Projects

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”

Katie Landwehr JournalArticle, News, SpinalStim , , , , , , , , , ,

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.

APTA CSM 2025 Conference Recap

Katie Landwehr EarlyMobility, News, Presentation , , , ,

Neuromechanics & Mobility Lab member, Mia Hoffman, attended the 50th Annual American Physical Therapy Association Combined Sections Meeting (APTA CSM) in Houston, TX on Feb 13-15, where thousands of PTs, PTAs, and students came together to learn, connect, and celebrate 50 years of innovation in physical therapy.

Mia, alongside IMPACT Collaboratory members Heather A. Feldner, PT, MPT, PhD and Tiffany Li, SPT, presented a workshop on “Co-Designing a Switch Accessible Digital Play Environment for Children in Partnership with Clinicians and Families“.

Three women stand together at a conference center. The women in the center is holding a bag containing the "switch kit" supplies.

KA Ingraham, NL Zaino, C Feddema, ME Hoffman, L Gijbels, A Sinclair, AN Meltzoff, PK Kuhl, HA Feldner, KM Steele (2025) “Quantifying Joystick Interactions and Movement Patterns of Toddlers With Disabilities Using Powered Mobility With an Instrumented Explorer Mini”

Katie Landwehr EarlyMobility, JournalArticle, News, Publications , , , , ,

Journal Article in IEEE Transactions on Neural Systems and Rehabilitation Engineering

Powered mobility technology can be a powerful tool to facilitate self-initiated exploration and play for toddlers with motor disabilities. The joystick-controlled Permobil Explorer Mini is currently the only commercially available powered mobility device for children ages 1-3 years in the United States. However, many open questions persist regarding how joystick-based mobility technologies should be designed to optimally suit the developmental needs of toddlers.

The instrumented Explorer Mini measures joystick position in (x,y) coordinates and the number of wheel rotations for the left and right wheels at a sampling frequency of 100 Hz. Wheel displacement is calculated by multiplying the number of rotations by the measured wheel circumference. Representative raw data collected from the device are shown here for 100 seconds.Aim: The purpose of this study was to quantify how toddlers with motor disabilities use the Explorer Mini during free exploration and play.

Methods: For this work, we developed a custom-instrumented Explorer Mini with embedded sensors to measure joystick interactions and wheel rotations. Nine children with motor disabilities (ages 12-36 months) participated in 12 in-lab visits, and during each visit they engaged in two 15-20 minute play sessions. For each session, we calculated several quantitative outcome metrics, including the time spent using the joystick, distance traveled, and the number, duration, and complexity of joystick interactions.

Results: Every participant independently interacted with the joystick and moved the Explorer Mini during every session. Over 12 visits, participants significantly increased their distance traveled and the time spent with the joystick active. Surprisingly, we found that only 48% of joystick interactions resulted in device movement, which has important implications for learning.

Interpretation: These results can serve as a benchmark for caregivers and clinicians to understand early device use patterns. Furthermore, this knowledge can be used to inform the design of new powered mobility technologies for toddlers with disabilities or support the refinement of existing devices.

SR Shrivastav, CR DeVol, VM Landrum, KF Bjornson, D Roge, KM Steele, CT Moritz (2024) “Transcutaneous Spinal Stimulation and Short-burst Interval Treadmill Training in Children with Cerebral Palsy: A Pilot Study”

Katie Landwehr JournalArticle, News, Publications, SpinalStim , , ,

Journal Article in IEEE Transactions on Biomedical Engineering

Non-invasive neuromodulation may be an alternative approach that can improve outcomes in CP when combined with physical therapy. Transcutaneous spinal cord stimulation (tSCS) is a novel, non-invasive neuromodulation technique that can modulate spinal and supraspinal circuits especially when implemented with physical therapy.

A) Short-burst interval locomotor treadmill training (SBLTT) with contact guard assist. B) Investigative spinal cord neuromodulation device (SpineX, Inc.) with stimulating electrodes on the T11 and L1 dorsal spinous processes and two ground electrodes on the anterior superior iliac spine (ASIS - not visible). C) Spinal stimulation waveform with 10 kHz carrier frequency. D) Protocol timeline including the assessments before and after each intervention and after 8-weeks of follow-up. tSCS = transcutaneous spinal cord stimulationAim: The purpose of this pilot study was to evaluate the effects of transcutaneous spinal cord stimulation (tSCS) and short-burst interval locomotor treadmill training (SBLTT) on spasticity and mobility in children with cerebral palsy (CP).

Methods: We employed a single-arm design with two interventions: SBLTT only, and tSCS + SBLTT, in four children with CP. Children received 24-sessions each of SBLTT only and tSCS + SBLTT. Spasticity, neuromuscular coordination, and walking function were evaluated before, immediately after, and 8- weeks following each intervention.

Results: Spasticity, measured via the Modified Ashworth Scale (MAS), reduced in four lower extremity muscles after tSCS + SBLTT (1.40 ± 0.22,) more than following SBLTT only (0.43 ± 0.39). One-minute walk test (1-MWT) distance was maintained during both interventions. tSCS + SBLTT led to improvements in peak hip and knee peak extension (4.9 ± 7.3° and 6.5 ± 7.7°), that drove increases in joint dynamic range of 4.3 ± 2.4° and 3.8 ± 8.7° at the hip and knee, respectively. Children and parents reported reduction in fatigue and improved gait outcomes after tSCS + SBLTT. Improvements in spasticity and walking function were sustained for 8-weeks after tSCS + SBLTT.

Interpretation: These preliminary results suggest that tSCS + SBLTT may improve spasticity while simultaneously maintaining neuromuscular coordination and walking function in ambulatory children with CP. This work provides preliminary evidence on the effects of tSCS and the combination of tSCS + SBLTT in children with CP.

AM Spomer, BC Conner, MH Schwartz, ZF Lerner, KM Steele (2024) “Multi-session adaptation to audiovisual and sensorimotor biofeedback is heterogeneous among adolescents with cerebral palsy”

Katie Landwehr JournalArticle, MotorControl, News, Publications , , , , ,

Journal Article in PLoS ONE

There is growing interest in the use of biofeedback-augmented gait training in cerebral palsy (CP). Audiovisual, sensorimotor, and immersive biofeedback paradigms are commonly used to elicit short-term gait improvements; however, outcomes remain variable. Because biofeedback training requires that individuals have the capacity to both adapt their gait in response to feedback and retain improvements across sessions, changes in either capacity may affect outcomes. Yet, neither has been explored extensively in CP.

Experimental protocol used to evaluate multi-session adaptation to multimodal biofeedback. Participants completed a four-day protocol using combined audiovisual and sensorimotor biofeedback. Audiovisual biofeedback on soleus activity was provided unilaterally on the more-affected limb whereas sensorimotor biofeedback was administered bilaterally using a resistive ankle exoskeleton. Each session was separated into baseline (1 minute), biofeedback (2, 10-minute bouts), and washout (1 minute) phases. The nominal torque value of the ankle exoskeleton was set at 0.1 Nm/kg during the first bout of the first session and incrementally adjusted by 0.025 Nm/kg over the subsequent bouts, according to the schedule shown. Overground walking data were collected pre- and post-intervention. A licensed physical therapist also performed a full physical examination at the pre-intervention session. Motion capture data were collected during at the pre- and post-intervention sessions and electromyography (EMG) data were collected bilaterally from the vastus lateralis, semitendinosus, soleus, and tibialis anterior across all sessions.Aim: The aim of this study was to evaluate the extent to which individuals with CP adapt gait and retain improvements during multi-session practice with a multimodal biofeedback paradigm, designed to promote plantarflexor recruitment. Secondarily, we compared overground walking performance before and after biofeedback sessions to understand if any observed in-session improvements were transferred. 

Methods: In this study, we evaluated the extent to which adolescents with CP (7M/1F; 14 years (12.5,15.26)) could adapt gait and retain improvements across four, 20-minute sessions using combined audiovisual and sensorimotor biofeedback. Both systems were designed to target plantarflexor activity. Audiovisual biofeedback displayed real-time soleus activity and sensorimotor biofeedback was provided using a bilateral resistive ankle exoskeleton. We quantified the time-course of change in muscle activity within and across sessions and overground walking function before and after the four sessions.

Results: All individuals were able to significantly increase soleus activity from baseline using multimodal biofeedback (p < 0.031) but demonstrated heterogeneous adaptation strategies. In-session soleus adaptation had a moderate positive correlation with short-term retention of the adapted gait patterns (0.40 ≤ ρ ≤ 0.81), but generally weak correlations with baseline walking function (GMFCS Level) and motor control complexity (ρ ≤ 0.43). The latter indicates that adaptation capacity may be a critical and unique metric underlying response to biofeedback. Notably, in-session gains did not correspond to significant improvements in overground walking function (p > 0.11).

Interpretation: This work suggests that individuals with CP have the capacity to adapt their gait using biofeedback, but responses are highly variable. Characterizing the factors driving adaptation to biofeedback may be a promising avenue to understand the heterogeneity of existing biofeedback training outcomes and inform future system optimization for integration into clinical care.