The effect and mechanism of ankle-foot orthosis in patients with osteoarthritis of the knee

Abstract

Recently, ankle foot orthosis (AFS: Agilium Freestep) has been used for treatment in patients with osteoarthritis of the knee. However, there is a relative lack of research describing the mechanism of its effects. The purpose of this study was to examine the clinical aspects and to verify kinetics and kinematics effects in healthy subjects and patients with knee osteoarthritis. For the kinetics and kinematics analysis, we measured the lower limb joint angle and the knee joint moment of frontal plane using a three-dimensional motion analysis system. The results showed AFS generated resistance moment during the loading response. In addition, AFS could induce a normal coupling motion of foot pronation and tibial internal rotation, if the flexion motion of the knee and the retention of dorsiflexion at the time of initial contact of the ankle accompanied it during the loading response. This study also found that the first peak of the bimodal knee joint moment was decreased by AFS effects during the stance phase. Finally, motor learning of the normal kinematic chain could be promoted and also knee pain and difficulty of daily living would be improved by using AFS over a long-term period.