Age-related changes in three-dimensional foot motion during barefoot walking in children aged between 7 and 11 years old

Background: The biomechanical complexity of children's feet changes throughout childhood, yet kinematic development of the feet is poorly understood. Further work exploring the kinematic profile of children's feet would be beneficial to help inform our understanding of the typical development of children's feet. Research Question: Do three-dimensional segmental kinematics of the feet during gait relate to age in a sample of children age 7-11 years? Methods: This study was a secondary analysis of an existing database representing one hundred and twenty-one children age 7 - 11 years (90 male, 31 female; mean & PLUSMN; SD: age 9.57 & PLUSMN; , 1.17 years, height 1.37 & PLUSMN; 0.08 m, body mass 35.61 & PLUSMN; 9.33 kg). Fifteen, 9 mm retroreflective markers were attached to the right shank and foot of each participant in, line with the 3DFoot model. Multi-segmental joint kinematics were collected during barefoot walking. Sagittal, frontal, and transverse planar motion was described for the shank-calcaneus, calcaneus-midfoot, and midfoot-metatarsals segment of the right foot. Principal component analysis (PCA) was used to reduce the major modes of variation in the data to fully explore foot segment motion over the entire gait cycle. Correlations and multiple regression between PCA outputs with age, and potential confounding factors are presented. Results: Significant positive correlations were found between age and greater calcaneus, dorsiflexion, midfoot inversion and adduction, and metatarsal dorsiflexion, plantarflexion and abduction. There were no significant confounding effects of height, body mass, walking speed or gender on the relationships between age and PCA outputs. Significance: The findings from this study demonstrated a relationship between foot kinematics and age suggesting that the development of foot kinematics is ongoing until at least the age of 11 years. This work offers a comprehensive data set of inter-segmental kinematics which helps to advance understanding of the development of the pediatric foot.