Effect of lateral ankle ligament anesthesia on single-leg stance stability.

PURPOSE This study was designed to determine, in isolation, the contribution of lateral ankle ligament mechanoreceptors to postural stability during single leg static (eyes open, eyes closed) and landing tasks. METHODS Fourteen healthy subjects (nine males, five females) underwent two different treatment conditions (control, anesthesia) in a counterbalanced order (48-h interval). During the anesthetic treatment, lidocaine was injected into the anterior talofibular and calcaneofibular ligament (1.5 cc each) regions. Postural stability was measured using forceplate and kinematic variables. The average of each variable across multiple trials under each treatment for the three tasks was analyzed statistically. RESULTS Results of all statistical analyses failed to demonstrate significant alterations (P > 0.05) in postural control attributable to the treatment condition. CONCLUSION These results suggest that lateral ankle ligament mechanoreceptors either do not make a significant contribution to single leg stance stability, do not have a unique, irreplaceable role, or have a role that is too subtle to be detected given the measurement techniques used. Thus, the idea that single leg stability becomes altered after ankle joint injury because of proprioceptive disruption was not supported. This would suggest that reported postural control alterations in persons after repetitive ankle injury more likely occur as a result of alterations in mechanical stability, motor components, and/or central motor programming.