The current recommendations are for the term “developmental dysplasia of the hip” (DDH) as a replacement for the previous name of “congenital hip dislocation” (CHD). This new nomenclature includes all spectrum of abnormalities possible for hip disorders among newborns, because DDH is a generic term that describes a wide range of anatomical abnormalities of the hip, which may be congenital in nature, or may develop during children’s first months of life.

   DDH describes the wide spectrum of abnormalities that affect growing hips, from dysplasia to joint dislocation, and going through the different degrees of coxofemoral subluxation (1, 2).

   Dysplasia of the hip is a term that denotes an abnormality of size, morphology or anatomical orientation, in relation to the organization of either the femoral head or the acetabular cavity, or both. Acetabular dysplasia is characterized by an immature acetabulum, which may cause subluxation or luxation of the femoral head. In cases of subluxation of the hip, the femoral head is dislocated from its normal anatomical position, but there is still some contact with the acetabular cavity. In cases of luxation of the hip, there is no contact between the femoral head and the acetabular cavity. Hips are described as “unstable” when the joint is reduced, in the anatomical position, but when subluxation or luxation of the joint can be caused (3).

   The incidence ranges from as low as 1 per 1,000 to as high as 34 per 1,000. Higher incidences are reported when ultrasonography is also used in addition to clinical examination (4).

   Risk factors include first born status, female sex, positive family history, breech presentation and oligohydramnios (5).

  The etiology of DDH is multi factorial. There are a number of predisposing factors that lead to the development of DDH, including ligament laxity, breech presentation, postnatal positioning, primary acetabular dysplasia (6).

   The natural history of untreated hip dysplasia can be more variable with some patients presenting with minor symptoms and others only found to have hip dysplasia as an incidental finding on radiographic imaging. There is growing evidence, however, that hip dysplasia leads to progressive degenerative joint disease in adults, in particular females. Long-term follow up of treated subluxed and dysplastic hips also revealed a higher incidence of degenerative joint disease in hips that resubluxed over time (7, 8).

   A common method of screening is serial physical examinations using the Barlow and Ortolani maneuvers and selective ultrasound if indicated (9). (Fig.1)

   Therapy is most effective and tends to be noninvasive when DDH is detected early (10). Untreated, DDH can progress to abnormal gait, leg length discrepancies, early osteoarthritis, and, rarely, avascular necrosis (11). Patients younger than 6 months old are typically braced in Pavlik harnesses. Surgical hip reduction and casting are used for patients who fail the Pavlik harness or those with late diagnoses. Iliac and femoral osteotomies are reserved for severe cases of DDH (12).

   DDH is being diagnosed at an earlier age, leading to more successful and less invasive treatment. However, there continues to be "missed" or late cases, even in countries that have instituted screening programs for all infants. Some infants miss the initial screening examination; some infants who at first appear to have normal hips later develop acetabular dysplasia. Even when treatment is instituted at an early age and is appropriate, acetabular dysplasia may persist and require acetabular reconstruction (13).