Biomechanical response to ankle–foot orthosis stiffness during running

• Published in: Clinical biomechanics (Bristol) Vol. 30; no. 10; pp. 1125 - 1132
• Main Authors: Russell Esposito, Elizabeth, Choi, Harmony S, Owens, Johnny G, Blanck, Ryan V, Wilken, Jason M
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.12.2015
• Subjects: Adult; Ankle - physiology; Ankle Joint - physiology; Biomechanical Phenomena; Braces; Equipment Design; Foot; Foot Orthoses; Gait - physiology; Humans; IDEO; Joint stiffness; Kinematics; Kinetics; Knee - physiology; Knee Joint - physiology; Limb salvage; Male; Mechanical work; Middle Aged; Military; Physical Medicine and Rehabilitation; Running - physiology; Walking - physiology; Joint stiffness; Mechanical work; IDEO; Kinematics; Limb salvage; Kinetics; Military
• ISSN: 0268-0033; 1879-1271
• DOI: 10.1016/j.clinbiomech.2015.08.014

Abstract Background The Intrepid Dynamic Exoskeletal Orthosis (IDEO) is an ankle–foot orthosis developed to address the high rates of delayed amputation in the military. Its use has enabled many wounded Service Members to run again. During running, stiffness is thought to influence an orthosis' energy storage and return mechanical properties. This study examined the effect of orthosis stiffness on running biomechanics in patients with lower limb impairments who had undergone unilateral limb salvage. Methods Ten patients with lower limb impairments underwent gait analysis at a self-selected running velocity. 1. Nominal (clinically-prescribed), 2. Stiff (20% stiffer than nominal), and 3. Compliant (20% less stiff than nominal) ankle–foot orthosis stiffnesses were tested. Findings Ankle joint stiffness was greatest in the stiffest strut and lowest in the compliant strut, however ankle mechanical work remained unchanged. Speed, stride length, cycle time, joint angles, moments, powers, and ground reaction forces were not significantly different among stiffness conditions. Ankle joint kinematics and ankle, knee and hip kinetics were different between limbs. Ankle power, in particular, was lower in the injured limb. Interpretation Ankle–foot orthosis stiffness affected ankle joint stiffness but did not influence other biomechanical parameters of running in individuals with unilateral limb salvage. Foot strike asymmetries may have influenced the kinetics of running. Therefore, a range of stiffness may be clinically appropriate when prescribing ankle–foot orthoses for active individuals with limb salvage.