Examination of Clinical and Laboratory Measures of Postural Stability During Static and Dynamic Testing Between Stable and Unstable Ankles

The purposes of this study were to (1) examine the relationship between clinical and laboratory balance testing, (2) to examine the effect of functional ankle instability (FAI) on scored dynamic and static clinical balance tests, (3) to examine the effect of functional ankle instability (FAI) on a timed dynamic clinical balance test, (4) to examine the effect of FAI on a dynamic laboratory balance test, and (5) to examine the effect of FAI on a static laboratory balance test. Each subject performed four balance tests; (1) Balance Error Scoring System (BESS) Test, (2) Agility Hop test, (3) Laboratory Static Balance Test, and (4) Jump Stabilization Test. There were two subject groups; control and FAI. Subjects within the FAI group had reported multiple (≥2) lateral ankle sprains, at least one of which required protected weight bearing (e.g. use of crutches), along with reports of the affected ankle "giving way" or of overall unilateral weakness. Score data from total number of errors were obtained from the BESS Test. Score data from total number of postural adjustments and time to completion (in seconds) were obtained from the Agility Hop test. Mean COP velocity (in meters/second) was obtained from the Laboratory Static Balance Test. Time to Stabilization (in seconds) was obtained from the Jump Stabilization Test. To determine a correlation between clinical and laboratory measures, three correlations were conducted; a comparison between the mean COP velocity and the BESS total error score, a comparison between the Time to Stabilization (TTS) and the timed Agility Hop test, and a comparison between the Time to Stabilization and the scored Agility Hop test. One-way ANOVAs were used to determine group differences for the BESS test, scored and timed Agility Hop test, Jump Stabilization Test, and mean COP velocity. All statistical significance values were set at p<0.05. The results of this study showed that all components of COP velocity were correlated with Total Error scores of the BESS test (AP COP velocity, r=0.655,p=0.001; ML COP velocity r=0.582, p=0.003; Total Resultant COP velocity, r=0.678, p=0.000). The results of this study also showed that individuals with FAI commit more errors than control subjects in the Clinical Dynamic test and certain components of the BESS test, along with taking longer to complete the Clinical Dynamic test. Individuals with FAI displayed a TTS of nearly 1.5 times longer as compared to control subjects in the anterior-posterior direction. The results of this study support the use of both BESS testing and the Agility Hop Test as methods to evaluate, progress through rehabilitation, and functionally clear an athlete with the presence of FAI in the absence of computerized postural stability measures.