Design, construction and evaluation of an electromechanical stance-control knee-ankle-foot orthosis.

A new electromechanical Stance-Control Knee-Ankle-Foot Orthosis (SCKAFO) was designed to provide improved gait for people with knee-extensor weakness. This SCKAFO inhibits knee flexion at any knee angle while allowing knee extension during weight bearing. During swing or other non-weight bearing activities, the SCKAFO allows free knee motion. A prototype joint was mechanically tested to determine the moment at failure, loading behaviour, and device safety. Quantitative kinematic gait analysis of three able-bodied subjects and three knee-ankle-foot-orthosis (KAFO) users showed that the new SCKAFO had a desired minimal effect on able-bodied walking gait. The SCKAFO permitted a mean increase in sagittal knee motion (488%) during swing for the three KAFO users and a reduction in pelvic obliquity and hip abduction angle abnormalities during terminal stance and swing for two KAFO users.