Genu varum (bowed legs), when extreme or unilateral, may result from a variety of underlying conditions: rickets, dyschondroplasia, osteogenesis imperfecta, osteochondritis, Blount disease (tibia vara), or injury to the medial proximal epiphysis of the tibia. Extreme degrees of physiologic bowing of the legs may occur in the young child and resolve over time without treatment (Figure 183-11).

Genu valgum (knock-knees) is often associated with pronation and is more apt to be marked in the child who is overweight. The degrees of knock-knee can be gauged by measuring the distance between the medial malleoli when the child is standing with the knees approximated (Figure 183-12). Injury to the lateral proximal tibial epiphysis can cause unilateral genu valgum (Figure 183-13). As with extreme bowing, underlying generalized diseases of the bone can cause marked bilateral genu valgum.

Figure 183-11 A, Extreme physiological bowing of the legs at age 18 months. B, Spontaneous resolution over time (age 7 years). (Sharrard WJW. Paediatric Orthopaedics and Fractures. Oxford, NY: Blackwell Scientific; 1971. Reprinted by permission of Blackwell Publishing Ltd.)

Figure 183-12 Marked degree of physiological genu valgum. At age 11 years the distance between the medial malleoli measured 4 inches. (Sharrard WJW. Paediatric Orthopaedics and Fractures. 2nd ed. Oxford, NY: Blackwell Scientific; 1979. Reprinted by permission of Blackwell Publishing Ltd.)

Figure 183-13 Unilateral genu valgum caused by previous injury to the lateral aspect of the right proximal tibial epiphysis. (Sharrard WJW. Paediatric Orthopaedics and Fractures. 2nd ed. Oxford, NY: Blackwell Scientific; 1979. Reprinted by permission of Blackwell Publishing Ltd.)