Ultrasound screening for developmental dysplasia of the hip.

BACKGROUND: Clinical examination of newborns has been shown to be inadequate for the early detection of developmental dysplasia of the hip (DDH). It is debatable whether US examination is a valid alternative. OBJECTIVE: To contribute further knowledge to the natural history of DDH; to examine the distribution of hip morphology as classified by Graf according to sex and risk factors in an unselected Italian population; to propose a temporal pattern of US screening of all newborns to detect DDH. MATERIALS AND METHODS: All newborns (n=8,896) sequentially delivered in the Maternal and Child Health Hospital of Milan underwent US examination in the first week of life and, when findings were within normal limits, in the third month of life. Subjects categorised at birth as Graf type 2a with alpha angle between 50 degrees and 52 degrees, underwent a further US examination at the end of the first month of life. Subjects with ambiguous findings at the 3-month examination were re-examined at the end of the fourth month of life. All infants with abnormal hips abandoned the screening process and underwent treatment. RESULTS. Overall, 56 cases of DDH were identified: 34 in the first week of life examination, 10 at 1 month; 10 at 3 months and 2 at 4 months. CONCLUSIONS. A two-step US screening of newborns is recommended: at the end of the first month and within the fourth month of life.