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

Abstract

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