little side to side difference between the involved and uninvolved ankles of the CAI group (11.5±5.6 vs. 11.3±5.4 mm). There were no significant differences involving either of the posterior talar glide measures or of the manual anterior drawer test. Conclusions: An increased amount of anterior talar mobility was demonstrated in the CAI group. Although all of our subjects reported unilateral CAI, increased laxity was present in both their unstable and healthy ankles.