Augmenting Ankle Plantarflexor Function in Cerebral Palsy

Augmenting Ankle Plantarflexor Function and Walking Capacity in Children With Cerebral Palsy

The first specific aim is to quantify improvement in ankle muscle function and functional mobility following targeted ankle resistance gait training in ambulatory children with cerebral palsy (CP). The primary hypothesis for the first aim is that targeted ankle resistance training will produce larger improvements in lower-extremity motor control, gait mechanics, and clinical measures of mobility assessed four- and twelve-weeks post intervention compared to standard physical therapy and standard gait training. The second specific aim is to determine the efficacy of adaptive ankle assistance to improve capacity and performance during sustained, high-intensity, and challenging tasks in ambulatory children with CP. The primary hypothesis for the second aim is that adaptive ankle assistance will result in significantly greater capacity and performance during the six-minute-walk-test and graded treadmill and stair stepping protocols compared to walking with ankle foot orthoses and walking with just shoes.

Study Overview

• Status: Recruiting
• Conditions: Cerebral Palsy
• Intervention / Treatment: Device: Biomotum Spark: Robotic ankle resistance; Other: Standard gait training; Other: Standard physical therapy; Device: Biomotum Spark: Robotic ankle assistance; Device: Ankle foot orthosis; Other: Standard walking

Detailed Description

A child's ability to walk effectively is essential to their physical health and general well-being. Unfortunately, many children with cerebral palsy (CP), the most common cause of pediatric physical disability, have difficulty walking and completing higher-intensity ambulatory tasks. This leads to children with CP engaging in levels of habitual physical activity that are well below guidelines and those of children without disabilities, which in turn contributes to many secondary conditions, including metabolic dysfunction and cardiovascular disease. There is broad clinical consensus that plantarflexor dysfunction is a primary contributor to slow, inefficient, and crouched walking patterns in CP; individuals with CP need more effective treatments and mobility aids for plantarflexor dysfunction. To meet this need, this proposal aims to evaluate a holistic strategy to address impaired mobility from plantarflexor dysfunction in CP using a lightweight, dual-mode (assistive or resistive) wearable robotic device. This strategy combines two complementary techniques: (1) targeted ankle resistance for neuromuscular gait training that provides precision therapy to elicit long-term improvements in ankle muscle function, and (2) adaptive ankle assistance to make walking easier during sustained, high-intensity, or challenging tasks.

Aim 1: Quantify improvement in ankle muscle function and functional mobility following targeted ankle resistance gait training in ambulatory children with CP Approach - Repeated Measures (RM) and randomized controlled trial: The investigators will compare functional outcomes following targeted ankle resistance training (2 visits/week for 12 weeks) vs. dose-matched standard physical therapy (RM) and vs. dose-matched standard treadmill training (randomized controlled trial). Primary Hypothesis: Targeted ankle resistance training will produce larger improvements in lower-extremity motor control, gait mechanics, and clinical measures of mobility assessed four- and twelve-weeks post intervention compared to the control conditions.

Aim 2: Determine the efficacy of adaptive ankle assistance to improve capacity and performance during sustained, high-intensity, and challenging tasks in ambulatory children with CP Approach - Repeated Measures: The investigators will compare task capacity and performance with adaptive ankle assistance vs. standard ankle foot orthoses and vs. shod (no ankle aid) during (a) 6-minute-walk-test, (b) extended-duration over-ground walking (sustained), (c) graded treadmill (high-intensity), and (d) stair-stepping (challenging) protocols. Task capacity and performance will be measured by duration, metabolic cost, speed, and stride length, as applicable. Primary Hypothesis: Adaptive ankle assistance will result in significantly greater capacity and performance compared to the control conditions.

• Study Type: Interventional
• Enrollment (Estimated): 36
• Phase: Phase 1

Contacts and Locations

• Study Contact: Name: Zach Lerner, PhD; Phone Number: 928-523-1787; Email: zachary.lerner@nau.edu

Study Locations

• United States
  • Minnesota
    • Minneapolis, Minnesota, United States, 55101
      • Recruiting
      • Gillette Children's Specialty Healthcare
      • Contact: Mike Schwartz, PhD; Phone Number: 651-229-3929; Email: MSchwartz@gillettechildrens.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 8 years to 18 years (Child, Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Ages between 8 and 21 years old, inclusive. Diagnosis of CP and a pathological gait pattern caused by ankle dysfunction.
• Able to understand and follow simple directions (based on parent report, if needed) and walk at least 30 feet with or without a walking aid (Gross Motor Function Classification System (GMFCS) Level I-III).
• At least 20° of passive plantar-flexion range of motion.

Exclusion Criteria:

• Concurrent treatment other than those assigned during the study.
• A condition other than CP that would affect safe participation.
• Surgical intervention within 6 months of participation.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

6

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Device resisted gait training (treatment); We will conduct a randomized controlled trial (treatment vs. control) to compare functional outcomes following bilateral targeted ankle resistance training (2 visits/week for 12 weeks) vs. dose-matched standard functional gait training.	Device: Biomotum Spark: Robotic ankle resistance; A lightweight resistive wearable ankle robotic device.
Experimental: Standard gait training (control); We will conduct a randomized controlled trial (treatment vs. control) to compare functional outcomes following bilateral targeted ankle resistance training (2 visits/week for 12 weeks) vs. dose-matched standard functional gait training.	Other: Standard gait training; Standard gait training without a device.
Experimental: Comparison to Standard PT (within subjects control); We will use a within-subject repeated measures design to compare both gait training groups to matched standard physical therapy.	Other: Standard physical therapy; Physical therapy without a device.
Experimental: Device assisted ambulation; We will compare task capacity and performance with adaptive ankle assistance vs. standard ankle foot orthoses and vs. shod (no ankle aid).	Device: Biomotum Spark: Robotic ankle assistance; A lightweight assistive wearable ankle robotic device.
Experimental: Passive brace assisted ambulation; We will compare task capacity and performance with adaptive ankle assistance vs. standard ankle foot orthoses and vs. shod (no ankle aid).	Device: Ankle foot orthosis; Standard ankle foot orthosis
Experimental: No ankle aid ambulation; We will compare task capacity and performance with adaptive ankle assistance vs. standard ankle foot orthoses and vs. shod (no ankle aid).	Other: Standard walking; Walking without a device

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in preferred walking speed	Participant's preferred walking speed compared after to before the intervention	Immediately after the intervention
Change in preferred walking speed	Participant's preferred walking speed compared after to before the intervention	2 weeks after the intervention
Change in preferred walking speed	Participant's preferred walking speed compared after to before the intervention	12 weeks after the intervention
Change in similarity of plantarflexor muscle activity	Similarity of the plantarflexor muscle activity profile across the gait cycle, measured using surface electromyography (the measurement tool) of the soleus muscle, to the average unimpaired electromyography muscle activity profile, as calculated via cross-correlation coefficient. A higher value indicates greater similarity.	Immediately after the intervention
Change in similarity of plantarflexor muscle activity	Similarity of the plantarflexor muscle activity profile across the gait cycle, measured using surface electromyography (the measurement tool) of the soleus muscle, to the average unimpaired electromyography muscle activity profile, as calculated via cross-correlation coefficient. A higher value indicates greater similarity.	2 weeks after the intervention
Change in similarity of plantarflexor muscle activity	Similarity of the plantarflexor muscle activity profile across the gait cycle, measured using surface electromyography (the measurement tool) of the soleus muscle, to the average unimpaired electromyography muscle activity profile, as calculated via cross-correlation coefficient. A higher value indicates greater similarity.	12 weeks after the intervention
Change in 6-minute-walk-test distance	Distance traveled in 6 minutes during a 6-minute-walk-test protocol. A longer distance indicates greater walking capacity.	Immediately after the intervention
Change in 6-minute-walk-test distance	Distance traveled in 6 minutes during a 6-minute-walk-test protocol. A longer distance indicates greater walking capacity.	2 weeks after the intervention
Change in 6-minute-walk-test distance	Distance traveled in 6 minutes during a 6-minute-walk-test protocol. A longer distance indicates greater walking capacity.	12 weeks after the intervention
Change in variance in muscle activity	Variance in muscle activity accounted for by one muscle synergy assessed using surface electromyography (the measurement tool) of the soleus, tibialis anterior, medial hamstrings, and vastus medialis. Muscle synergies will be computed from non-negative matrix factorization. Lower variance accounted for by one muscle synergy indicates a desired greater complexity of motor control.	Immediately after the intervention
Change in variance in muscle activity	Variance in muscle activity accounted for by one muscle synergy assessed using surface electromyography (the measurement tool) of the soleus, tibialis anterior, medial hamstrings, and vastus medialis. Muscle synergies will be computed from non-negative matrix factorization. Lower variance accounted for by one muscle synergy indicates a desired greater complexity of motor control.	2 weeks after the intervention
Change in variance in muscle activity	Variance in muscle activity accounted for by one muscle synergy assessed using surface electromyography (the measurement tool) of the soleus, tibialis anterior, medial hamstrings, and vastus medialis. Muscle synergies will be computed from non-negative matrix factorization. Lower variance accounted for by one muscle synergy indicates a desired greater complexity of motor control.	12 weeks after the intervention
Change in stride length	Participant stride length during walking. Longer stride length is desired.	Immediately after the intervention
Change in stride length	Participant stride length during walking. Longer stride length is desired.	2 weeks after the intervention
Change in stride length	Participant stride length during walking. Longer stride length is desired.	12 weeks after the intervention
Change in stride-to-stride variability stride length	Stride-to-stride variability of lower-extremity muscle activity for the soleus, tibias anterior, vastus lateralis, and medial hamstrings, measured via surface electromyography and calculated as the variance ratio across strides.	Immediately after the intervention
Change in stride-to-stride variability stride length	Stride-to-stride variability of lower-extremity muscle activity for the soleus, tibias anterior, vastus lateralis, and medial hamstrings, measured via surface electromyography and calculated as the variance ratio across strides.	2 weeks after the intervention
Change in stride-to-stride variability stride length	Stride-to-stride variability of lower-extremity muscle activity for the soleus, tibias anterior, vastus lateralis, and medial hamstrings, measured via surface electromyography and calculated as the variance ratio across strides.	12 weeks after the intervention
Change in walking posture	Peak Lower-extremity joint angles summed across the ankle, knee, and hip joints, measured using motion capture (the measurement tool).	Immediately after the intervention
Change in walking posture	Peak Lower-extremity joint angles summed across the ankle, knee, and hip joints, measured using motion capture (the measurement tool).	2 weeks after the intervention
Change in walking posture	Peak Lower-extremity joint angles summed across the ankle, knee, and hip joints, measured using motion capture (the measurement tool).	12 weeks after the intervention
Change in Gross Motor Function Measure-66 sec. D&E	Gross Motor Function Measure - 66, sections (D) standing, and (E) walking, running and jumping. Higher scores are better, and range from 0-3 for each measure.	Immediately after the intervention
Change in Gross Motor Function Measure-66 sec. D&E	Gross Motor Function Measure - 66, sections (D) standing, and (E) walking, running and jumping. Higher scores are better, and range from 0-3 for each measure.	2 weeks after the intervention
Change in Gross Motor Function Measure-66 sec. D&E	Gross Motor Function Measure - 66, sections (D) standing, and (E) walking, running and jumping. Higher scores are better, and range from 0-3 for each measure.	12 weeks after the intervention
Change in plantar-flexor strength	Plantar-flexor muscle strength measured via hand-held dynamometry.	Immediately after the intervention
Change in plantar-flexor strength	Plantar-flexor muscle strength measured via hand-held dynamometry.	2 weeks after the intervention
Change in plantar-flexor strength	Plantar-flexor muscle strength measured via hand-held dynamometry.	12 weeks after the intervention
Distance traveled	Distance traveled during the 6-minute-walk-test, and treadmill and stair stepper bruce protocols.	1 day
Metabolic cost of transport from indirect calorimetry	Metabolic cost estimated from a wearable indirect calorimetry system during the 6-minute-walk-test, and treadmill and stair stepper bruce protocols	1 day
Subject perceived exertion	Subject perceived exertion (validated pictorial pediatric exertion scale). The scale is from 1-10, where a higher number indicates more effort.	1 day
Average muscle activity	Average stance-phase plantar flexor muscle activity assessed through surface electromyography of the soleus muscle.	1 day
Heart Rate	Average heart rate during each testing condition measured via chest-mounted heart rate monitor.	1 day

Collaborators and Investigators

• Sponsor: Northern Arizona University
• Collaborators: University of Washington; Gillette Children's Specialty Healthcare
• Investigators: Principal Investigator: Zach F Lerner, PhD, Northern Arizona University

Study record dates

Study Major Dates

• Study Start (Actual): February 1, 2023
• Primary Completion (Estimated): September 14, 2026
• Study Completion (Estimated): September 25, 2026

Study Registration Dates

• First Submitted: October 13, 2021
• First Submitted That Met QC Criteria: November 30, 2021
• First Posted (Actual): December 13, 2021

Study Record Updates

• Last Update Posted (Actual): March 3, 2026
• Last Update Submitted That Met QC Criteria: February 27, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: Rehabilitation; Gait
• Additional Relevant MeSH Terms: Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Brain Damage, Chronic; Cerebral Palsy
• Other Study ID Numbers: 1R01HD107277 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: No