Biomechanical maturation of joint dynamics during early childhood: updated conclusions.

Dynamic parameters have been commonly explored to characterize the biomechanical maturation of children's gaits, i.e., age-revealing joint moment and power patterns similar to adult patterns. However, the literature revealed a large disparity of conclusions about maturation depending on the study, which was most likely due to an inappropriate scaling strategy and uncontrolled walking speed. With the first years of independent walking, a large growth in height and a large variability of dimensionless walking speed are observed. Moreover, the dynamic parameters were not well studied during early childhood. In the present study, seventy-five healthy children between 1 and 6 years of age were assessed during gait trials at a self-selected speed. Four hundred and sixty-two gait trials constituting five age groups with comparable dimensionless walking speeds were selected. 3D joint moments and the power of the lower limbs were computed and expressed using a dimensionless scaling strategy (according to body weight, leg length and the acceleration of gravity). Statistical analysis was performed to examine inter-group differences. Based on the current results, we concluded the biomechanical maturation of joint dynamics occurred around an age of 4 years for the ankle and between 6 and 7 years for the knee and the hip. Moreover, age group comparisons seemed more appropriate in young children using both the dimensionless strategy and a similar walking speed. Future investigations will be conducted on an older population (i.e., adding children older than 6 years) to clearly define the status of knee and hip biomechanical maturation.