The ultrasonographic image of the infant hip affected by developmental dysplasia with a positive Ortolani's sign.

Instability of the hip may be assessed by the Ortolani and Barlow tests, which are the keystone of clinical screening for developmental dysplasia of the hip (DDH). However, Ortolani's sign implies that there is strong evidence of a severe form of DDH with a completely dislocated, but still reducible, femoral head. Barlow's test addresses several different forms of "instability" of the hip that are quite difficult to describe and in 80% of cases disappear during growth. For this reason, Ortolani's sign in a baby should be considered an indication for emergency treatment to reduce and stabilise the hip while it is still reducible. The increasingly widespread use of US of the hip in newborns and infants has enabled clinicians to observe the hip from the first day of life and to establish both the static and dynamic relationships of the femoral head and acetabulum. The purpose of this paper is to describe the US pattern and relative classification of the hip affected by Ortolani's sign and examined by Graf's method, and to confirm through US that Ortolani's sign should be considered a totally reliable specific test for the identification of dislocation of the infant hip.