Developmental dysplasia of the hip or DDH: causes

There’s no one cause of developmental dysplasia of the hip or DDH.

DDH is more likely to happen if your child was born breech (the position in the womb where the baby’s head is up instead of being down) or if you have a family history of DDH. DDH is also more common in girls than in boys by a ratio of 4 to 1. It’s also more common in first-born children.

Sometimes when babies are born, the structures that support the hip might be loose and the socket of the hip joint might be shallow. These problems might cause the hip to become unstable and even come out of the joint – this is a dislocated hip.

DDH can sometimes be caused by swaddling, or wrapping your baby’s legs too tightly. To learn more about the right way to wrap your baby, check out our video on wrapping a newborn or our illustrated guide to wrapping babies.

Signs and symptoms of DDH

Developmental dysplasia of the hip or DDH can vary from mild to severe, and one or both hips can be affected. It isn’t painful for babies and young children.

The signs of DDH in your newborn won’t always be obvious to you, but a skilled and experienced doctor, midwife or child and family health nurse can spot the signs. These professionals will do a series of careful checks and tests on your baby. These checks and tests are described below.

If DDH isn’t picked up when your child is a newborn, you might notice later on that the skin creases in the backs of your baby’s thighs are uneven. Or when you’re changing your child’s nappy, you might notice that one thigh doesn’t seem to move as far out or as easily as the other. One thigh might look shorter than the other thigh.

Later still, your child’s leg on the affected side might seem to be in an abnormal position, or the leg might even be shorter than the other. Your child might walk with a limp or with her pelvis tilted to one side.

Dislocated hip occurs in about 1 in 1000 births. Mild abnormalities that need treatment occur in up to 1 in 100 births. Usually, only one hip is affected, most commonly the left hip, but both hips are affected in 25% of cases.

When to see a doctor about signs of DDH

You should take your child to your GP if you notice any of the signs and symptoms described above. If there’s any doubt, your GP will send your baby to have an ultrasound. Your GP might send you and your baby to a paediatric orthopaedic surgeon for a specialist opinion.

Tests for DDH

Doctors and/or midwives do a very careful physical examination of both hips in all newborn babies in the first few days of life. Your GP or child and family health nurse will do these examinations again at six weeks. And your child and family health nurse will check your baby’s hips at every appointment in the first 12 months of your baby’s life.

The doctor, midwife or child and family health nurse will check very carefully for any signs of DDH or an unstable hip. The doctor or nurse might feel a faint ‘clunk’ in your baby’s hip or hips. This might be caused by stretched ligaments and just need monitoring.

But if there’s abnormal movement of the hip as well as the clunk, it’s likely that your child has DDH.

When experienced health professionals do these tests, the tests pick up most cases of DDH, although the tests aren’t reliable after eight weeks of age. If your baby is in a high-risk group or has an abnormal result from the physical examination, your baby will probably be sent for an ultrasound.

Treatment for DDH

If your baby is diagnosed with DDH when he’s a newborn or young baby, treatment is usually simple and straightforward, and it usually fixes the problem completely.

The later DDH is diagnosed and treatment started, the more difficult it is to fix. It’s also harder to know how well treatment will work.

If the doctor suspects your newborn baby has a dislocated hip, your baby might be placed immediately in a special harness or splint, which holds the hip in the socket of the hip joint by keeping the thighs apart. Your baby will wear this for around three months.

If treatment starts after your child turns one, your baby might need traction and often surgery, followed by 6-9 months in a plaster cast. The cast is changed every few weeks to allow for growth.

DDH prevention

Health professionals will check for DDH throughout the first year of your baby’s life.

If you have a family history of DDH or your baby was breech, health professionals will take special care when they examine your baby.

Although you can’t prevent DDH, early detection and immediate treatment can make a big difference.