3 Dimensional Study of Lower Limbs and Feet of Children in Standing Position

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. 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

Second part is to assess the reproducibility of the 3dimensional reconstructions whether they are made by a radiology technician, or by a so-called expert through collecting datas from 3 centers of pediatric surgery where EOS Imaging system is daily used to get spine or lower limb X-Rays. The investigators will include 20 children, divided as follow: six typically developing ones (control X-Rays or lower limb standing X-ray required for a medical reason not interfering with torsional or longitudinal axis of the limb), 6 non-typically developing (by example children who underwent a lower limb fracture), 6 cerebral palsy ones, and 2 children with extreme lower limb deformities. Reconstructions will be done twice in each center: once by a qualified operator, senior orthopedic surgeon, who followed a practical course, and once by a radiology technician, also used to the software.

First step will be to calculate the reproducibility for all parameters, depending on each subgroup of patient. Then, for each parameter, outliers' values will be analyzed and explained. They will be then suppressed from the datas to re-calculate the reproducibility. Finally, reproducibility of the obtained parameters will be compared to the one published in literature

Last part will be to work on the recently developed weight-bearing foot 3D reconstruction method for clinical use using the Parametric Personalized Modelling approach (PPM). This will allow having a better understanding and evaluation of foot's anatomy and patho-anatomy.