Developmental Dysplasia of the Hip in babies
What is Developmental Dysplasia of the Hip (DDH)?
DDH is a condition where the ball and socket hip joint fails to develop normally. It can occur before birth or in the first months of life. The socket of the hip joint (acetabulum) is usually shallow and the ball (femoral head - top of the thigh bone) can be loose or completely dislocated instead of fitting snugly into the socket (the severity of the condition varies).
About 20 in every 1,000 children are born with a hip which is not stable at birth. This means that the hip may displace slightly or completely from its socket. All children in this country have their hips checked at birth, at six weeks, eight months and at two years.
Untreated, DDH may lead to pain in the hip (usually during teenage years) and the development of osteoarthritis (wear and tear arthritis) in adult life. It is therefore important to detect the condition and treat it accordingly.
Testing the hips
While all children have their hips examined, some children need the additional investigation of an ultrasound test. If a baby's hip is felt to be unstable it should be checked within 2-3 weeks by an ultrasound. Within the first 2-3 weeks most babies' hips stabilise spontaneously without the need for treatment. In a few, however, the hip stays unstable and the socket may form imperfectly. Under these circumstances children need treatment.
We know that some factors make it more likely for a baby to have an unstable hip:
- if another family member had hip problems in infancy
- if the baby is born by breech
- if there are other problems in the lower limbs.
These babies should be investigated by ultrasound when they are a few weeks old.
Treatment
Splintage may be recommended when a baby's hips fail to stabilise or when the socket is very shallow. This usually takes the form of a Pavlic harness: this keeps the baby's hips and knees flexed upwards and outwards which encourages the hips to develop more normally. The harness is usually worn for a minimum of six weeks but sometimes a longer period is necessary to allow the hip to become stable.
Follow-up
Where a baby is found to have a hip which is abnormal, it is very important to follow development carefully.
For the first three or four months assessment is by clinical examination and by ultrasound, but after this period X-rays may be more reliable in judging development. When a harness is used, the babies need to be seen and reviewed for at least two years to make sure the hip continues to grow safely.
Possible problems
Some babies have hips that are dislocated and will not go back into the socket. The Pavlic harness may fail to allow these hips to go back into place properly and under these circumstances it is usual to wait until the baby is a few months old before commencing treatment.
There is a small risk that even when a harness is used, and the hip reduces satisfactorily, that it will not prove enough to allow the hip to develop normally. Occasionally, therefore, such babies do need an operation when they are a little older to improve the shape of the socket.
Finally, there is a very small risk that the use of a splint may interfere with the blood supply to the ball of the hip joint. This may lead to some problems with growth and development of the hip and such babies need to be reviewed very carefully in case any further treatment becomes necessary.
The outcome
Although we have outlined some possible problems, it is important to remember that the great majority of children with an unstable hip at birth grow and develop normally and do not develop early arthritis.