Among the hypothesis about pathogenesis of medial knee osteoarthritis, the participation of modifications of the alignment of the limb in the frontal plane is known. The participation of the femoral and tibial torsions had been assessed by a few authors. In this study, the torsions have been measured by computerized tomodensitometry. The global torsional morphology of the limb has been defined by the measure of the Index of Cumulated Torsions. The values of torsions have been compared with the angle deformities measured in the frontal plane. The effects of the bone torsions on the position of the lower limb during the weight-bearing phase of the gait and the consequences about the knee have been studied.