Developmental dysplasia of the hip (DDH) refers to an abnormal anatomic relationship between the head of the femur and the acetabulum. Without the usual ball-in-socket configuration, the joint will not develop normally, resulting in lifelong morbidity. The hip may be dislocated at birth or merely dislocatable, with dislocation occurring in the first months of life. DDH may present at any time during childhood, but is most commonly diagnosed at birth or in infancy. Early recognition leads to more rapid and less invasive treatment. Young infants usually can be treated without surgery, whereas most children diagnosed after the age of 2 require open surgical reduction.

Risk factors for DDH include female sex, breech presentation, and a positive family history. Girls who are breech are at particularly high risk. The presence of torticollis, metatarsus adductus, or an underlying neuromuscular disorder also increases the risk for DDH. Parents of older children may report a limp, a waddling gait, or a leg length discrepancy.

DDH is primarily diagnosed by the physical exam. The Ortolani and Barlow maneuvers detect most but not all DDH in the newborn period and during the first 4 months of life. The examiner must take care to examine the infant while she or he is calm, and to examine one hip at a time. A palpable clunk with either maneuver indicates a positive test. Ligamentous clicks generally do not indicate pathology. Asymmetry of femur length or skin folds also suggests the diagnosis. Limited abduction of the hip is a cardinal sign of DDH after 3 months of age. It is imperative that the clinician carefully perform and document the hip examination at each well visit because hip dysplasia may develop after a normal newborn exam. Ultrasound is the imaging study of choice in children younger than 4 months because it can determine mobility of the hip and the anatomy. After that age, plain radiographs are useful because the femoral heads are beginning to ossify.