An Assistive Knee-Ankle-Foot-Orthosis and Sit-to-Stand Biomechanics

Knee-Ankle-Foot-Orthoses (KAFOs) are leg braces designed to assist in standing for patients with limited lower extremity function. The brace holds the knee extended and the ankle in a neutral position, thereby controlling balance and joint alignment. KAFOs have a variety of applications from skeletal complications to muscular weakness and paralysis (1). Patients experiencing such conditions are often dependant on the use of a wheelchair. Standing, therefore, becomes an important physiological function with benefits including pressures relief, spasticity reduction, bowel-and-bladder management, among others (2). However, since a KAFO limits knee and ankle motion, rising from a chair becomes a significant challenge as it requires substantial upper body strength to hoist oneself from seated position. Consequently, many KAFO users are unable to achieve sit-to-stand (STS) independently.