Developmental dysplasia of the hip (DDH, formerly known as congenital dislocation of the hip) describes any abnormality found in the neonatal hip joint. The degree of abnormality varies considerably. The problem may arise from structural defects in the head of the femur, the acetabulum or surrounding structures. Approximately 1 in 1000 births are affected and it is more common in the left hip.
Many risk factors are indicated in DDH. Previously, all babies with any risk factor were screened in the UK. However, only babies who are breech presentation or those who have a positive family history are now screened as these have been identified as the most significant risk factors. Other risk factors include oligohydramnios (reduced amniotic fluid volume), firstborn babies, race (high in Native Americans) and gender (80% of cases are female).
Diagnosis is suggested during newborn checks that all babies receive before leaving the hospital. It can only be confirmed on ultrasound.
Examination of the hips in a newborn
- Inspection: Look for difference in leg length by flexing knees fully and comparing knee height (Galeazzi’s sign). Look for defined skin creases (not very sensitive).
- Ortolani’s test: With knees flexed and in the midline the hip is abducted until flat on the bed. The examiners fingers should be on the greater trochanter.
- Barlow’s test: With hips in the position post-Ortolani’s test hips are adducted back to the midline with pressure applied posteriorly along shaft of femur.
During a positive Ortolani’s test a ‘clunk’ will felt by the examiner as the femoral head is reduced from a posterior position into the acetabulum. During Barlow’s the femoral head is returning to its dislocated position.
The most common treatment for DDH is the use of a Pavlik harness. The Pavlik harness holds the child’s legs in an abducted position with the hip flexed (much like Ortolani’s). The child is able to further flex or abduct the hip but adduction and hip extension are limited. The harness must be worn continuously for at least 6 weeks.
In children over 6 months of age the harness is not indicated and surgical reduction may be required. If DDH is left untreated there is a high risk of early onset arthritis