Evidence map›Paper›PMID 42642769›Full record

ArticleJournal of neuroengineering and rehabilitation2026

The variable stiffness orthosis: customizable mechanics for assistance and rehabilitation.

Nikko Van Crey, David Lam, Emily Bywater, Max Shepherd, Elliott Rouse

Abstract read
In one paragraph

Article in Journal of neuroengineering and rehabilitation, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 2 papers.

0numbers the graph read from it
0cells of the map it votes in
2citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

2 citing papers in PubMed.

  1. Article
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4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

5 authors.

Nikko Van CreyRobotics Department, University of Michigan, Hayward St, Ann Arbor, 48109, MI, USA. nikkovc@umich.edu.
David LamRobotics Department, University of Michigan, Hayward St, Ann Arbor, 48109, MI, USA.
Emily BywaterRobotics Department, University of Michigan, Hayward St, Ann Arbor, 48109, MI, USA.
Max ShepherdDepartment of Physical Therapy, Northeastern University, Huntington Ave, Boston, 02115, MA, USA.
Elliott RouseRobotics Department, University of Michigan, Hayward St, Ann Arbor, 48109, MI, USA.

Funding

Assessing Design Trade-Offs in an Orthosis with Enhanced Functionality and CustomizabilityF31HD115309 · NICHD · UNIVERSITY OF MICHIGAN AT ANN ARBOR · PI Emily Ann Bywater · 2024 to 2026
$144k
Eunice Kennedy Shriver National Institute of Child Health and Human Development AWD 1F31HD115309-01National Science Foundation Graduate Research Fellowship Program DGE- 1841052NICHD NIH HHS F31 HD115309
6 · The paper itself

Abstract

backgroundChallenges with community mobility are among the most prevalent disabilities worldwide, yet the passive orthoses available for daily use have remained largely unchanged for centuries. In contrast, the powered orthoses developed by researchers have advanced rapidly, but without a matching rate of user impact. To date, there are no powered ankle-foot orthoses available for daily use, stemming from challenges with reliability, safety, weight, noise, and cost. This work aims to explore the untapped potential of passive mechanisms, as a pathway that could more rapidly translate improved functionality to the people who rely on orthoses. To this end, we developed an orthosis with passive and quasi-passive mechanisms that render capabilities typically attributed to powered devices, blurring the line between powered and passive functionality.

methodsIn this work, we present the Variable Stiffness Orthosis, an ankle-foot orthosis that strikes a balance between powered and passive orthoses in terms of functionality and daily-use practicality. The Variable Stiffness Orthosis has torque-angle relationships that can be customized with a cam-based transmission, interchanged between gait phases with a cam-switching mechanism, and softened or stiffened between activities with a motorized spring support. These mechanisms enable precise control over the torque-angle relationship, including continuously variable stiffness, decoupled energy storage and return, step-to-step adjustment of stiffness magnitude, exchanging energy between gait phases, changing equilibrium angle between gait phases, negative stiffness, and extreme stiffness. These capabilities were validated on a rotary dynamometer and pilot tested on participants with and without sciatic nerve injury.

resultsDynamometer testing verified the capabilities of the VSO. In pilot testing, the participants had activity-dependent stiffness preferences spanning a large range. Using the VSO, the participant with sciatic nerve injury had reduced foot drop, increased total ankle moments, reduced biological ankle moments, reduced toe striking, and reduced steppage on their AFO side compared to walking with and without their daily-use device.

conclusionsThis work demonstrated that the passive and quasi-passive mechanisms within the VSO can replicate many powered functions, extending the capabilities of unpowered devices. The VSO also showed promise as a daily-use device, a clinical tool for orthotic prescription, and a research tool for investigating unexplored passive mechanics.

Indexed as

Foot OrthosesNeurological RehabilitationOrthotic DevicesBiomechanical PhenomenaEquipment DesignHumansAnkleAnkle-foot orthosisDesignExoskeletonExtreme stiffnessNegative stiffnessPassiveQuasi-passiveStiffnessVariable stiffness

Identifiers

PMID42642769
PMCPMC13504773

What OpenQuestion holds

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Registered trials

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.