New developments in developmental dysplasia of the hip

Abstract

Developmental dysplasia of the hip (DDH) represents a spectrum of conditions that are present from the perinatal period. The term DDH is now preferred over congenital dislocation of the hip (CDH) because many cases have been reported in which the child’s hip examination appeared normal at birth but the hip was later found to be subluxated or dislocated.’ A normal infant’s hip is extremely difficult to dislocate. At birth the femoral head is deeply seated in the acetabulum. In hips with dysplasia, however, this tight fit between the femoral head and the acetabulum is lost, and the head can be displaced from the acetabulum. The term dysplasia in the newborn refers to any hip with a positive Ortolani sign (i.e., any hip that may be provoked to subluxate or dislocate or is subluxated-partial contact between the femoral head and the acetabulum-or dislocated-no contact between the femoral head and the acetabulum) and reducible. The term dislocation applies to complete unreducible dislocations that are extremely rare in newborns and are usually associated with other generalized conditions or anomalies, such as arthrogryposis or myelodysplasia. These rare antenatal teratologic dislocations account for only 2% of the cases in most series of newborns examined. Current management of DDH is based on knowledge of the pathology of DDH and acetabular growth and development, the natural history of untreated DDH, and the ongoing reevaluation of past treatment regimens. The goal of treatment of DDH should be a hip that will function normally for the patient’s lifetime. This implies that the hip has been anatomically reduced and that complications have been avoided, particularly aseptic necrosis. If the diagnosis of DDH is made within the first few weeks of life, there is a 95% success rate in management with devices such as the Pavlik harness because the pathologic changes in this age group are generally reversible. If DDH goes undetected, normal hip joint development is impaired. With increasing age at detection, particularly beyond 6 months of age, the obstacles to concentric reduction, both intraarticular and extraarticular, become increasingly difficult to overcome. Restoration of normal acetabular development is more uncertain and failure to maintain a concentric reduction is related to late subluxation and degenerative joint disease.