Intermediate form of osteopetrosis with recessive inheritance.

The clinical and radiographic features of the intermediate form of osteopetrosis in two sibs are presented in which the disorder appears to have been inherited as a recessive trait. Although this form of osteopetrosis has been poorly delineated, its recognition is practically important in order to give an accurate prognosis. This paper also presents an unusual complication of bilateral avascular necrosis of the femoral head in the younger sib. Radiographic changes of the femoral heads suggest those of Legg-Calvé-Perthes disease, though the possibility of avascular necrosis following unrecognized femoral neck fracture is not completely excluded.