Evidence of a different landing strategy in subjects with chronic ankle instability.

The purpose of the study is to evaluate the discriminative validity of the multiple hop test (MHT) for chronic ankle instability (CAI). The dynamic postural control of 51 CAI subjects and 52 uninjured controls was assessed using the MHT. To evaluate dynamic postural control, the type and number of balance errors were analysed and the time to complete the MHT was measured. Between-group differences of time scores and balance errors, identified as being change-in-support strategy errors (CSS) or fixed-support strategy errors (FSS), were assessed. The area under curve of the outcomes was determined and likelihood ratios (LRs) were calculated based upon their most optimal cut off point. When compared to uninjured controls, CAI subjects needed significantly more time to perform the test (p<0.001) and made significantly more CSS errors (p<0.001). When 1 positive outcome (time score or CSS errors) was considered as a criterion, the LR+ was 2 and the LR- 0.08. In the case of 2 positive outcomes (time score and CSS errors), the LR+ was 7.1 and the LR- 0.49. CAI subjects have an impaired dynamic postural control and rely on a different postural strategy to restore balance. The MHT has good discriminative validity for CAI.