EFFECT OF AN ANKLE ORTHOSIS AND ANKLE LIGAMENT ANESTHESIA ON ANKLE JOINT PROPRIOCEPTION

The purposes of this study were to determine the effect of a rigid ank le orthosis (Aircast Air-Stirrup) and lateral ankle ligament anesthesi a on ankle joint proprioception. Twelve noninjured subjects attempted to match nine reference ankle joint positions with their eyes closed b efore and after application of the ankle brace and before and after on e or two of the lateral ankle ligaments (anterior talofibular and calc aneofibular) were anesthetized. Three-dimensional ankle joint orientat ions were recorded with a Motion Analysis system. No significant diffe rences in the constant, variable, or absolute error were seen between subjects in the non-anesthetized and anesthetized conditions (P > 0.05 ), regardless of whether one or two ligaments were anesthetized. Thus, it appears that ligament mechanoreceptors contributed little to ankle joint proprioception, and that the afferent feedback f rom skin, musc le, and other joint receptors was adequate for the positioning task of the present study. Both the variable and absolute error in matching t he reference positions were significantly less with the orthosis than without (P < 0.05). Application of an orthosis may increase the affere nt feedback from cutaneous receptors in the foot and shank, which may in turn lead to an improved ankle joint position sense.