Multiplanar Stiffness of Commercial Carbon Composite Ankle-Foot Orthoses
- DoD-VA Extremity Trauma and Amputation Center of Excellence, San Antonio, TX 78234, Center for Limb Loss and Mobility, VA Puget Sound, 1660 S Columbian Way, Seattle, WA 98108
- DoD-VA Extremity Trauma and Amputation Center of Excellence, San Antonio, TX 78234, Center for Limb Loss and Mobility, VA Puget Sound, 660 S Columbian Way, Seattle, WA 98108, Department of Mechanical Engineering, University of Washington, Seattle, WA 98195
The mechanical properties of an ankle-foot orthosis (AFO) can impact how a user's movement is either restricted or augmented by the device. However, standardized methods for assessing stiffness properties of AFOs are lacking, posing a challenge for comparing between devices and across vendors. Therefore, the purpose of this study was to quantify the rotational stiffness of thirteen commercial, nonarticulated, carbon composite ankle-foot orthoses. A custom, instrumented test fixture, for evaluating mechanical properties in rotating exoskeletons (EMPIRE), deflected an AFO through 20 deg of plantar/dorsiflexion motion about a specified, but adjustable, ankle axis. Sagittal, frontal, and transverse plane rotational stiffness were calculated, and reliability was assessed between cycles, sessions, and testers. The EMPIRE demonstrated good-to-excellent reliability between testers, sessions, and cycles (intraclass correlation coefficients all ≥0.95 for sagittal plane stiffness measures). Sagittal plane AFO stiffness ranged from 0.58 N·m/deg to 3.66 N·m/deg. AFOs with a lateral strut demonstrated frontal plane stiffnesses up to 0.71 N·m/deg of eversion while those with a medial strut demonstrated frontal plane stiffnesses up to 0.53 N·m/deg of inversion. Transverse plane stiffnesses were less than 0.30 N·m/deg of internal or external rotation. These results directly compare AFOs of different models and from different manufacturers using consistent methodology and are intended as a resource for clinicians in identifying a device with stiffness properties for individual patients.
- Research Organization:
- Oak Ridge Associated Universities (ORAU), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-06OR23100
- OSTI ID:
- 1982928
- Journal Information:
- Journal of Biomechanical Engineering, Vol. 144, Issue 1; ISSN 0148-0731
- Publisher:
- ASME
- Country of Publication:
- United States
- Language:
- English
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