Developmental Dysplasia of the Hip
Also known as: Congenital Dysplasia of the Hip
Most babies’ hips are entirely normal at birth. Sometimes, however, they do not develop properly. The hip joint is like a ‘ball in a socket’: the top of the thigh (femur) is shaped like a ball and fits into a matching cup (acetabulum) on the side of the pelvis. If the ball is not secure in the cup in young infants it may slip out of place. This used to be called congenital (present at birth) dislocation of the hip (CDH). It is now always called developmental dysplasia of the hip (DDH): the baby’s hip does not stay securely in its socket. It may be out of place at birth or may slip out of place later. Sometimes the socket is too shallow to keep the ball in place. If it only slips partially it is called subluxation. If it slips completely out of the cup it is called dislocation.
Medical text written July 2018 and reviewed November 2020 by Mr MKD Benson, Emeritus Children’s Orthopaedic Surgeon, Nuffield Orthopaedic Hospital, Oxford, UK.
Although great care has been taken in the compilation and preparation of all entries to ensure accuracy, we cannot accept responsibility for any errors or omissions. Any medical information is provided for education/information purposes and is not designed to replace medical advice by a qualified medical professional.
Most importantly the hip which is not in place does not hurt in young children.
In newborns and babies DDH may be suspected if:
- one leg seems shorter than the other (although it is important to remember that sometimes both hips are affected).
- an extra, deep crease is present on the inside of the upper thigh
- one hip joint moves differently from the other and the knee may appear to face outwards
- when a baby’s nappy is changed one leg does not seem to move out sideways as fully as the other
These findings become a little more obvious in the first few months.
When the young child begins to crawl one leg may seem to drag.
After walking age the child:
- usually has a painless limp
- walks on tiptoes on one leg only as the affected leg is shorter.
- walks with a waddling gait if both hips are affected ( lurches from side to side)
Usually we do not know why a baby’s hips are out of place. It is, however, more common in babies born by breech (delivered bottom first rather than head first) and it is more common if the baby has been a little squashed inside the womb. Special care is taken in the examination of babies at birth when there is a special risk factor. It is more common in some families than others.
All babies undergo routine examination of their hips at different ages. At birth they are checked (usually by a children’s doctor) by two tests called the Ortolani and Barlow tests. The baby is laid on his or her back and the hips are gently taken sideways. If the baby’s hip does not move outwards as fully as it should or if there is a clunk (felt but rarely heard) it may be that the hip is not developing properly and further investigations are necessary. In a young baby, further investigation is by ultrasound but in an older child X-rays are more commonly helpful in making the diagnosis. Any baby whose immediate family has had DDH should have an ultrasound even if the doctor cannot feel any problem. In the same way any baby who was found before delivery to be in the breech position should have an ultrasound arranged.
The GP or clinic doctor routinely checks the baby’s hips again at 6-8 weeks as part of a general screening programme and if there is any concern will refer for an ultrasound or to a children’s orthopaedic surgeon.
Your child’s Red Book contains very useful information about DDH and it is wise to read it carefully.
Most children who have slight instability of their hip at birth will get better on their own without the need for specific treatment. It is important, however, that every baby with any concern should have an ultrasound examination within a few weeks of birth.
If developmental dysplasia of the hip is recognised early it can nearly always be treated simply by a splint which may need to be worn for 6 to 12 weeks. This keeps the baby’s hips flexed and out sideways.
For older children treatment is usually a little more difficult. Sometimes it is possible to put the hip safely into joint under an anaesthetic and hold it in a plaster cast (closed reduction). It may be necessary to release some slightly tight tendons in the groin at the same time.
If the hip cannot be put back into place an operation becomes necessary (open reduction). This too needs a plaster cast (called a spica) to ensure the hip remains in the right place (reduced).
Whenever children have been treated for developmental dysplasia of the hip (DDH) it is very important that they are carefully followed up by a children’s orthopaedic specialist for several years to make sure the hip continues to grow properly. Occasionally another operation is necessary as they grow older if the socket fails to grow properly.
Although there is no simple genetic problem we know that DDH is more common in some families and all parents are asked if anyone in the family has needed treatment.
There is no test for DDH before a baby is born – the mother’s ultrasound for example will not help to diagnose the problem before birth even though it is very helpful afterwards.
Information and support in the UK for developmental dysplasia of the hip is provided by STEPS (see entry Lower Limb Abnormalities).