Design, Development, and Evaluation of a Bionic Knee-Ankle-Foot Orthosis Retrofit for Walking Gait Normalization

A knee-ankle-foot orthosis (KAFO), which covers the knee, ankle and foot, can mitigate abnormal walking pattern caused by weak quadriceps. Several types of KAFOs are currently available in the market: passive KAFOs, stance-control KAFOs and dynamic KAFOs. In passive KAFOs, the knee joint keeps being locked during standing and walking, and can be unlocked manually to allow free rotation for sitting. Stance-control KAFOs (SCKAFOs) allow free knee motion during swing phase when the braced leg is unloaded. Dynamic KAFOs are able to reproduce normal walking ability throughout whole gait cycle. This research is directed at using superelastic alloys to develop a dynamic knee actuator that can be mounted on a traditional passive KAFO. The actuator stiffness can match that of a normal knee joint during the walking gait cycle. This proposed knee actuator utilizes a storing-releasing energy method to apply functional compensation to the knee joint, controlling the knee joint during both stance and swing phases. Fundamentally, the knee actuator is composed of two distinct parts which are connected with the thigh and shank segments, respectively. There are two superelastic actuators that are housed within these two parts and activated independently. Each actuator is developed by combining a superelastic rod and a rotary spring in series. When neither actuator is engaged, the knee joint is allowed to rotate freely. The stance actuator works only in the stance phase and the swing actuator is active for the swing phase. The conceptual design of the knee actuator is verified using numerical simulation and a prototype is developed through additive manufacturing for confirming the concept.

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Effect of ankle-foot orthosis on level walking in healthy subjects

Proceedings of the Institution of Mechanical Engineers Part H Journal of Engineering in Medicine ◽

10.1177/0954411919880359 ◽

2019 ◽

Vol 233 (12) ◽

pp. 1262-1268

Author(s):

Mizuki Kato ◽

Arinori Kamono ◽

Naomichi Ogihara

Keyword(s):

Ground Reaction Force ◽

Healthy Subjects ◽

Sagittal Plane ◽

Reaction Force ◽

Walking Ability ◽

Vertical Ground Reaction Force ◽

Walking Gait ◽

Ankle Foot Orthosis ◽

Heel Contact ◽

Foot Orthosis

An ankle-foot orthosis is often prescribed in the rehabilitation of patients with neurological motor disorders such as hemiparesis. However, walking with a unilateral ankle-foot orthosis may not be effectively achieved just by trying to reproduce normal intact walking with a symmetrical gait pattern. Understanding skills to facilitate walking gait with a unilateral ankle-foot orthosis has implications for better rehabilitative interventions to help restore walking ability in patients with stroke. We, therefore, analyzed the kinematics and ground reaction forces of walking with and without an ankle-foot orthosis in healthy subjects to infer the possible skills to facilitate walking gait with a unilateral ankle-foot orthosis. Adult male participants were asked to walk with and without an ankle-foot orthosis across two force platforms set in a wooden walkway, and body kinematics and ground reaction force profiles in the sagittal plane were simultaneously recorded. We found that the forward tilting angle of the trunk at the time of toe-off of the leg with the ankle-foot orthosis was significantly larger than that of the leg without the ankle-foot orthosis, to adaptively compensate for the loss of ankle joint mobility due to the unilateral ankle-foot orthosis. Furthermore, the peak vertical ground reaction force at heel-contact was significantly larger in the leg without the ankle-foot orthosis than in the leg with the ankle-foot orthosis owing to the fact that the stance phase duration of the leg with the ankle-foot orthosis was relatively shorter. Such information may potentially be applied to facilitate walking training in stroke patients wearing a unilateral ankle-foot orthosis.

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The Araz medial linkage orthosis—a new orthosis for walking in patients with spinal cord injury: A single patient study

Prosthetics and Orthotics International ◽

10.1177/0309364613492169 ◽

2013 ◽

Vol 38 (2) ◽

pp. 155-159 ◽

Cited By ~ 1

Author(s):

Mokhtar Arazpour ◽

Monireh A Bani ◽

Stephen W Hutchins ◽

Meysam Sayyadfar

Keyword(s):

Spinal Cord ◽

Spinal Cord Injury ◽

Step Length ◽

Gait Velocity ◽

Walking Gait ◽

Ankle Foot Orthosis ◽

Cord Injury ◽

Spinal Cord Injury Subject ◽

Solid Works ◽

Foot Orthosis

Background:This article describes the development and evaluation of a new medial linkage orthosis to potentially assist paraplegic patients to ambulate.Case description and methods:The orthosis was initially designed using the solid works program and was subsequently evaluated when used by a spinal cord injury subject to test the structure during standing and walking. Gait analysis was used to compare the medial linkage orthosis to a standard hip–knee–ankle–foot orthosis.Findings and outcomes:The results demonstrated improvements in gait velocity, step length, and decreased compensatory motions in the new orthosis compared to the hip–knee–ankle–foot orthosis.Conclusions:The results propose that this new Araz medial linkage orthosis could be used to assist paraplegic subjects who have adequate ranges of motion and also with weakness or reduced tone to stand and walk.Clinical relevanceThe Araz medial linkage orthosis can potentially provide standing and walking assistance for spinal cord injury patients.

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Lightweight, modular knee-ankle-foot orthosis for duchenne muscular dystrophy: Design, development, and evaluation

Archives of Physical Medicine and Rehabilitation ◽

10.1016/s0003-9993(95)80126-x ◽

1995 ◽

Vol 76 (12) ◽

pp. 1156-1162 ◽

Cited By ~ 13

Author(s):

Diane M. Taktak ◽

Peter Bowker

Keyword(s):

Duchenne Muscular Dystrophy ◽

Muscular Dystrophy ◽

Design Development ◽

Ankle Foot Orthosis ◽

Foot Orthosis

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Effectiveness of an ankle–foot orthosis on walking in patients with stroke: a systematic review and meta-analysis

Scientific Reports ◽

10.1038/s41598-021-95449-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Yoo Jin Choo ◽

Min Cheol Chang

Keyword(s):

Stride Length ◽

Walking Speed ◽

Sagittal Plane ◽

Meta Analysis ◽

Step Length ◽

Stride Time ◽

Plane Angle ◽

Ankle Foot Orthosis ◽

Biomechanical Parameters ◽

Foot Orthosis

AbstractWe conducted a meta-analysis to investigate the effectiveness of ankle–foot orthosis (AFO) use in improving gait biomechanical parameters such as walking speed, mobility, and kinematics in patients with stroke with gait disturbance. We searched the MEDLINE (Medical Literature Analysis and Retrieval System Online), CINAHL (Cumulative Index to Nursing and Allied Health Literature), Cochrane, Embase, and Scopus databases and retrieved studies published until June 2021. Experimental and prospective studies were included that evaluated biomechanics or kinematic parameters with or without AFO in patients with stroke. We analyzed gait biomechanical parameters, including walking speed, mobility, balance, and kinematic variables, in studies involving patients with and without AFO use. The criteria of the Cochrane Handbook for Systematic Reviews of Interventions were used to evaluate the methodological quality of the studies, and the level of evidence was evaluated using the Research Pyramid model. Funnel plot analysis and Egger’s test were performed to confirm publication bias. A total of 19 studies including 434 participants that reported on the immediate or short-term effectiveness of AFO use were included in the analysis. Significant improvements in walking speed (standardized mean difference [SMD], 0.50; 95% CI 0.34–0.66; P < 0.00001; I2, 0%), cadence (SMD, 0.42; 95% CI 0.22–0.62; P < 0.0001; I2, 0%), step length (SMD, 0.41; 95% CI 0.18–0.63; P = 0.0003; I2, 2%), stride length (SMD, 0.43; 95% CI 0.15–0.71; P = 0.003; I2, 7%), Timed up-and-go test (SMD, − 0.30; 95% CI − 0.54 to − 0.07; P = 0.01; I2, 0%), functional ambulation category (FAC) score (SMD, 1.61; 95% CI 1.19–2.02; P < 0.00001; I2, 0%), ankle sagittal plane angle at initial contact (SMD, 0.66; 95% CI 0.34–0.98; P < 0.0001; I2, 0%), and knee sagittal plane angle at toe-off (SMD, 0.39; 95% CI 0.04–0.73; P = 0.03; I2, 46%) were observed when the patients wore AFOs. Stride time, body sway, and hip sagittal plane angle at toe-off were not significantly improved (p = 0.74, p = 0.07, p = 0.07, respectively). Among these results, the FAC score showed the most significant improvement, and stride time showed the lowest improvement. AFO improves walking speed, cadence, step length, and stride length, particularly in patients with stroke. AFO is considered beneficial in enhancing gait stability and ambulatory ability.

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