[Longitudinal epiphyseal bracket of the first metatarsus (delta bone)]

The longitudinal epiphyseal bracket (LEB) or delta bone is a rare congenital ossification anomaly generally observed in finger or toe phalanges but occasionally in the metatarsus or metacarpus. LEB is initially composed of cartilage forming a bracket linking the proximal and distal epiphyses and causing defective growth of the primary ossification focus. Changes in bone growth secondary to the presence of a LEB would be the cause the angle malformations and length discrepancies observed in these subjects. This raises significant therapeutic problems and repeated surgical interventions when the diagnosis is not established early enough. The clinical presentation of LEB of the first metatarsus is similar to metatarsus adductus or hallux varus primus. The particular aspect on the plain x-ray enables the diagnosis.

We operated five feet presenting LEB of the first metatarsus in three children aged on average 23 months (range 8 months to 3 years 10 months). The cartilage bracket was removed, followed by metatarso-phalangeal centromedullary pinning. We studied the course of the angle and length deformities and report outcome at mean follow-up of 4 years 11 months (range 2 years to 3 years 10 months).

Clinical improvement with correction of the angle deformities was observed in all feet. The length discrepancies did not resolve completely. The degree of correction depended on the age at the time of surgery.

In light of the results obtained in this series and considering the negative prognosis of late surgical management, it would be advisable to obtain a plain x-ray of the foot in all children presenting metatarsus adductus associated with a short first ray.