[Radiologic study on postnatal ossification of the first metatarsal bone]

Classical descriptions of the ossification of the first metatarsal bone show the existence of a single proximal secondary ossification nucleus, mimicking the typical ossification of a phalanx. However, there are studies that show the presence of a second distal ossification nucleus and discuss its nature: epiphysis or pseudoepiphysis. The objective of the study is to establish the prevalence of such distal nucleus, determine its role in the growth of the radius and its relation with different qualitative variables.

We conducted a retrospective study that included 971 dorsoplantar images from 225 patients. We analyzed the presence of such nucleus, the age of appearance and closure, the relation with different qualitative variables and their contribution to the longitudinal growth of the first metatarsal bone.

The distal ossification nucleus appears in 40% of all images and in 81.1% of cases ages 4-7 years. Mean age of appearance is 3.07 years, while physeal closure occurs at a mean of 7.67 years. We found a significantly higher frequency of physeal closure in children, patients with Egyptian type foot, flat foot, and index-plus and Egyptian type foot combinations. The definitive length of the first metatarsal bone is greater in patients with a distal ossification nucleus.

We may state the presence of the distal ossification nucleus of the first metatarsal bone that behaves as a fertile growth cartilage.