[Congenital convexity of the feet. Anatomical study and practical conclusions]

The authors have studied the pathological anatomy of two congenital pes convex, (C.P.C) coming from an 8 days boy suffering of arthrogryposis. One of the feet has been dissected by stage whilst the other one has been operated on according to a procedure of correction of the deformities. The two feet combined an irreducible dislocation of the os naviculare on the neck of the talus, a calcaneo cuboïdeum subluxation, a moderate equinus of the hind foot, an important contracture of the extensor tendons and an elongation of the structural soft tissues of the sole. The main abnormalities of the talus and of the calcaneus involved the upper direction of the anterior articular facet, in relation to the dorsal dislocation of the os naviculare and the dorsal subluxation of the cuboïdeum. The subtalaris joint was little altered. The study of dissections and the clinical reports published connected with the observations of the authors confirm the pre-eminence of the transversal dislocation of the tarsus and of its irreducibility. On the other hand the abnormalities of the subtalar joint have been, probably over estimated. The sometimes important increase of talo calcaneal angle on A.P. radiographies may be explained by the incidence itself. The verticality of the talus is not a reliable feature of C.P.C. and the deformities of the fore foot are variable (pronation, supination). This study leads to a new definition of the C.P.C.: Congenital deformity of the foot with tarsi-transversa dislocation or subluxation involving mainly the talo-navicular joint. The criterious of diagnosis are debated and a logical surgical procedure of correction is suggested.