Developmental dysplasia of the hip

Developmental dysplasia of the hip (DDH, or congenital dislocation of the hip) is a spectrum of disorders ranging from partial subluxation to frank dislocation of the hip. It is thought that high concentrations of the maternal hormone relaxin contributes to the laxity of the hip joint. DDH is found in 1 in 1000 births, and is six times more common in females. The left hip is more likely to be dislocated that the right. Risk factors for DDH include a positive family history, breech delivery, spinal/neuromuscular abnormalities (e.g. spina bifida and talipes equinovarus) and oligohydramnios.

Neonatal screening for DDH is by two methods: Barlow's test (the hip can easily be displaced posteriorly out of the acetabulum or adduction of the leg with posterior pressure) and Ortolani's manoeuvre (the femoral head can be reduced back into the acetabulum on abduction of the leg with anterior pressure). These tests are routinely done at birth and 6 weeks of age. These manoeuvres have a good positive predictive value (e.g. if the examination is positive, the patient has DDH) but has a very poor negative predictive value (e.g. many patients with a normal examination are later found to have DDH). DDH may be present with assymmetrical skinfolds, limited abduction, shortening of the affected limb and limp. If spotted early, DDH responds to conservative treatment. The hips can be placed in abduction (using Craig's splint) or the child can be put in a restraining device (Pavlik harness) for several months. Progress should be monitored by ultrasound or X-ray. If conservative measures fail, open reduction and femoral osteotomy may be required. Necrosis of the femoral head is a potential complication of DDH.