Augmenting Ankle Plantarflexor Function in Cerebral Palsy

Study Overview
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Brief Summary
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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.

Detailed Description
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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.

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

Conditions
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Cerebral Palsy

Intervention / Treatment
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* Device: Biomotum Spark: Robotic ankle assistance
* Device: Biomotum Spark: Robotic ankle resistance
* Other: Standard gait training
* Device: Ankle foot orthosis
* Other: Standard physical therapy
* Other: Standard walking


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Ages between 8 and 18 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.

Ages Eligible for Study
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Minimum Age: 8 Years
Maximum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

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


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Device resisted gait training (treatment)<br>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<br>* A lightweight resistive wearable ankle robotic device.<br>|
| Experimental: Standard gait training (control)<br>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<br>* Standard gait training without a device.<br>|
| Experimental: Comparison to Standard PT (within subjects control)<br>We will use a within-subject repeated measures design to compare both gait training groups to matched standard physical therapy. | Other: Standard physical therapy<br>* Physical therapy without a device.<br>|
| Experimental: Device assisted ambulation<br>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<br>* A lightweight assistive wearable ankle robotic device.<br>|
| Experimental: Passive brace assisted ambulation<br>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<br>* Standard ankle foot orthosis<br>|
| Experimental: No ankle aid ambulation<br>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<br>* Walking without a device<br>|

What is the study measuring?
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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 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Gait, Rehabilitation