Developmental dysplasia of the hip (DDH) is a condition where the 'ball and socket' joint of the hips doesn't properly form in babies and young children.
It's sometimes known as congenital hip dislocation or hip dysplasia.
The hip joint attaches the thigh bone (femur) to the pelvis. The top of the femur (femoral head) is rounded like a ball and sits inside the cup-shaped hip socket.
In DDH, the socket of the hip is too shallow and the femoral head isn't held tightly in place, so the hip joint is loose. In severe cases, the femur can come out of the socket (dislocate).
DDH may affect one or both hips but is more common in the left hip. It's also more common in girls and firstborn children. About 1 or 2 in every 1,000 babies have DDH that needs treating.
Without treatment, DDH may lead to problems later in life, including:
- developing a limp
- hip pain – especially during the teenage years
- painful and stiff joints ( osteoarthritis )
With early diagnosis and treatment, most children are able to develop normally and have a full range of movement in their hip.
Within 72 hours of giving birth, your baby's hips will be checked as part of the newborn physical examination . Another hip examination is carried out when your baby is between six and eight weeks old.
The examination involves gentle manipulation of your baby's hip joints to check if there are any problems, and shouldn't cause them any discomfort.
An ultrasound scan is usually recommended within a few weeks if:
- the hip feels unstable
- there's a family history of childhood hip problems
- your baby was born in the breech position (feet first with their bottom downwards)
- you've had twins or a multiple birth
- your baby was born prematurely – before the 37th week of pregnancy
Sometimes a baby's hip stabilises on its own before the scan is due.
Babies diagnosed with DDH early in life are usually treated with a fabric splint known as a Pavlik harness. This secures both of your baby's hips in a stable position and allows them to develop normally.
The harness needs to be worn constantly for several weeks and shouldn't be removed by anyone except a health professional. The harness may be adjusted during follow-up appointments and your clinician will discuss your baby's progress with you.
Your hospital will provide detailed instructions on how to look after your baby while they're in a Pavlik harness. This will include information on:
- how to change your baby's clothes without removing the harness (nappies can be worn normally)
- cleaning the harness if it's soiled – it still shouldn't be removed, but may be cleaned with detergent and an old toothbrush or nail brush
- positioning your baby while they sleep – they should be placed on their back and not on their side
- how to help avoid skin irritation around the straps of the harness – you may be advised to wrap some soft, hygienic material around the bands
Eventually, you may be given advice on removing and replacing the harness for short periods of time until it can be permanently removed. You'll be encouraged to allow your baby to move freely when the harness is off and swimming is often recommended.
Surgery may be needed if your baby is diagnosed with DDH after they're six months old, or if the Pavlik harness hasn't worked. The most common surgical technique is known as reduction, which involves placing the ball of the femur back into the hip socket.
Reduction is carried out under general anaesthetic and may be performed as either:
- closed reduction – the ball is placed in the socket without making any large cuts (incisions)
- open reduction – an incision is made in the groin to allow the surgeon to place the ball in the socket
Your child will need a hip cast for at least six weeks after surgery. Their hip will need to be checked under general anaesthetic again after this time to make sure it's stable and healing well. After this investigation, a cast will probably be needed for at least another six weeks to allow the hip to fully stabilise.
Some children may also require bone surgery (osteotomy) during an open reduction, or at a later date to correct any bone deformities.
Late-stage signs of DDH
The newborn physical examination and the check at six to eight weeks aim to diagnose DDH early. However, sometimes hip problems can develop after these checks.
It's important to contact your GP as soon as possible if you notice your child develops any of the following symptoms:
- restricted movement in one leg when you change their nappy
- one leg drags behind the other when they crawl
- one leg appears longer than the other
- uneven skin folds in the buttocks or thighs
- a limp, walking on toes or developing an abnormal 'waddling' walk
It's important to remember that DDH can't be prevented and it's nobody's fault. A baby's hips are naturally more flexible for a short period after birth.
However, if your baby spends a lot of time tightly wrapped with their legs straight and pressed together (swaddled), there's a risk this may slow their hip development. Using 'hip healthy' swaddling techniques can reduce this risk. Make sure your baby is able to move their hips and knees freely to kick.
You can read about hip-healthy swaddling on The International Hip Dysplasia Institute website.