Retinoic acid-induced clubfoot-like deformity: pathoanatomy in rat fetuses.

The purpose of this assay was to study the hindfoot patho-dynamic in clubfoot-like deformity during fetal development. Experimental induction of clubfoot-like deformity in rat fetuses was produced by maternal administration of retinoic acid (120 mg/kg body weight) as a single intragastric dose on day 10 of pregnancy. Hindlimbs from fetuses at 17, 19, and 21 days were removed, and serial sections in three planes were made. Experimental and control hindlimbs were studied. There was clubfoot-like deformity in 86.5% of the experimental fetuses and none in the controls. Other associated malformations found were craniofacial (96.3%), neural tube (75.7%), and club-hand (40.3%) defects. Persistence of the embryonic position of the talus and tibia in fetuses with severe clubfoot-like deformity was observed. No overlapping between talus and calcaneus was seen. An equinus position, medialization of anterior segment, and lateralization and inward torsion of the posterior body of the calcaneous were observed. Results of this study showed that there are rotational anomalies in the hindfoot and full hindlimb from the beginning of the fetal period, and these anomalies increase during development. This simple model may allow us to gain better knowledge in congenital clubfoot deformity.