From birth to the end of growth, a femoral detorsion associated with a lateral tibial torsion can be observed. The absence or the exaggeration of this phenomenon leads to rotational abnormalities of the lower limbs called by parents as " in-toeing or out-toeing ". This represents one of the most frequent motives for consultation in pediatric orthopedics. The analysis of the respective position of knees and feet during walking and the measurements of femoral and tibial torsion allow the diagnosis of rotational abnormalities. During growth, the degree of these anomalies may increase or decrease spontaneously. As there is no evidence of a relationship between rotational abnormalities and arthritis, there are no preventive orthopaedic or surgical treatments. However, at the end of the growth, the persistence of functional symptoms leads to femoral or tibial derotation osteotomies.