The effect of changing plantarflexion resistive moment of an articulated ankle–foot orthosis on ankle and knee joint angles and moments while walking in patients post stroke

Abstract

Background The adjustment of plantarflexion resistive moment of an articulated ankle-foot orthosis is considered important in patients post stroke, but the evidence is still limited. Therefore, the aim of this study was to investigate the effect of changing the plantarflexion resistive moment of an articulated ankle-foot orthosis on ankle and knee joint angles and moments in patients post stroke. Methods Gait analysis was performed on 10 subjects post stroke under four different plantarflexion resistive moment conditions using a newly designed articulated ankle-foot orthosis. Data were recorded using a Bertec split-belt instrumented treadmill in a 3-dimensional motion analysis laboratory. Findings The ankle and knee sagittal joint angles and moments were significantly affected by the amount of plantarflexion resistive moment of the ankle-foot orthosis. Increasing the plantarflexion resistive moment of the ankle-foot orthosis induced significant decreases both in the peak ankle plantarflexion angle (P<0.01) and the peak knee extension angle (P<0.05). Also, the increase induced significant increases in the internal dorsiflexion moment of the ankle joint (P<0.01) and significantly decreased the internal flexion moment of the knee joint (P<0.01). Interpretation These results suggest an important link between the kinematic/kinetic parameters of the lower-limb joints and the plantarflexion resistive moment of an articulated ankle-foot orthosis. A future study should be performed to clarify their relationship further so that the practitioners may be able to use these parameters as objective data to determine an optimal plantarflexion resistive moment of an articulated ankle-foot orthosis for improved orthotic care in individual patients.

Reduction of genu recurvatum through adjustment of plantarflexion resistance of an articulated ankle-foot orthosis in individuals post-stroke

“…An articulated AFO with plantarflexion resistance-adjustable joints was used (Kobayashi et al, 2015) (Figure 1A). The plantarflexion resistance of the AFO was altered by exchanging a steel spring, resulting in 4 different spring rates (S1, S2, S3 and S4).…”

“…The markers were placed directly on the AFO, and dynamic tracking was accomplished using a rigid cluster on the upright above ankle joint (Kobayashi et al, 2015). The initial angle (i.e.…”

“…(A) The articulated ankle-foot orthosis (AFO) used in this study, (B) Plantarflexion resistance characteristics of the AFO under 4 spring conditions (S1, S2, S3 and S4) (Kobayashi et al, 2015). …”

“…Previous studies suggest that the amount of plantarflexion resistance of articulated AFOs affect knee joint kinetics and kinematics in a heterogeneous group of individuals post stroke: a mixture of individuals with or without genu recurvatum (Kobayashi et al, 2015). However, examining the groups with genu recurvatum separately and individually may be important to develop a better understanding.…”

An articulated ankle–foot orthosis with adjustable plantarflexion resistance, dorsiflexion resistance and alignment: A pilot study on mechanical properties and effects on stroke hemiparetic gait

“…The resistance of an AFO (resistance to plantarflexion and the resistance to dorsiflexion) is a key mechanical characteristic that influences sagittal motion of the ankle and knee joints during gait [1, 2]. Alignment is another important characteristic of the AFO that determines the ankle joint angle where the resistances are initiated.…”