 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. The population studied will be 133 patients, aged 6 to 16 years old, for whom a lower limb standing X-ray is required for a medical reason not interfering with torsional or longitudinal axis of the limb such as, for example, patients consulting for non-specific lower limb pain. All patients will have low-dose biplanar X-rays using the EOS system EOS Imaging, France. From the EOS bi-planar images, a 3D patient-specific parametric model of the lower limbs will be obtained. The clinical indices i.e. mechanical femoral MFA and mechanical tibial MTA angles, Hip Knee Shaft angle HKS and femoro tibial angle FTA will then be automatically computed. For each clinical parameter, the mean value and standard deviation will be calculated, depending on the age group, gender, and on foot morphology 