Impact of ankle foot orthosis stiffness on Achilles tendon and gastrocnemius function during unimpaired gait

Impact of ankle foot orthosis stiffness on Achilles tendon and gastrocnemius function during unimpaired gait

Ankle foot orthoses (AFOs) are designed to improve gait for individuals with neuromuscular conditions and have also been used to reduce energy costs of walking for unimpaired individuals. AFOs influence joint motion and metabolic cost, but how they impact muscle function remains unclear. This study...

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Bibliographic Details
Published in:Journal of biomechanics Vol. 64; pp. 145 - 152
Main Authors: Choi, Hwan, Peters, Keshia M., MacConnell, Michael B., Ly, Katie K., Eckert, Eric S., Steele, Katherine M.
Format: Journal Article
Language:English
Published: United States Elsevier Ltd 07-11-2017
Elsevier Limited
Subjects:
Achilles tendon
Achilles Tendon - physiology
Adult
Ankle
Ankle foot orthoses
Biomechanical Phenomena
Bone surgery
Cerebral palsy
Costs
Energy costs
Feet
Female
Foot Orthoses
Gait
Gait - physiology
Gastrocnemius
Gastrocnemius muscle
Humans
Kinematics
Knee
Male
Metabolism
Motion capture
Muscle, Skeletal - physiology
Musculoskeletal modeling
Orthoses
Range of Motion, Articular - physiology
Rehabilitation
Stiffness
Tendons
Three dimensional printing
Ultrasonic imaging
Ultrasound
Walking
Gait
Achilles tendon
Ankle foot orthoses
Musculoskeletal modeling
Stiffness
Gastrocnemius
Ultrasound
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Description
Summary:Ankle foot orthoses (AFOs) are designed to improve gait for individuals with neuromuscular conditions and have also been used to reduce energy costs of walking for unimpaired individuals. AFOs influence joint motion and metabolic cost, but how they impact muscle function remains unclear. This study investigated the impact of different stiffness AFOs on medial gastrocnemius muscle (MG) and Achilles tendon (AT) function during two walking speeds. We performed gait analyses for eight unimpaired individuals. Each individual walked at slow and very slow speeds with a 3D printed AFO with no resistance (free hinge condition) and four levels of ankle dorsiflexion stiffness: 0.25Nm/°, 1Nm/°, 2Nm/°, and 3.7Nm/°. Motion capture, ultrasound, and musculoskeletal modeling were used to quantify MG and AT lengths with each AFO condition. Increasing AFO stiffness increased peak AFO dorsiflexion moment with decreased peak knee extension and peak ankle dorsiflexion angles. Overall musculotendon length and peak AT length decreased, while peak MG length increased with increasing AFO stiffness. Peak MG activity, length, and velocity significantly decreased with slower walking speed. This study provides experimental evidence of the impact of AFO stiffness and walking speed on joint kinematics and musculotendon function. These methods can provide insight to improve AFO designs and optimize musculotendon function for rehabilitation, performance, or other goals.
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ISSN:0021-9290
1873-2380
DOI:10.1016/j.jbiomech.2017.09.015