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.
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.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
TREATMENT
Masking
NONE
Enrollment
10
stiffness-optimized custom-made spring-hinged AFO with the NEURO SWING® system ankle joint build in
comparator: prefab spring-like AFO without hinge with a predefined stiffness (2.8 Nm/degree).
comparator: prefab spring-like AFO without hinge with a predefined stiffness (1.4 Nm/degree)
comparator: prefab spring-like AFO without hinge with a predefined stiffness (0.6 Nm/degree)
Department of rehabilitation medicine Amsterdam UMC, location AMC
Amsterdam, Netherlands
RECRUITINGmaximal ankle angular velocity in loading response in degrees
measured during a 3D gait analysis
Time frame: day 0 (directly post-delivery)
maximal ankle angular velocity in loading response
measured during a 3D gait analysis
Time frame: 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
Time frame: 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
Time frame: 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
Time frame: 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
Time frame: 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
Time frame: 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
Time frame: 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
Time frame: 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
Time frame: 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
Time frame: 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
Time frame: 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
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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).
Time frame: 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).
Time frame: baseline and 6 weeks post-delivery of the stiffness-optimized NEURO SWING AFO
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