Congenital dysplasia of the hip: the lax (subluxatable) newborn hip.

During a 4-year period, 15,149 newborns were examined for hip abnormalities. Ninety-two infants (0.61%) were found to have subluxatable (lax, but not dislocatable) hips. The profile of this group was similar to patients with dislocated hips, with an increased frequency of females, breech presentations, left-sided involvement, and associated postural deformities. A significant number showed acetabular dysplasia or persistent hip laxity despite treatment with an abduction brace. We concluded that the newborn subluxatable hip arises from the same antecedents as frank dislocation, is not always benign, and is best managed if detected and treated at birth.