To date, there are only a few cases of symptomatic os calcaneus secundarius (CS) published in the literature, of which none are as large as the one we describe. However, all these cases outline the importance of CS as a potential differential diagnosis in athletic foot injuries or persistent ankle pain.

Os calcaneus secundarius (CS) is not to be confused with the more often reported entity of symptomatic calcaneus accessorius. Other entities to be considered are the os cuboideum secundarium and the os sustentaculum secundarium.

In a post-traumatic setting, CS can be mistaken for fracture anterior process of the calcaneus. Therefore distinct nomenclature has to be defined. Calcaneonavicular coalition is another radiological and clinical differential diagnosis.