Ankle instability effects on joint position sense when stepping across the active movement extent discrimination apparatus.

CONTEXT Individuals with and without functional ankle instability have been tested for deficits in lower limb proprioception with varied results. OBJECTIVE To determine whether a new protocol for testing participants' joint position sense during stepping is reliable and can detect differences between participants with unstable and stable ankles. DESIGN Descriptive laboratory study. SETTING University clinical laboratory. PATIENTS OR OTHER PARTICIPANTS Sample of convenience involving 21 young adult university students and staff. Ankle stability was categorized by score on the Cumberland Ankle Instability Tool; 13 had functional ankle instability, 8 had healthy ankles. INTERVENTION(S) Test-retest of ankle joint position sense when stepping onto and across the Active Movement Extent Discrimination Apparatus twice, separated by an interim test, standing still on the apparatus and moving only 1 ankle into inversion. MAIN OUTCOME MEASURE(S) Difference in scores between groups with stable and unstable ankles and between test repeats. RESULTS Participants with unstable ankles were worse at differentiating between inversion angles underfoot in both testing protocols. On repeated testing with the stepping protocol, performance of the group with unstable ankles was improved (Cohen d = 1.06, P = .006), whereas scores in the stable ankle group did not change in the second test (Cohen d = 0.04, P = .899). Despite this improvement, the unstable group remained worse at differentiating inversion angles on the stepping retest (Cohen d = 0.99, P = .020). CONCLUSIONS The deficits on proprioceptive tests shown by individuals with functional ankle instability improved with repeated exposure to the test situation. The learning effect may be the result of systematic exposure to ankle-angle variation that led to movement-specific learning or increased confidence when stepping across the apparatus.