Adolescent idiopathic scoliosis (AIS) involves complex tridimensional deformities of the spine. In case of progressive curve deformity, the use of spinal bracing remains the standard non operative treatment of moderate AIS. Most of the time, the different types of braces don't take into account the individual biomechanical properties of each patient's spine. Actually, it is essential to better understand the effect of the loads applied on the trunk and on the spine, and a 3D geometrical modelisation of these components is essential. Many studies have been publishing concerning the use of radiographs for the geometrical reconstruction of the spine, and more recently the EOS system. But even then, it is still necessary to obtain an important number of geometrical data and discretisation is still a long procedure.