Low-load eversion force sense, self-reported ankle instability, and frequency of giving way.
BACKGROUND
Functional ankle instability has been attributed to proprioceptive loss. However, in previous studies of proprioception,authors have not investigated the ability to sense force at the ankle. Additionally, previous investigators have viewed functional ankle instability as either a present or absent condition,rather than a continuum.


OBJECTIVE
To determine the relationship of ankle giving-way frequency and perceived ankle instability to ankle eversion force sense.


METHODS
Cohort design.


METHODS
Sports medicine research laboratory.


METHODS
Twenty individuals (5 men,15 women) with a history of unilateral ankle instability.


METHODS
We tested subjects with 2 loads: 10% and 30% of maximal voluntary isometric contraction.


METHODS
We measured eversion force sense by calculating absolute, constant, and variable errors from a 3-trial force-matching procedure. Furthermore, subjects reported their frequency of giving way in units of times per day,week, or month, and these data were extrapolated to estimate annual giving-way frequency. Finally, subjects answers to 6 questions about ankle stability during typical daily or sports activities were summed to create a perceived ankle instability index.


RESULTS
Significant relationships were found for only the 10% maximal voluntary isometric contraction. For absolute error,a positive relationship existed between the number of self reported episodes of giving way and eversion force sense for both ipsilateral (r .58) and contralateral (r .49) testing of the injured ankle. Constant error was correlated with giving way(r = -.56) for ipsilateral testing of the injured ankle. The ankle instability index was also positively correlated with eversion force sense absolute error (r .51) for ipsilateral testing only.


CONCLUSIONS
Our results suggest that subjects with ankle instability had difficulty replicating eversion forces. Specifically,larger errors were related to both self-reported giving-way episodes and perceived ankle instability.
Arnold
Brent L
BL
Virginia Commonwealth University, Richmond, VA, USA. barnold@vcu.edu.
Docherty
Carrie L
CL