Clinical trial NCT06412055: Bidirectional Tuning of the AFO Stiffness
Official title: Optimizing Gait with Bidirectional Tuning of the Ankle-foot Orthosis (AFO) Stiffness in People with Lower Leg Muscle Weakness
Study type: INTERVENTIONAL
Overall status: RECRUITING
Phase: NA
Conditions: Neuromuscular Disorders
Keywords: Neuromuscular disorders
dorsiflexor and plantarflexor weakness
ankle-foot orthosis (AFO)
bidirectional stiffness tuning
Gait kinetics and kinematics
Walking energy cost
Perceived physical functioning
Lead sponsor: Academisch Medisch Centrum - Universiteit van Amsterdam (AMC-UvA)
Sponsor class: OTHER
Collaborators: name: FIOR & GENTZ
First posted: 2024-05-14
Enrollment: 10
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: NA
Intervention model: SINGLE_GROUP
Intervention model description: pilot self-controlled intervention study with measurements of three spring-like AFOs (WalkOn Reaction® (Ottobock, Duderstadt), the Matrix Max2® (TruLife, Dublin, Ireland), and the Matrix® (TruLife, Dublin, Ireland)) having the same stiffness in both directions, and a newly custom-made spring-hinged AFO with the NEURO SWING® system ankle joint with individualized spring settings (Fior\& Gentz, Lüneburg, Germany) directly after delivery and 6 weeks post-delivery.
Primary purpose: TREATMENT

Brief summary: 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, 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.

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, 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.

Eligibility criteria: 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.

Primary outcomes:
measure: maximal ankle angular velocity in loading response in degrees
timeFrame: day 0 (directly post-delivery)
Secondary outcomes:
measure: maximal ankle angular velocity in loading response
timeFrame: 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO
measure: minimal ankle angle in loading response in degrees
timeFrame: day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
measure: ankle angle during midstance in degrees
timeFrame: day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
measure: maximal ankle angle during the stance phase in degrees
timeFrame: day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
measure: maximal ankle moment in Nm/kg
timeFrame: day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
measure: maximal ankle push-off power in Watt/kg
timeFrame: day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
measure: maximal knee flexion angle in loading response in degrees
timeFrame: day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
measure: minimal knee flexion angle during the stance phase in degrees
timeFrame: day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
measure: maximal external knee flexion moment in loading response in degrees
timeFrame: day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
measure: minimal external knee flexion moment during the stance phase in Nm/kg
timeFrame: day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
measure: maximal hip power during loading response in Watt/kg
timeFrame: day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
measure: maximal hip power during ankle push-off in Watt/kg
timeFrame: day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
measure: walking speed in m/s
timeFrame: day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
measure: walking energy cost in J/kg/m
timeFrame: day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
measure: velocity of center-of-pressure displacement in mm/s
timeFrame: day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
measure: center-of-pressure displacement in mm
timeFrame: day 0 (directly post-delivery) and 6 weeks post-delivery for the stiffness-optimized NEURO SWING AFO only
measure: Perceived walking ability
timeFrame: baseline and 6 weeks post-delivery of the stiffness-optimized NEURO SWING AFO
measure: Perceived physical functioning
timeFrame: baseline and 6 weeks post-delivery of the stiffness-optimized NEURO SWING AFO
Other outcomes:
measure: number of participants with adverse events
timeFrame: from baseline to 6 weeks post-delivery of the stiffness-optimized NEURO SWING AFO
Locations:
city: Amsterdam
country: Netherlands
facility: Department of rehabilitation medicine Amsterdam UMC, location AMC
Study officials:
affiliation: Amsterdam UMC, location AMC
name: Frans Nollet, MD PhD
role: STUDY_DIRECTOR
References: