Effect of a semi-rigid ankle stabilizer on performance in persons with functional ankle instability

Study Design: Within-group repeated measures. Objectives: To determine the effect of a semi-rigid prophylactic ankle stabilizer (PAS) on performance of subjects with post-acute, unilateral ankle sprains who have mechanically stable ankles, but are functionally impaired. Background: Most studies on PAS performance to date are limited to subjects with noninjured, nonimpaired ankles. No research has been reported to determine the effect PASs have on performance in subjects who have a mechanically stable, nonacute ankle sprain with functional impairment. Methods and Measures: Twenty-five subjects (8 men and 17 women; average height = 168.91 +/- 33.02 cm, average weight = 61.10 +/- 29.5 kg, and average age = 16.2 +/- 6 years) met the qualification criteria of the study. Subjects had unilateral grade I or II lateral ankle sprains of 3 to 4 weeks duration and were cleared medically to return to activities of daily living. Each subject's injured ankle was mechanically stable as determined by physical exam but was functionally impaired as determined by instability during the modified Rhomberg test. Separate 2 x 2 ANOVAs with repeated measures on brace condition (Aircast SportStirrup and nonbraced control) and test session (test session 1 and test session 2) were completed to assess the effect of ankle stabilization on 2 dependent variables 136.58-m shuttle-run and vertical-jump. Results: Shuttle-run time was significantly faster for the braced condition (mean = 9.43 +/- .72 seconds) than for the nonbraced control (mean = 9.57 +/- .75 seconds), regardless of test session. Shuttle-run time was significantly faster for test session 2 (mean = 9.43 +/- .79 seconds) than for test session 1 (mean = 9.57 +/- .68 seconds), regardless of brace condition. No significant main or interaction effects occurred for vertical-jump. Conclusions: Use of a semi-rigid PAS significantly increased shuttle-run but not vertical-jump performance. This effect was immediate and did not require PAS acclimation.