Assessing Functional Ankle Instability with Joint Position Sense, Time to Stabilization, and Electromyography

<jats:sec sec-type="context"><jats:title>Context:</jats:title><jats:p>Functional ankle instability (FAI) is difficult to identify and quantify.</jats:p></jats:sec><jats:sec sec-type="objective"><jats:title>Objective:</jats:title><jats:p>To compare joint position sense (JPS), time to stabilization (TTS), and electromy-ography (EMG) of ankle musculature in recreational athletes with and without FAI.</jats:p></jats:sec><jats:sec sec-type="design"><jats:title>Design:</jats:title><jats:p>Case-control compared with <jats:italic>t</jats:italic> tests and ANOVAs.</jats:p></jats:sec><jats:sec sec-type="setting"><jats:title>Setting:</jats:title><jats:p>Sports medicine research laboratory.</jats:p></jats:sec><jats:sec sec-type="participants"><jats:title>Participants:</jats:title><jats:p>20 recreational athletes.</jats:p></jats:sec><jats:sec sec-type="main outcome measures"><jats:title>Main Outcome Measures:</jats:title><jats:p>Passive angle reproduction, TTS, and mean EMG amplitude of the tibialis anterior, peroneals, lateral gastrocnemius, and soleus muscles during single-leg-jump landing.</jats:p></jats:sec><jats:sec sec-type="results"><jats:title>Results:</jats:title><jats:p>No differences in JPS or medial-lateral TTS measures between groups. Significantly longer anterior-posterior TTS (<jats:italic>P</jats:italic> < .05) in the unstable ankle group. The stable ankle group had significantly higher mean EMG soleus amplitude after landing (<jats:italic>P</jats:italic> < .05). No other significant differences were found for mean EMG amplitudes before or after landing.</jats:p></jats:sec><jats:sec sec-type="conclusions"><jats:title>Conclusions:</jats:title><jats:p>Subjects with FAI demonstrated deficits in landing stability and soleus muscle activity during landing that may represent chronic adaptive changes following injury.</jats:p></jats:sec>