[Axes of the legs in childhood. What is pathologic?].

At birth the lower extremity is characterized by a varus axis in the lower leg and the knee joint in the frontal plane (bowleg) and an increased femoral antetorsion and a neutral or increased medial torsion of the lower leg in the transverse plane. By the time growth is complete a normal valgus axis of 5-9 degrees has developed in the lower limb and the femoral antetorsion has decreased to about 15 degrees. The lower leg will show a normal external rotation of 15 degrees on average. The evolution of the axis values in the lower extremity is influenced by changing compressive and propelling forces acting on the growth plates as the child adopts an upright posture. There is a wide range of normal values, but pathologic development of the leg axes is rare and mostly idiopathic. Secondary deviations of the axis from normal can occur. Careful clinical examinations are necessary to differentiate between pathologic and physiological variations. Further apparative diagnostic procedures help to elucidate the etiology and are essential for surgical planning. Nonoperative treatment alone is rarely sufficient to influence the deformity.