Double-stopped ankle-foot orthosis in flaccid peroneal and tibial paralysis: evaluation of function.

This study was undertaken to evaluate how effectively an ankle-foot orthosis can substitute for paralyzed musculature, and to determine the forces it sustains in so doing. Timing of the events of gait, the ground reaction forces, their magnitude and location, and the brace moments were studied. Midstance phase was found lengthened at the expense of push-off phase. During push-off, vertical loading and posterior shear were markedly reduced by tibial block. Also, the dorsiflexion moment in the orthosis was correspondingly increased. The orthosis was found to substitute for muscle function in that it approximates the foot-ankle motion of heel-strike and allows a push-off substitute.