Technical validation of a body-weight controlled clutch for ankle-foot orthoses of children with cerebral palsy

Ankle-foot orthoses (AFOs) greatly improve gait in patients with Cerebral Palsy (CP). Some AFO designs allow for passive push-off support, however, these often limit the ankle’s ROM during the swing phase of gait. This contribution presents the technical validation of a body-weight controlled clutch (BWC) designed for children with CP, to passively engage and disengage the push-off support without restricting ankle kinematics. We determined the friction coefficient (μ) of different BWC prototypes, and used it as an indicator for the amount off force that can be exerted on the mechanism before slippage occurs. Four clutch configurations were tested, containing a rigid or flexible spacer and a nylon strapping webbing or neoprene rubber slider. The best tested configuration was the one composed by the rigid spacer–nylon slider combination, which yielded a μ as high as 0.98. We envision that a lightweight solution like the BWC presented here can benefit new AFO designs to support push-off on children with gait deficiencies.