The genu valgus is the variation of the shaft of the lower extremities in the frontal plane in which there is an increased space between the ankles to keep the knees together. Knees is known as X or as scissors, so that the knees are close together and no great separation between the ankles. During growth produced a series of normal variations (physiological changes) and also various forces acting on tips given by modifying the way that the supporting structures are still developing joint. Finally, around age 8 the final alignment of the lower limbs is achieved and genu valgus resolved spontaneously. After this period a surgical treatment is necessary.