Kinematic-muscular synergies describe coupled neuro-muscular control and biomechanics of locomotion in children with cerebral palsy.

In children with cerebral palsy (CP), gait impairments originate from altered neuromuscular control and result in abnormal biomechanical outcomes. Muscle synergy analysis has been used to investigate modular motor control, but it relies exclusively on electromyographic (EMG) data. Kinematic-muscular synergies integrate EMG signals and kinematic variables, associating the neural commands with the biomechanics of the movement. This study examined kinematic-muscular synergies during gait in children with CP to identify alterations in both synergy structure and temporal activation. Seventeen children with CP were stratified based on their age (children, adolescents, and young adults). Twenty-two typically developed (TD) children served as the reference. Mixed-matrix factorization was used to extract kinematic-muscular synergies from 8 lower limb muscles and four joint accelerations in the sagittal plane. Spatial synergy structures were more consistent in TD and children than in adolescents (p = 0.04) and young adults (p = 0.001), while consistency of temporal coefficients was higher in TD (p < 0.001). Comparisons of patients with TD children revealed generally moderate preservation of spatial synergy structure, but temporal recruitment patterns diverged with age. Kinematic-muscular synergy analysis provides a quantitative link between impaired muscle coordination and altered biomechanics in CP gait, offering a promising tool for enhanced gait assessment and personalized rehabilitation planning.