Biomechanics

CR DeVol, SR Shrivastav, VM Landrum, KF Bjornson, D Roge, CT Moritz, KM Steele (2025) “Effects of spinal stimulation and short-burst treadmill training on gait biomechanics in children with cerebral palsy”

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Journal article in Gait & Posture

Children with cerebral palsy (CP) have an injury to the central nervous system around the time of birth that affects the development of the brain and spinal cord. This injury leads to changes in gait neuromechanics, including muscle activity and joint kinematics. Transcutaneous spinal cord stimulation (tSCS) is a novel neuromodulation technique that may improve movement and coordination in children with CP when paired with targeted physical therapy.

Example kinematics and muscles activity at each assessment timepoint for P03’s more-affected side. A) Sagittal-plane hip, knee, and ankle kinematics over the gait cycle. Horizontal colored lines indicate where there were significant changes in kinematics over each phase of the study based on statistical parametric mapping (p Aim: How does the combination of tSCS and short-burst interval locomotor treadmill training (SBLTT) affect individual gait neuromechanics in children with CP?

Methods: Four children with CP (4–13 years old), received 24 sessions each of SBLTT only and SBLTT with tSCS (tSCS+SBLTT). Clinical assessments of spasticity and passive range of motion (PROM), as well as biomechanical assessments of joint kinematics, musculotendon lengths, and muscle activity were recorded during overground, barefoot walking. Assessments were taken before and after each intervention, and 8-weeks later.

Results: The combination of tSCS+SBLTT led to greater increases in hip and knee extension than SBLTT only for three participants. Three children also became more plantarflexed at the ankle during stance after tSCS+SBLTT compared to SBLTT only. While tSCS+SBLTT reduced spasticity, these changes were only weakly correlated with changes in musculotendon lengths during gait or PROM, with the largest correlation between change in gastrocnemius operating musculotendon length during fast walking and gastrocnemius spasticity (R2 = 0.26) and change in plantarflexor PROM and gastrocnemius spasticity (R2 = 0.23).

Interpretation: Children with CP used a more upright, less crouched posture during gait after tSCS+SBLTT. Large reductions in spasticity after tSCS+SBLTT were only weakly correlated with changes in kinematics and PROM. Understanding the mechanisms by which tSCS may affect gait for children with CP is critical to optimize and inform the use of tSCS for clinical care.

CR DeVol, SR Shrivastav, AM Spomer, KF Bjornson, D Roge, CT Moritz, KM Steele (2024) “Effects of interval treadmill training on spatiotemporal parameters in children with cerebral palsy: A machine learning approach”

Katie Landwehr JournalArticle, Publications , , , ,

Journal Article in Journal of Biomechanics

Quantifying individualized rehabilitation responses and optimizing therapy for each person is challenging. For interventions like treadmill training, there are multiple parameters, such as speed or incline, that can be adjusted throughout sessions.

A) Pre-post effect of SBLTT on step length for the more affected side. B) BART results quantify direct effects of SBLTT on step length. Accumulated Local Effects (ALE) plots for each input variable show the effect of that variable on step length including session number, treadmill speed (Froude number), time within session, side, and treadmill incline. The size of the data point on each ALE plot depicts the relative number of data points in each bin. C) BART model fit (R2) for each participant. D) Direct effects of each input variable on the response variable, step length, calculated from the change in the ALE plots in B).Aim: This study evaluates if causal modeling and Bayesian Additive Regression Trees (BART) can be used to accurately track the direct effects of treadmill training on gait.

Methods: We developed a Directed Acyclic Graph (DAG) to specify the assumed relationship between training input parameters and spatiotemporal outcomes during Short Burst Locomotor Treadmill Training (SBLTT), a therapy designed specifically for children with cerebral palsy (CP). We evaluated outcomes after 24 sessions of SBLTT for simulated datasets of 150 virtual participants and experimental data from four children with CP, ages 4–13 years old. Individual BART models were created from treadmill data of each step.

Results: Simulated datasets demonstrated that BART could accurately identify specified responses to training, including strong correlations for step length progression (R2 = 0.73) and plateaus (R2 = 0.87). Model fit was stronger for participants with less step-to-step variability but did not impact model accuracy. For experimental data, participants’ step lengths increased by 26 ± 13 % after 24 sessions. Using BART to control for speed or incline, we found that step length increased for three participants (direct effect: 13.5 ± 4.5 %), while one participant decreased step length (−11.6 %). SBLTT had minimal effects on step length asymmetry and step width.

Interpretation: Tools such as BART can leverage step-by-step data collected during training for researchers and clinicians to monitor progression, optimize rehabilitation protocols, and inform the causal mechanisms driving individual responses.

National Biomechanics Day 2024

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Last week the Steele Lab celebrated National Biomechanics Day (NBD) on April 3, 2024 at the VA Puget Sound. Mia Hoffman, Sasha Portnova, and Katie Landwehr, alongside fellow Biomechanics researchers with the Ingraham Lab, and Center for Limb Loss and MoBility (CLiMB) hosted over 75 students from a local high school.

A group of five people posing for a photo

NBD is a world-wide celebration of Biomechanics in its many forms for high school students and teachers. Steele Lab PhD student Mia Hoffman, and Ingraham Lab PhD student Annika Pfister were recently awarded a $1000 grant from the American Society of Biomechanics and National Biomechanics Day to host an outreach event for high school students focused on disability biomechanics.

Mia and Katie hosted a station on “Switch-Adapted Toys & Accessible Design”

Two women (Mia and Katie) standing in front of a wall with pictures and holding adaptive toys and DIY switches.
A group of people standing around a table of DIY switches and switch adapted toys
A group of people standing around a table of DIY switches and playing games on an iPad

Sasha, Annika, and Zijie hosted a station on “Myodino: Activate your Muscles”

A group of people holding a sign that says "MyoDino Scoreboard"
A group of people standing around a table with computers. One person is wearing an EMG sensor on their forearm
A group of people standing around a table with computers. One person is wearing an EMG sensor on their forearm