Hip sonography: background; technique and common mistakes; results; debate and politics; challenges.

Developmental dysplasia of the hip (DDH) is the commonest 'congenital' disease of the locomotor system throughout the world. According to the World Health Organisation (WHO) Bone & Joint Decade (2000-2010) 10%-15% of patients who are under the age of 50 when they require a hip replacement do so because of infant hip dysplasia.The background; technique and common mistakes; results; debate and politics; and the challenges of infant hip sonography are reviewed.