[Lesions of the hip in congenital myxedema in children].

A series of 51 cases of congenital myxoedemia in children was analyzed to determine incidence of associated hip lesions. Mechanisms of epiphysial and articular cartilage growth are reviewed and events summarized that occur normally in the "growing hip": the upper femoral nucleus, and orientations of femoral neck and their physiologic variations. The role of thyroid hormones in bone growth is also discussed. Reviewed in greater detail are the myxedematous hips in children, or epiphysial dysgenesis, the causes of delay in bone maturation, the effect of substitutive therapy and mineralization disorders. In contrast to the richness of radiographic data, often very disturbing, restriction or even absence of functional signs is almost a constant feature, enabling a diagnosis of Legg-Perthes-Calvet's disease to be rejected, certain radiologic images being considered wrongly as comparable. Radiography provides images varying from delayed ossification of a sometimes very long upper femoral nucleus, termed "joint emptiness", to "pseudo-fragmentations" that are frequently encountered and are actually progressive ossifications. These sometimes progress towards deformity of femoral head in coxa plana but are usually well adapted to the acetabulum, reducing initial fears. Different parameters studied in the 51 patients are analyzed and an optimistic conclusion given, since neonatal screening for congenital myxedema and subsequent therapy should eliminate skeletal complications, particularly in the hip.