Comparison of Center of Pressure and Center of Mass of Gait Initiation between Children with Typical Development and Children with Diplegia

[Purpose] The present study investigated the center of pressure (COP) and center of mass needed for gait initiation in children with typical development (TD), children with diplegia who independently walk (CP-GI), and children with diplegia who walk with a walker (CP-depGI). [Subjects] Three groups of 10 children (TD, CP-GI, & CP-DepGI), aged 7-10 years, were matched by age, weight, and height. [Methods] Each group was asked to independently initiate gait 3 times at a self-selected pace. The data were collected by a 3D motion analysis system (Vicon 612) and a force plate (AMTI-Advanced Mechanical Technology). The best trial of each participant was analyzed. The displacements and velocities of the COP and the COM were compared among the three groups. These parameters were analyzed using one-way ANOVA or the Kruskal-Wallis test. [Results] The COP-AP, COP-ML, COM-ML displacements and the COP-ML velocity before lift-off of the swing limb (phase 2) were similar among the three groups whereas they were somewhat different prior to movement (phase 1). Additionally, the COM-AP velocities in phase 2 were significantly different among the three groups. [Conclusion] This study provides basic data regarding the COP and the COM parameters that influence the achievement and efficiency of gait initiation in children. The data indicate the essential parameters for gait initiation and efficiency that should help physical therapists to appropriately treat children with spastic diplegia who cannot initiate gait or perform the task with a difficulty.