Journal article
Reliability of a Novel Approach to Assessing Ankle Stiffness with and Without an Ankle Foot Orthosis
Journal of prosthetics and orthotics, Vol.38(1), pp.e23-e27
01/2026
DOI: 10.1097/JPO.0000000000000571
Abstract
Introduction
Ankle-foot orthosis (AFO) stiffness influences limb mechanics during gait; however, objective AFO stiffness data are lacking in most publications. Furthermore, when included, AFO stiffness is typically measured using mechanical testing systems that do not consider the limb-AFO-footwear interface.
Objective
The purpose of this study was to determine the reliability and responsiveness of a method for assessing passive ankle stiffness that accounts for limb-AFO-footwear interactions.
Study Design
Randomized cross-over study where passive ankle stiffness of 20 able-bodied individuals was measured without and with an AFO. Five trials were collected before (pre) and after (post) walking.
Methods
Lower-limb motion and loading were tracked using motion capture and force measurement systems, respectively. Participants were seated in a wheelchair with a weight placed on the distal thigh to axially load the lower leg. The whole body was moved forward to move the ankle into dorsiflexion, while electromyography was used to visually verify limited muscle activation. Passive ankle stiffness was quantified as the slope of the ankle moment (Nm) versus ankle angle (degrees).
Results
Average passive ankle stiffness did not significantly differ between pre and post trials (P > 0.05) for either condition but was significantly greater with the AFO than without at both times (P < 0.05). Intraclass correlation coefficients were greater than 0.8 and minimal detectable change values were less than 0.4 Nm/deg for both conditions, with the AFO and without.
Conclusions
This testing method can reliably assess passive ankle stiffness, is responsive to AFO related changes in passive ankle stiffness, and can be implemented in gait analysis laboratories with little added time or equipment.
Clinical Relevance
The ability to measure passive ankle stiffness while accounting for limb-AFO-footwear interactions would more closely describe the effects of the AFO when used by patients. The results of this study will likely benefit future AFO prescription and research examining the effect of AFO type or design on ankle stiffness and resulting performance of daily activities.
Details
- Title: Subtitle
- Reliability of a Novel Approach to Assessing Ankle Stiffness with and Without an Ankle Foot Orthosis
- Creators
- Kirsten M. Anderson - University of IowaJason M. Wilken - Department of Physical Therapy and Rehabilitation Science, Carver College of Medicine, University of Iowa, Iowa City, IA, United States
- Resource Type
- Journal article
- Publication Details
- Journal of prosthetics and orthotics, Vol.38(1), pp.e23-e27
- DOI
- 10.1097/JPO.0000000000000571
- ISSN
- 1040-8800
- Grant note
- National Center for Advancing Translational Sciences Bio-Mechanical Composites National Center for Advancing Translational Sciences (http://data.elsevier.com/vocabulary/SciValFunders/100006108) W81XWH-18-1-0658 / U.S. Department of Defense (http://data.elsevier.com/vocabulary/SciValFunders/100000005) U.S. Department of Defense (http://data.elsevier.com/vocabulary/SciValFunders/100000005) National Institutes of Health (http://data.elsevier.com/vocabulary/SciValFunders/100000002) UL1TR002537 / National Institutes of Health (http://data.elsevier.com/vocabulary/SciValFunders/100000002)
- Language
- English
- Electronic publication date
- 2025
- Date published
- 01/2026
- Academic Unit
- Physical Therapy and Rehabilitation Science
- Record Identifier
- 9984865312502771
Metrics
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