On the biomechanical design of stance control knee ankle foot orthosis (SCKAFO)

Abstract

The main purpose of this research work is to design a dynamic Stance Control Knee-Ankle-Foot-Orthosis (SCKAFO) to support patients with gait disorders, namely for patients with muscular weakness and dystrophy in quadriceps femoris muscle group. Patients with quadriceps muscular weakness are regularly prescribed a Knee-Ankle-Foot-Orthosis (KAFO).This orthotic device locks the knee in the full extension during stance phase and remains locked during the swing phase. Due to the absence of knee flexion, the KAFO users must adopt abnormal gait patterns. These abnormal gait patterns lead to compensatory movements in order to overcome the weak muscular control. A new type of orthosis, referred as Stance-Control-Knee-Ankle-Foot-Orthosis (SCKAFO), has recently emerged to allow knee flexion during the swing phase while providing controlled knee flexion in stance phase In this work several commercial SCKAFO designs are presented and their limitations are discussed. A SCKAFO electromechanical knee locking system is proposed and its requirements can be established of the intended function the knee and ankle orthotic joints should feature in order to approach a normal gait. The new dynamic SCKAFO proposed in this work should have a superior performance when compared to those currently available in the market, and aspects such as weight, cost, type of actuation and metabolic cost will play a crucial role. The new orthotic device will allow a more natural gait pattern and consequently reducing metabolic cost. An improvement in this issue will be a huge effort in reducing the high rejection rate for these orthotic devices users.