METHOD : 1. Geometrical reconstructions Volumic MR acquisitions were performed on an unilateral newborn clubfoot (11 months) using a optimised protocol defined with the ragiologist (Baunin et al.1994). Typical parameters of acquisitions were a field of view of 180x180 with a matrix pixel size of 512x512 and 1mm joined slice thickness. Usually sixty to eighty slices were obtained. Geometrical reconstructions of different structures were obtained via an image processing SIP305 (© Inserm, Hobatho 1993), the visualization of the was done via an pre and post processing Patran (© MSC, Corp). Reconstructions of the different structure of the bones (black : osseous nucleus, white:cartilagineous anlage). stack of MR Slices of the feet 2. Calculations of the axes of rotation Assumptions : The bimalleolar axis (defined by the center of the fibula and the distal part of the tibia) is not modified by the clubfoot deformity. The different steps were to superimpose the abnormal to the normal foot relative to the bimalleolar axis, and to define the points of the different bones at the initial point (normal foot) and the final point (abnormal foot). The points were obtained from the eigenvectors of the calculated geometrical principal axes of inertias (with a unit mass) (Johnston et al. 1995). Then a program based on the calculation of the helical axes theory has been used to define the axes of rotation. Reproducibility : The reproducibility of the method has been tested by performing three different reconstructions and calculations by the same operator. Calculations were performed on both structures (bone and cartilage).