Anterior process fracture or calcaneus secundarius: a case report.

Avulsion of the anterior process of the calcaneus accounts for nearly 15% of calcaneal fractures according to some sources. Yet, this fracture rarely has been reported in the radiology literature. Lateral plain radiography of the foot may demonstrate an ossific structure, distinct from the distal end of the calcaneus, overlying the head of the talus. However, the fracture may be particularly subtle and go undetected on plain radiography. Furthermore, it may be mistaken for the calcaneus secundarius (CS), an accessory ossicle of the anterior facet of the calcaneus identified in up to 5% of the population during cadaveric studies. This article describes the physical and radiological findings in a patient with an anterior process fracture and how this fracture can be distinguished from the CS.