Males are affected twice as much as females. The precise etiology remains unknown. Thought to be secondary to an insult that occurs to the limb bud during the second to eighth week of fetal development. Genetic factors do not appear to be involved. Must be thought of as part of a spectrum of congenital deformities involving the entire lower extremity.
Clinical findings are dependent upon the degree of fibular hypoplasia.
Knee usually in valgus with varying degrees of instability. Anteromedial bowing of the tibia with a skin dimple present over the anterior aspect of the tibia at the apex of the deformity. Ankle usually in severe equinovalgus with rigid hindfoot. Frequent absence of lateral rays of foot. Associated anomalies involving upper extremities and viscera can be seen but are fortunately rare.