LAUSR

The term ‘developmental dysplasia of the hip’ (DDH) includes a wide spectrum of hip alterations: neonatal instability; acetabular dysplasia; hip subluxation; and true dislocation of the hip. DDH alters hip biomechanics, overloading the articular cartilage and leading to early osteoarthritis. DDH is the main cause of total hip replacement in young people (about 21% to 29%). Development of the acetabular cavity is determined by the presence of a concentrically reduced femoral head. Hip subluxation or dislocation in a child will cause an inadequate development of the acetabulum during the remaining growth. Clinical screening (instability manoeuvres) should be done universally as a part of the physical examination of the newborn. After two or three months of life, limited hip abduction is the most important clinical sign. Selective ultrasound screening should be performed in any child with abnormal physical examination or in those with high-risk factors (breech presentation and positive family history). Universal ultrasound screening has not demonstrated its utility in diminishing the incidence of late dysplasia. Almost 90% of patients with mild hip instability at birth are resolved spontaneously within the first eight weeks and 96% of pathologic changes observed in echography are resolved spontaneously within the first six weeks of life. However, an Ortolani-positive hip requires immediate treatment. When the hip is dislocated or subluxated, a concentric and stable reduction without forceful abduction needs to be obtained by closed or open means. Pavlik harness is usually the first line of treatment under the age of six months. Hip arthrogram is useful for guiding the decision of performing a closed or open reduction when needed. Acetabular dysplasia improves in the majority due to the stimulus provoked by hip reduction. The best parameter to predict persistent acetabular dysplasia at maturity is the evolution of the acetabular index. Pelvic or femoral osteotomies should be performed when residual acetabular dysplasia is present or in older children when a spontaneous correction after hip reduction is not expected. Avascular necrosis is the most serious complication and is related to: an excessive abduction of the hip; a force closed reduction when obstacles for reduction are present; a maintained dislocated hip within the harness or spica cast; and a surgical open reduction. Cite this article: EFORT Open Rev 2019;4:548-556. DOI: 10.1302/2058-5241.4.180019