Stepping to Understand Lower Limb Impairments in Bilateral Cerebral Palsy

The purpose of this study is to investigate lower limb impairments in children with bilateral cerebral palsy during stepping tasks.

Individuals with bilateral cerebral palsy (BCP) sustain a neonatal brain injury that leads to altered neuromuscular control to the lower limbs. One commonly observed motor impairment from this altered control is loss of selective voluntary motor control (SVMC), defined as the ability to independently move the joints intentionally. Loss of SVMC typically manifests as knee and ankle joint impairment and abnormal coupling between the hip adductors and lower limb extensors. This can make stepping up or down a curb or stair challenging, but quantitative investigation in these closed-chain activities has been limited. This is especially important as performance in stair-climbing is associated with limitations to overall mobility and community participation in cerebral palsy. The overall aim of this proposal is to investigate the altered neuromuscular control that challenges stair walking in individuals with BCP. Participants who consent to the study will be instructed to perform multiple step-ups and step-downs on a single raised platform. The parameters of the stepping task may change by adding weight to the body or subtracting weight from the body. Using standard gait analysis techniques, biomechanical metrics such as joint kinematics and kinetics will be analyzed.

Participants will experience different body weight loading conditions - with body weight added by a weighted vest or removed using the ZeroG overhead harness.

Sum of the joint kinetics from the hip, knee and ankle, termed the "support moment" and measured in Nm.

At baseline and each loading level; During entirety of the stepping trial, from initial lift-off to final contact onto the single platform.

hip torque (measured in Nm) will be identified for the hip, knee, and ankle during the duration of the task.

At baseline and each loading level; During entirety of the stepping trial, from initial lift-off to final contact onto the single platform.

Knee angle (between the thigh and shank measured in degrees) will be identified during the duration of the task.

At baseline and each loading level; During entirety of the stepping trial, from initial lift-off to final contact onto the single platform.

Ankle angle (between the shank and foot measured in degrees) will be identified during the duration of the task.

At baseline and each loading level; During entirety of the stepping trial, from initial lift-off to final contact onto the single platform.

At baseline and each loading level; During entirety of the stepping trial, from initial lift-off to final contact onto the single platform.

At baseline and each loading level; During entirety of the stepping trial, from initial lift-off to final contact onto the single platform.

EMG data will be identified for underlying muscles of the ankle during the stance phases of the task.

At baseline and each loading level; During entirety of the stepping trial, from initial lift-off to final contact onto the single platform.

Inclusion Criteria: aged 5 years to 19 years typically developing with no diagnosed medical conditions that affect movement, OR with a diagnosis of bilateral cerebral palsy (including diplegia, tetraplegia, and quadriplegia) where the lower limbs are more affected than the upper limbs ability to independently step up, with or without assistive devices. Exclusion Criteria: lower limb surgery in the past year botulinum toxin injections to the lower limb muscles in the past 6 months cognitive dysfunction that would make following directions difficult comorbidities that would make participation unsafe.

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