Anomalous multifocal ossification of the os calcis.

While accessory ossicles are relatively common in the feet, major developmental chondro-osseous variations in otherwise normal feet appear to be extremely unusual. The "bifid os calcis" has been reported infrequently since its first description by Sever in 1930. The majority of cases are fortuitously diagnosed, usually in children three years of age or older. The current case was diagnosed shortly after birth. The most obvious roentgenographic finding was punctate ossification in the anterior portion. As in other cases, this appeared to be a solitary, bilateral variation of chondro-osseous maturation. Foot development in the fetus includes considerable variation in the development of the calcaneal ossification center and at least two examples of multiple ossification centers.