Morphological or functional criteria in evaluation of the newborn hip?

Classifying the infant hip as normal or dysplastic before the stage of radiological significance, in other words during the first three months of life, has always been trusted to functional maneuvers causing clinical signs. From the results it is possible to deduce if the hip morphology is normal or somehow altered. In other words, because insufficient radiographic significance makes it impossible to directly assess the "morphological" criterion, diagnosis of the state of the hip is carried out using an indirect "functional" criterion. In contrast to radiographic imaging, ultrasound screening is already significant in the first weeks of life; it is therefore now possible to obtain real images of the infant hip earlier than it was possible using radiography. This eliminates the need for symptomatic evidence of dislocation. As a result, the "functional" indirect criterion used up till now for early diagnosis of infant hip can today be replaced by a direct "morphological" criterion. This innovation is not without epidemiological consequences, and this must be taken into account in order to rationalise between the opposing risks of over or under estimating the incidence of congenital hip dysplasia.