Sit-to-Stand Biomechanics and the Design of an Assistive Knee-Ankle- Foot-Orthosis

Sit-to-stand (STS) transfer is a prerequisite for many daily tasks. Literature often assumes symmetrical behavior across the body (bilateral symmetry) during healthy STS. However; little research has been conducted to validate this assumption. Motion analysis was utilized to evaluate STS in 10 healthy males. Asymmetry was found in the peak joint moments (JM) and ground reaction forces. Asymmetry was also characterized over the whole STS movement. This analysis suggested evaluating peak values alone may not fully represent asymmetry present during this movement.

A knee-ankle-foot-orthosis (KAFO) augments weight bearing in populations with lower extremity weakness by holding the knee extended and ankle neutral. However, this creates complications for users performing STS. A novel KAFO attachment was designed to generate a knee extension moment, thus alleviating these challenges. Testing on an able bodied participant and a finite element analysis indicate the design has the potential to assist KAFO users.