[Epiphyseal dysplasia of the femoral head in monozygotic twins].

We present monozygotic twin girls with bilateral epiphyseal dysplasia of the femoral head (DECF). DECF is a rare condition reported mainly in boys before the age of five years. It consists of a state of non-ossification characterized by flattening and fragmentation of the femoral head. It is invariably followed by 100% healing. The differential diagnosis is primarily from Legg-Calvé-Perthes' disease (LCPD), which, however, occurs mainly after the fifth year followed by aggravation of the symptoms during the following 18 months. This condition leads to secondary degenerative changes in several hips. Although DECF and LCPD may be two entities of the same disease it is necessary to distinguish clinically between them, as the prognosis and the treatment are different.