[Natural history of congenital hip dislocation during the first year of life].

It seems obvious that congenital hip dislocation is determined by perinatal factors that are all the more "pathogenic" that the baby presents laxity (female sex or family laxity of the joints) and the hip is less mature (hereditary factor?). In our population, at the time of birth less than one child out of 1000 presents a dislocated hip that can be reduced (typical standard Ortolani sign). One or two percent present unstable hips that stabilize spontaneously in most cases. This stabilization can be expedited by correct diapering in abduction or may be hindered by such practices as wrapping infants from birth with their legs stretched and adducted, strapping the baby to a cradle-board, or perhaps even by putting the child to bed on its side. Stabilization may even be hindered by spontaneous asymmetrical postures that maintain the hip of the concave side of the baby in adduction, as in the pelvic obliquity syndrome of the newborn. The remaining children have a so-called stable hip which presents a variable degree of laxity on clinical examination and a variable degree of maturity on ultrasonography. The observation of established congenital dislocations in children who have been followed since birth (and such cases escape the most meticulous screening) suggests that in some hips there is no clear-cut dividing line between instability and laxity. Hips either stabilize or evolve into a fixed dislocation within the first three months, whereas it is only during the fourth month that X-ray examination may confirm the normality of such at-risk hips. Nevertheless, at that age, normality criteria are not very accurate.(ABSTRACT TRUNCATED AT 250 WORDS)