Developmental dysplasia of the hip

The hip is a “ball-and-socket” joint, which is not formed properly in DDH resulting in either a dislocated, dislocatable or subluxatable hip often with acetabular dysplasia.

It is seen in 1% babies but more common in first-born and in girls.

Risk factors

– Sibling having DDH/ first-degree family member with hip problems in early life

– Breech presentation, Oligohydramnios, Twins or multiple pregnancies

– Neuromuscular disorders, such as meningomyelocele or cerebral palsy

Clinical assessment

– Inspect asymmetrical skin folds in thighs or unilateral flat buttock

– Leg length discrepancy can be noted with hips & knees flexed at 90° (Galeazzisign)

– Otolani(able to relocate) and Barlow(able to dislocate) tests only detect subluxating hips (not dysplastic or dislocated hips) in a young child under 3m- note any ‘clunk’ not just clicky hips

– Reduced abduction of semi-flexed hip

– Palpation of posteriorly dislocated hip

– Externally rotated leg while walking

– Walking on a tip-toe, or painless limp with waddling gait (Trendelenburg positive)  

Investigations

– Ultrasound detects hip stability and acetabular development in infants.

– Xray of pelvic is used in young children once the femoral head ossification centre has developed.

– MRI scanning can also be used to identify hip dysplasia

Management

Early diagnosis leads to a better outcome.

– Newborn babies (or younger than 6m) are managed with ‘bracing’ with abduction splinting to keep hips within the sockets.

– This is done with dynamic flexion-abduction orthosis (Pavlik^® harness) for few months.

– Babies older than 6 months are treated with closed reduction and spica casting in milder cases.

– Surgery is needed for those who don’t respond to harness or are diagnosed late (after 6m). Options include open reduction with/ without soft tissue procedure followed by plaster cast.

– Older children may also require osteotomy to position hip within socket.

– A highly dysplastic acetabulum may need to be left untreated if not amenable to surgical procedure.

Complications

– DDH leads to degenerative arthritis and resulting disability, often requiring hip replacement surgery at younger age

– Surgery or Harness can lead to avascular necrosis of the femoral head