Bidirectional Tuning of the AFO Stiffness (NEUROSWING)

Optimizing Gait With Bidirectional Tuning of the Ankle-foot Orthosis (AFO) Stiffness in People With Lower Leg Muscle Weakness

The goal of this pilot study with a pre-post design is to investigate the effects of separate individualization of the AFO stiffness towards plantar- and dorsiflexion in a spring-hinged AFO on walking compared to a spring-like AFO (3 types) having the same stiffness in both directions.

People with a neuromuscular disease or nerve injury causing at least plantarflexor weakness (determined as the inability to perform 3 single heel rises), with an indication for or using an AFO, will be fitted with a new, custom-made spring-hinged AFO with the NEURO SWING® system ankle joint (Fior& Gentz, Lüneburg In Duderstadt, Germany), of which the stiffness of ventral and dorsal compartment of this spring-hinged AFO will be individualized. For comparison, measurements will be performed with three different prefab spring-like AFOs with different stiffness levels (but which have a similar stiffness towards plantar and dorsiflexion), and the participants' current AFO if applicable, and shoes-only at baseline.

The main outcome parameters will be the maximal ankle plantarflexion angle, ankle angular velocity and knee flexion angle during the loading response, which will be measured using a 3D gait analysis. Secondary outcomes include other gait biomechanics, walking energy cost, walking speed, standing balance, perceived physical functioning and perceived walking ability.

Study Overview

• Status: Not yet recruiting
• Conditions: Neuromuscular Disorders
• Intervention / Treatment: Device: NEURO SWING AFO (Fior& Gentz, Lüneburg In Duderstadt, Germany); Device: WalkOn Reaction® (Ottobock, Duderstadt); Device: Matrix Max2® (TruLife, Dublin, Ireland); Device: Matrix® (TruLife, Dublin, Ireland)

Detailed Description

Many neuromuscular diseases cause weakness of the ankle dorsiflexors and plantarflexors, resulting in an altered gait pattern. In particular, weakness of the plantar flexors leads to a reduced walking ability as it hampers safety in both standing and walking. The primary treatment to improve walking ability and safety during standing and walking in dorsiflexor and/or plantarflexor weakness is the provision of ankle-foot orthoses (AFOs). To maximize treatment outcomes in case of lower leg weakness, the optimal AFO stiffness needs to be individually determined. Individual optimization of the stiffness can be performed with a spring-like AFO or with a spring-hinged AFO. With a spring-like AFO, the stiffness towards plantar- and dorsiflexion is similar, oftentimes resulting in a higher than necessary stiffness towards plantarflexion. An advantage of spring-hinged AFOs is that, unlike spring-like AFOs, the stiffness can be separately optimized in the directions of dorsiflexion and plantarflexion.

The objective of this pilot study is to evaluate the effects of separate individualization of the AFO stiffness towards plantar- and dorsiflexion in a spring-hinged AFO compared to three types of spring-like AFO having the same stiffness in both directions on gait biomechanics, walking energy cost, walking speed, and standing balance. Additionally, effects will be evaluated of the optimal spring-hinged AFO 6 weeks after delivery of the AFO on perceived physical functioning, walking ability and satisfaction in daily life compared to the participants' AFO used at baseline if applicable or walking with shoes-only.

In this pilot study with a pre-post design, people with a neuromuscular disease or nerve injury causing at least plantarflexor weakness with an indication for or using an AFO will be fitted with a new, custom-made spring-hinged AFO with the NEURO SWING® system ankle joint (Fior& Gentz, Lüneburg In Duderstadt, Germany). The stiffness of ventral and dorsal compartment of this spring-hinged AFO will be individualized using a previously developed optimization algorithm. The spring-hinged AFO with optimal stiffness settings will be used at home for 6-weeks. For comparison, the investigators will test the direct effects of three different prefab spring-like AFOs with different stiffness levels (but which have a similar stiffness towards plantar and dorsiflexion) of 2.8, 1.4 and 0.6 Nm/degrees respectively in a randomized order, and the participants' current AFO if applicable, and shoes-only at baseline.

• Study Type: Interventional
• Enrollment (Estimated): 10
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Merel-Anne Brehm, PhD; Phone Number: + 3120 5664049; Email: m.a.brehm@amsterdamumc.nl
• Study Contact Backup: Name: Elza van Duijnhoven; Phone Number: +3120 5666915; Email: e.vanduijnhoven@amsterdamumc.nl

Study Locations

• Netherlands
  • Amsterdam, Netherlands, 1105AZ
    • Department of rehabilitation medicine Amsterdam UMC, location AMC

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Age 18 years or older;
2. Presence of plantar flexor weakness in at least one leg, determined as a score lower than 5 on the manual muscle testing scale (Medical Research Council- MRC) and/or inability to perform three single heel rises, with or without dorsiflexion weakness;
3. Indicated for or using an AFO;
4. Ability to walk 6-minutes consecutively (with assistive device, if necessary).

Exclusion Criteria:

1. When wearing the AFO, not able to walk short bouts of 10m without walking aids, such as a walker;
2. Foot deformities that do not fit in prefab spring-like AFOs;
3. Weakness of the knee extensor muscles, for which a knee-ankle-foot orthosis is indicated.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: NEURO SWING AFO; Participants will be fitted with a new custom-made spring-hinged AFO with the NEURO SWING® system ankle joint. Following a previously developed algorithm, the stiffness will be individually selected from six different configurations tested during an optimization measurement directly after delivery of the new AFO. Thereafter, participants will use the optimized AFO with individualized stiffness at home for six weeks during the course of the study.

Device: NEURO SWING AFO (Fior& Gentz, Lüneburg In Duderstadt, Germany); stiffness-optimized custom-made spring-hinged AFO with the NEURO SWING® system ankle joint build in; Device: WalkOn Reaction® (Ottobock, Duderstadt); comparator: prefab spring-like AFO without hinge with a predefined stiffness (2.8 Nm/degree).; Device: Matrix Max2® (TruLife, Dublin, Ireland); comparator: prefab spring-like AFO without hinge with a predefined stiffness (1.4 Nm/degree); Device: Matrix® (TruLife, Dublin, Ireland); comparator: prefab spring-like AFO without hinge with a predefined stiffness (0.6 Nm/degree)

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
maximal ankle angular velocity in loading response in degrees	measured during a 3D gait analysis	day 0 (directly post-delivery)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
maximal ankle angular velocity in loading response	measured during a 3D gait analysis	6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO
minimal ankle angle in loading response in degrees	measured during a 3D gait analysis	day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
ankle angle during midstance in degrees	measured during a 3D gait analysis	day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
maximal ankle angle during the stance phase in degrees	measured during a 3D gait analysis	day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
maximal ankle moment in Nm/kg	measured during a 3D gait analysis	day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
maximal ankle push-off power in Watt/kg	measured during a 3D gait analysis	day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
maximal knee flexion angle in loading response in degrees	measured during a 3D gait analysis	day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
minimal knee flexion angle during the stance phase in degrees	measured during a 3D gait analysis	day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
maximal external knee flexion moment in loading response in degrees	measured during a 3D gait analysis	day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
minimal external knee flexion moment during the stance phase in Nm/kg	measured during a 3D gait analysis	day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
maximal hip power during loading response in Watt/kg	measured during a 3D gait analysis	day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
maximal hip power during ankle push-off in Watt/kg	measured during a 3D gait analysis	day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
walking speed in m/s	Walking speed will be measured during a 6-minute walk test (6MWT) at a self-selected comfortable speed.	day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
walking energy cost in J/kg/m	During a 6-minute walk test (6MWT) at comfortable speed, oxygen uptake (VO2) and carbon dioxide production (VCO2) will be measured using a breath-by-breath gas analysis system (K5, Cosmed, Rome, Italy) worn on the patient's back. Over at least one minute during the last three minutes of the test, walking energy cost will be calculated from these measured parameters and the comfortable walking speed.	day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
velocity of center-of-pressure displacement in mm/s	During the 3D gait analysis, a standing balance test will be performed. Participants will stand on one force plate with a standardised distance of 10 cm between the medial borders of the feet for 30 seconds. Standing posture, in terms of joint angles, will be determined using the markers placed according to the Plug-in-Gait model. Postural sway will be calculated as the Center-of-Pressure displacement during the last 15 seconds of the test.	day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
center-of-pressure displacement in mm	During the 3D gait analysis, a standing balance test will be performed. Participants will stand on one force plate with a standardised distance of 10 cm between the medial borders of the feet for 30 seconds. Standing posture, in terms of joint angles, will be determined using the markers placed according to the Plug-in-Gait model. Postural sway will be calculated as the Center-of-Pressure displacement during the last 15 seconds of the test.	day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
Perceived walking ability	Perceived walking ability in terms of satisfaction, intensity, safety and stability during walking will be measured on a 10-point Numerical Rating Scale (NRS) ranging from 0 (worst possible score) to 10 (best possible score).	baseline and 6 weeks post-delivery of the stiffness-optimized NEURO SWING AFO
Perceived physical functioning	Physical functioning will be measured using the physical functioning scale of the 36-item short form health survey (SF-36), with range 0-100 (a higher score means a better functioning).	baseline and 6 weeks post-delivery of the stiffness-optimized NEURO SWING AFO

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
number of participants with adverse events	Adverse events are defined as any undesirable experience occurring to a subject during the study, whether or not considered related to the investigational product or experiments. The following adverse events reported spontaneously by the subject or observed by the investigator or his staff will be recorded; pressure sores, muscle soreness, pain, and falls.	from baseline to 6 weeks post-delivery of the stiffness-optimized NEURO SWING AFO

Collaborators and Investigators

• Sponsor: Academisch Medisch Centrum - Universiteit van Amsterdam (AMC-UvA)
• Collaborators: FIOR & GENTZ
• Investigators: Study Director: Frans Nollet, MD PhD, Amsterdam UMC, location AMC

Study record dates

Study Major Dates

• Study Start (Estimated): May 5, 2024
• Primary Completion (Estimated): February 1, 2025
• Study Completion (Estimated): February 1, 2025

Study Registration Dates

• First Submitted: May 2, 2024
• First Submitted That Met QC Criteria: May 13, 2024
• First Posted (Actual): May 14, 2024

Study Record Updates

• Last Update Posted (Actual): May 14, 2024
• Last Update Submitted That Met QC Criteria: May 13, 2024
• Last Verified: May 1, 2024

More Information

Terms related to this study

• Keywords: Neuromuscular disorders; dorsiflexor and plantarflexor weakness; ankle-foot orthosis (AFO); bidirectional stiffness tuning; Gait kinetics and kinematics; Walking energy cost; Perceived physical functioning
• Additional Relevant MeSH Terms: Nervous System Diseases; Neuromuscular Diseases
• Other Study ID Numbers: NL85684.018.23

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Anonymized individual participant data (IPD) and meta data will be made available to third parties via Figshare. Other anonymized IPD and documents will be made available on request including data analyses codes such as SPSS syntaxes.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No