Why are babies' hips checked at birth?

All babies have a physical examination soon after they are born; the examination of the hip joint is part of this examination. The GP or clinic doctor checks the hips again at around six - eight weeks. This is because some babies may have hips that are not growing properly; a condition called Developmental Dysplasia of the Hip (DDH). Some babies seem to be more at risk of developing DDH than others.

Normal Hip Development

How does a baby's hip grow?

For the hip joint to grow normally the ball shaped head of the thigh bone (femur) needs to be inside the cup shaped socket on the side of the pelvis (called the acetabulum). The head of the femur is held in place by ligaments, muscles and a joint capsule.

Abnormal Hip Development

If the head of the femur is not held tightly in place, the socket may be flatter than usual; this is called acetabular dysplasia. It makes the joint less stable and the head of the femur may be able to move in and out of the socket. This is called a dislocatable or subluxated hip. If the head of the femur loses contact with the socket and stays out of the joint, this is called a dislocated hip. These are both forms of DDH.

What causes DDH?

Some babies are born with dislocatable or unstable hips because around the time of delivery, hormones in the mother cause ligaments around her birth passage (pelvis) to relax a bit, to make it easier for the baby to pass through her pelvis during birth. These hormones may pass through the placenta to the baby and cause the ligaments around the baby's joints to relax, making the baby's hip joint less stable. As the level of hormones in the baby decreases, the ligaments around the hip tighten again.

Other causes of a hip joint not developing normally are not fully known, but some of the risk factors include:
- genetic factors (this means the problem is more common in families where another person in the family has also had a developmental problem with a hip)
- factors during the baby's development before birth, for example if the baby is in the breech position or has been in a squashed position in the womb
- significant foot deformities (which need treatment)
- significant newborn torticollis ( twisted or wry neck)
It is also more common in first-born baby girls.

How are the hips checked?

The physical tests are known as the Ortolani and Barlow Tests. The baby is laid on his or her back and the hips are moved gently outwards. A distinctive 'clunk' suggests a possible abnormality and the joint may be classed as unstable. The head of the thighbone moving in and out of the socket causes this. "Clicky" sounds are not always important; a "clicky hip" can be entirely normal.

When the test shows a potential problem it is called a positive test, while a test that reveals no problem is called a negative test.

Do these tests cause my baby any discomfort?

The manipulation is very gentle and should not cause discomfort, but some babies object to being examined, however gently.

My baby's hip test is positive, what happens next?

A more senior and experienced clinician will examine your baby's hips. It is also recommended that your baby's hips have an ultrasound examination.

What is an ultrasound examination?

An ultrasound examination of the hips can pick up abnormalities of the shape of the acetabulum and head of the femur, or more movement of the head of the femur within the joint than usual. These are not always felt when the hips are tested by hand. On the other hand, the ultrasound test may be normal, when the physical examination suggested there might be a problem.

My baby's hip test is negative, but my baby has one of the risk factors.

It is recommended that your baby's hips have an ultrasound examination if there is a history of hip problems in children in your family or if your baby was in the breech position. If this examination identifies a potential problem, a more senior and experienced clinician will examine your baby's hips.

A problem has been identified with the development of my baby's hips. What happens next?

Your baby will be referred to an expert clinician, usually a Children's Orthopaedic Surgeon. Depending on the results of the tests your baby will be treated or monitored.

Why is my baby only being monitored?

Most of the minor abnormalities do not cause any problems with hip development (they are called "false positives", which means that the test has suggested a problem which does not exist). It is better to wait to see if these minor abnormalities will resolve without treatment.

What is the treatment for DDH?

The Pavlik Harness

This varies according to the severity of the problem and the treating clinician; but most babies are put into some form of abduction splintage. Abduction means spreading the legs wide apart. The splints can be made from webbing, plastic or Plaster of Paris. Positioning the legs in this way helps to stimulate the growth of the hip socket.

How can I be sure my baby's hips are growing properly?

The Ortolani and Barlow Tests are not 100% accurate. This means that sometimes there is a false alarm, when you will be told that your baby may have a hip condition. However, further tests may show that in fact she or he does not have the condition.
It also means that sometimes a problem may not be picked up even if it is present. So even if your baby has had a hip check and was found to be OK, if you think there may be a problem you should still point it out to your health visitor or GP. Do not assume that because the check was "normal", there cannot be a problem.

What signs should I look for?

The condition is not painful and there are no definite signs that your child may have a problem with hip development, but the following are associated with DDH:
- One leg appears shorter than the other
- An extra deep crease is present on the inside of the thigh
- One hip joint moves differently from the other and the knee may appear to face outwards
- When you change your baby's nappy one leg does not seem to move outwards as fully as the other one
- Your child crawls with one leg dragging.
After walking age you may notice:
- Your child stands and walks with one foot on tiptoes with the heel up off the floor. (The child walks this way in an attempt to accommodate the difference in leg length)
- Your child walks with a limp (or waddling gait if both hips are affected).

Research has shown that parents are good at detecting hip problems, but often delay seeking advice because of uncertainty, so if you are concerned talk to your Health Visitor or GP. Treatment is usually less complex the earlier it is started.

My child has had a positive diagnosis of DDH, is treatment necessary?

Untreated, developmental dysplasia of the hip may worsen throughout an individual's life and there is a risk of developing osteoarthritis of the hip at a younger age than normal. If the condition is causing shortening of the leg it is likely to cause problems with the spine, knee and ankle.

Where can I find out more information about DDH?

You should contact your medical practitioner for information relating directly to your child.

Contact the steps helpline on 0871 7170044 (national rate applies) or by email at info@steps-charity.org.uk

Externally reviewed August 2004: Published October 2004Baby Hip Health
An information leaflet produced by steps for Baby Hip Health Week. Download a copy of the Baby Hip Health leaflet from here