Coxa pedis dysplasia in congenital convex pes valgus.

A dissection was carried out on bilateral congenital convex pes valgus in a newborn who died of congenital visceral malformations. The main finding was a modification in the neck-body relations of the talus. Nearly all muscles showed morphologic alterations. No insertional or histologic anomalies were shown. The plantar calcaneonavicular ligament was stretched and attenuated. The alterations observed in our case affected all the anatomic structures forming and stabilizing the coxa pedis. Our case suggests that the dysplastic evolution of the talar body-neck angle halts, and the neck assumes an adducted, medially inclined and plantar-tilted angle with respect to the talar body. We propose the term "congenital dysplasia of the coxa pedis" to describe this condition, because it emphasizes the primary alteration in the morphogenesis of the talocalcaneonavicular joint.