Those with Unilateral Chronic Ankle Instability have Impaired Unilateral Single Limb Balance and Self-Reported Function

Abstract

Chronic ankle instability (CAI) is a common sequela of an ankle sprain. Single limb balance impairments have been reported in those with CAI, but it is unclear whether these deficits are found on only the self-reported more dysfunctional limb or if they are bilateral. PURPOSE: To determine whether single limb balance deficits exist when comparing the self-reported CAI limb to the healthy limb in subjects with unilateral CAI. METHODS: 26 subjects with self-reported unilateral CAI participated. Each participant completed the Foot and Ankle Ability Measure Sport Scale (FAAMS). A score of <80% on the FAAMS was considered as an ankle with CAI. All subjects performed 3, 10-second trials of single limb stance with eyes open on a force plate and 3, 20-second trials of single limb balance on a firm surface (SLBT) with eyes closed. From the force plate, time-to-boundary was calculated in the mediolateral (TTBML) and anteroposterior (TTBAP) directions. TTB estimates the amount of time a person has to make a postural correction to prevent balance loss. Dependent variables included the FAAMS score (%), TTBAP and TTBML (s), and mean errors committed during the SLBT. Paired t-tests were used to compare the dependent variables between limbs (self-reported CAI vs. healthy limb) for all comparisons. Alpha was set a priori at p<0.05 for all analyses. RESULTS: The CAI limb (64.2±11.7%) had lower FAAMS scores than the healthy limb (98.1±5.6%, p<0.001). TTBML (CAI: 1.8±0.7s, Healthy: 2.1s, p<0.001) and TTBAP (CAI: 4.9±1.4, Healthy: 5.8±1.9s, p<0.001) were lower on the CAI limb. The CAI limb (CAI: 2.49±1.55) also had more SLBT errors than the healthy limb (1.77±1.48, p=0.006) CONCLUSION: Those with unilateral CAI reported significantly more disability when performing sport-related activities on the CAI limb relative to the healthy limb. These individuals, while balancing on the CAI limb, had significantly less time to make postural corrections in both the ML and AP directions with eyes open. Similarly, these individuals also made more errors on an eyes closed clinical balance test on the CAI limb. Based on these results, less time to make postural corrections with eyes open and more errors with eyes closed may be contributing factors for the reported CAI limb disability. This project was supported by: NIAMS 1R03AR061561.