Orthotic devices in functional treatment of ankle sprain. Stabilizing effects during real movements.

Various orthotic devices generally employed for therapy of ankle sprain were tested under functional conditions. The experimental setup comprised inversion stimuli of 20 and 30 degrees (13 subjects) while standing on a tiltplatform as well as running movements of 8 and 12 km.h-1 on a treadmill (12 subjects). Ankle joint displacements were registered together with the surface EMGs from mm. peroneus long., tibialis ant., gastrocnemius med. and vastus med. In an additional study the relation between achilles tendon angle and talar tilt was determined under static conditions. Ten subjects with chronical instability were examined both in uni- and bipedal stance with the foot inverted to 20, 30 and 40 degrees. None of the tested devices could reduce achilles tendon angle movements completely neither during a sudden inversion nor during running. However, there were significant differences among the tested devices in the dorsal-plantar and in the eversion-inversion plane. In bipedal stance talar tilts were observed only when the foot was inverted more than 30 degrees. In unipedal stance these tilts were clearly reduced or disappeared totally. It is concluded that for functional rehabilitation, loading of the ankle joint is desirable in order to increase joint stability. The central importance of the treatment by orthotic devices may be regarded in an optimal passive joint stabilization combined with a correct fitting in order to preserve proprioceptive neuromuscular function for an active muscular stabilization.