 The study will be in 3 parts: first one will be to address the key question of the lower limb frontal alignment based on both three-dimensional measurements of low-dose bi-planar X-rays and foot morphology assessment. Indeed, a major issue in the management of lower limb disorders is the ability to correctly assess abnormal development and decide on the most adapted treatment option. In particular, the link between lower limb disorders and foot morphology remain unclear. Recently, quantitative 3D measurement of the lower limb in children has been successfully assessed using low-dose biplanar X-rays. 