Site-Specific Transmission of a Floor-Based, High-Frequency, Low-Magnitude Vibration Stimulus in Children With Spastic Cerebral Palsy

ObjectiveTo determine the degree to which a high-frequency, low-magnitude vibration signal emitted by a floor-based platform transmits to the distal tibia and distal femur of children with spastic cerebral palsy (CP) during standing.DesignCross-sectional study.SettingUniversity research laboratory.ParticipantsChildren with spastic CP who could stand independently (n=18) and typically developing children (n=10) (age range, 4–12y) participated in the study (N=28).InterventionsNot applicable.Main Outcome MeasuresThe vibration signal at the high-frequency, low-magnitude vibration platform (approximately 33Hz and 0.3g), distal tibia, and distal femur was measured using accelerometers. The degree of plantar flexor spasticity was assessed using the Modified Ashworth Scale.ResultsThe high-frequency, low-magnitude vibration signal was greater (P<.001) at the distal tibia than at the platform in children with CP (.36±.06g vs .29±.05g) and controls (.40±.09g vs .24±.07g). Although the vibration signal was also higher at the distal femur (.35±.09g, P<.001) than at the platform in controls, it was lower in children with CP (.20±.07g, P<.001). The degree of spasticity was negatively related to the vibration signal transmitted to the distal tibia (Spearman ρ=−.547) and distal femur (Spearman ρ=−.566) in children with CP (both P<.05).ConclusionsA high-frequency, low-magnitude vibration signal from a floor-based platform was amplified at the distal tibia, attenuated at the distal femur, and inversely related to the degree of muscle spasticity in children with spastic CP. Whether this transmission pattern affects the adaptation of the bones of children with CP to high-frequency, low-magnitude vibration requires further investigation.