PROLONGED REACTION-TIME IN PATIENTS WITH CHRONIC LATERAL INSTABILITY OF THE ANKLE

Impaired proprioception has been suggested as one cause of chronic lat eral instability of the ankle. We subjected 15 ankles in 13 patients w ith symptoms of chronic lateral instability to sudden angular displace ment. The reaction times in the peroneus longus and the tibialis anter ior muscles were recorded and compared with those from 15 control ankl es. Significantly longer ipsilateral reaction time was recorded in the patients (65 ms) compared with the controls (49 ms). We concluded tha t delayed proprioceptive response to sudden angular displacement of th e ankle may predispose an individual to or be a cause of chronic later al instability of the ankle.