Developmental dysplasia of the hip: ultrasound evaluation.

Developmental dysplasia of the hip (DDH) is a commonly encountered pathology in everyday pediatric radiology practice. Early detection of the condition and early institution of therapy are crucial in optimizing patient outcomes and preventing long-term morbidity. Ultrasound is the imaging modality of choice in evaluating DDH in patients less than 4 months of age and is also used to evaluate infants undergoing treatment with an abduction device to monitor therapy response. This article will begin with a general review of DDH, including the underlying pathophysiology of the condition and which patients meet screening criteria for developmental hip dysplasia ultrasound assessment. The paper will then describe the ultrasound techniques utilized in screening for DDH and how to apply the Graf classification system to determine if a hip is normal or dysplastic, as well as how to grade the severity of dysplasia. Finally, the paper will address specialized ultrasound techniques used to follow patients undergoing treatment with an abduction device to monitor therapy response.