Slower nerve conduction velocity in individuals with functional ankle instability.

The purpose of this study is to quantify nerve conduction velocity differences in individuals with functional ankle instability compared to a "healthy" population. 38 participants ages 18-30 were recruited from a large university with approximately 43,000 students. 19 subjects (9 men and 10 women; age=21.0±1.4 years; height=172.0±9.3 cm; mass=74.4±1 2.4 kg) with symptoms of functional ankle instability were in the functional ankle instability group. 19 subjects (10 men, 9 women; age=22.0±2.6 years; height=169.8±9.1 cm; mass=69.0±14.8 kg) with "healthy" ankles were in the control group. Nerve conduction velocity was conducted using one trial at 2 different sites: posterior to the fibular head (fibular), and 10 cm superior/posterior of the first site (popliteal). Nerve conduction velocity (m/sec) was assessed using a SierraWave II system (Cadwell Laboratories; Kennewick, WA). A MANCOVA was performed on the two dependent variables (fibular and popliteal). Covariates included surface temperature of the leg, body mass index, and age. The independent variable was group (functional ankle instability and control). The effect of group was significantly related to nerve conduction velocity at the fibular site (F(1, 27) =16.49, p=0.01) and popliteal site (F(1, 27)=4.51, p=0.01), with responses significantly faster for individuals in the control group than the functional ankle instability group. These results indicate that patients with functional ankle instability might have damage to the peroneal nerve which results in slower peroneal nerve conduction velocity.