An evaluation of the posterior leaf spring orthosis using joint kinematics and kinetics.

The primary function of the posterior leaf spring orthosis (PLS) is to prevent excessive equinus or drop foot in swing. The name of the orthosis, posterior leaf "spring," suggests that it also mechanically augments push-off in stance. The purpose of this study was to determine the effect of the PLS on ankle function by using computerized gait-analysis techniques. Multiple barefoot versus brace walks were compared in 31 children with cerebral palsy. Results indicate that the PLS reduces excessive equinus in swing and is sufficiently flexible to allow ankle dorsiflexion in midstance. In terminal stance, the peak power-generating capabilities of the ankle were reduced when the child was wearing the PLS. Energy results indicate that more mechanical energy was absorbed during midstance and less produced during terminal stance with the PLS. Therefore, the PLS improved ankle function but did not augment ankle function through storage and return of mechanical, or spring, energy.