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Effect of unilateral functional instability of the ankle on inversion and eversion strength and postural sway

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
David H. Perrin, Provost and Executive Vice Chancellor (Creator)
Institution
The University of North Carolina at Greensboro (UNCG )
Web Site: http://library.uncg.edu/

Abstract: Objective: The purpose of this study was to determine if individuals with unilateral functional ankle instability had decreased ability to maintain postural sway, as well as decreased isokinetic eccentric strength of ankle evertors and invertors. Design and Setting: Subjects with no previous history of ankle injury were compared with subjects with functional ankle instability on the following tests: isokinetic eccentric inversion and eversion strength and measures of single-limb postural sway. Subjects: Eighteen subjects participated in this study: 9 subjects in the functional instability (FI) group (age = 22.89 ± 3.18 yr, ht = 181 ± 6.0 cm, wt = 80.25 ± 12.2 kg) and 9 noninjured (NI) controls (age = 26.22 ± 2.34 yr, ht = 170 ± 10.0 cm, wt = 65.08 ± 12.03 kg). Measurements: Subjects performed postural sway assessment on a balance system under static and dynamic conditions. Ankle inversion and eversion eccentric strength were evaluated at 90°/sec using an isokinetic dynamometer. Additionally, we assessed the degree of mechanical instability in the Fl group with a series of stress radiographs. Results: No significant differences in single-limb postural sway measures or in eversion strength between limbs in the Fl group or between groups were found. A significant group-bylimb interaction was present in inversion peak torque; however, post hoc testing revealed the only difference to be between the dominant and nondominant limbs of the NI group. Conclusions: Postural sway and inversion and eversion eccentric peak torque are not affected by functional instability of the ankle. Alternate methods of postural sway assessment and ankle strength measurement are discussed as possible areas for future study.

Additional Information

Publication
Journal of Athletic Training, 32: 226-232
Language: English
Date: 1997
Keywords
Balance, Peak Torque, Ankle Sprain, Joint Posi­tion Sense, Proprioception, Peroneal Muscle