General Information

Developmental Dysplasia of the Hip (DDH), also known as Congenital Hip Dysplasia, is a condition where the hip joint has not developed perfectly. The hip joint includes the head of the thigh bone, or femoral head, and the hip socket, or acetabulum. The entire femoral head normally sits inside the acetabulum, which should be deep enough to cover it completely. Hip dysplasia means that the hip joint is not perfectly developed. The spectrum of DDH can be anything from a socket that is not perfectly round but with a femoral head that is in the right place to a hip where the femoral head is completely dislocated from the acetabulum and needs to be put back in. DDH is fairly common and can occur in as many as 1 in 80 babies. The most severe form, hip dislocation, occurs in about 1 in 1000 babies. Dislocation is most common in the left hip, in girls, and more common in the first born girl. It is also much more common in breech babies, even if born by C-section.

Fortunately, DDH has been well studied and has excellent treatments available. The goal of treatment is to attain a perfect hip by the time the child stops growing. Anything less than this can result in early degenerative arthritis of the hip. The more abnormal the hip, the earlier the patient will get arthritis. The first step in treatment is to get the femoral head into the acetabulum. The second step is the keep it in the acetabulum and make it stable enough to stay there. The third step is to allow the acetabulum to remodel into a normal shape or if necessary, do surgery to create one.

After your baby was born and during well baby visits the nurses and doctors check his or her hips by spreading the legs and moving them around. They are checking to see if the femoral head is in the socket and if it can be dislocated. Although your baby may fuss during these tests, it is mostly because we are holding the hips firmly. We don’t actually try to dislocate the hip, just see if it will ride out by positioning the hip in a certain way. Some babies have hip dysplasia not identified until they are older. In these cases, sometimes the hip dislocates late, at other times the hip is out and we do not know exactly when it dislocated. We do know that in some babies the hip exam can be almost normal even with a dislocated hip. If at any point we are not sure of the position of the hip by physical exam, we can do an ultrasound. For babies under 3 months, ultrasound is better than x-ray because at this age, the head of the femur is mostly cartilage. Over time the cartilage turns to bone and after 3 to 4 months of age we prefer x-ray to look at the femoral head and acetabulum.

Treatment

The treatment of DDH varies according to the age of the child when it is diagnosed. For hip dislocation in babies under 6 months of age, we generally start with a special brace called a Pavlik Harness. The harness keeps the hips flexed and spread. This helps pop the hip into the acetabulum. If the harness cannot get the hips in the right position, or if they are still unstable by four weeks of age, we can use a body cast, also known as a spica cast. The baby needs to be anesthetized for this, and some babies’ hips will pop into place once they are asleep. If this does not happen, the surgeon can make a small cut in a tendon through a tiny incision in the skin to help the hip pop in while avoiding too much pressure on the femoral head. Less commonly, a bigger operation is needed, where the hip is opened to make room for the femoral head. The spica cast then keeps the hip in place.

For babies who are over 6 months at the time of diagnosis, the Pavelik Harness may no longer be able to get the hip in place. The child will usually need an anesthetic to relax some of the tendons around the hip and allow the femoral head to get into the socket. We also have to make sure there is not too much pressure on the hip joint or it can affect the growth of the femoral head. These babies are in a spica cast for three months and then braced.

For those children who are over 15 months of age when DDH is found, it may be possible to use traction and put the femoral head into the acetabulum while the child is asleep, then use a body cast to keep it there. However, most will need an operation to open the hip joint, get the femoral head into place, and make it stable. There is such a high chance that these children will also need surgery to fix their socket that we usually do everything at one time - get the femoral head in place and remodel the acetabulum. That way, there is one operation and one cast.

Whether in a Pavlik harness or spica cast, once the femoral head is in the socket and is stable, the acetabulum has to form into a perfectly round cup to provide a good surface for the child to walk on. The goal is to spread the body weight over a large enough joint area to prevent arthritis. If the child has been in a spica cast, they may need a different type of brace after the cast comes off to help the socket remodel correctly.

If the socket does not remodel correctly it is called acetabular dysplasia. In most cases the acetabulum will improve over time, and much of this improvement is done by 4 years of age. If the socket does not remodel on its own, surgery is performed to remodel the socket.

FAQ’s:

How long will my child need to wear the Pavlik Harness?

Once the hip is stable in the harness, we like to keep the hip in the socket for 6 weeks. At that point the harness may be able to come off part time. However, the acetabulum then needs to remodel, and that can take time. Our goal for bracing is to have the child out of full time bracing by the time they are pulling to stand, and then use the brace at night and during naps. After age 14 – 16 months many of the children stop tolerating the brace or simply learn how to take it off.

Will my child need a cast, and for how long?

Children who are diagnosed after the age of 6 months usually need a body cast, as do those under 6 moths who are not properly positioned with the Pavelik Harness. The duration of body casting is usually three months, with one cast change in the middle. Occasionally the hip is very unstable, or the child grows very quickly and requires two cast changes, but the vast majority of the patients do well with only one cast change (two casts) for the entire three months.

How long will it take for the acetabulum to remodel?

This will depend on how flat the socket is before treatment is begun. Some babies will have dislocation but a pretty well formed acetabulum, while others have a very flat acetabulum and need a good deal of time to remodel and make it round. For this reason, most babies require further bracing after the hip is in and stable; some are braced essentially full time, others part time. If they have not remodeled sufficiently with bracing, then we continue to follow the baby until either the socket is normal or does not look like it will remodel properly. If that happens we can remodel the acetabulum surgically.

Should my child have surgery to repair their socket?

This will depend on whether the acetabulum is showing improvement after the femoral head is in place. The earliest at which we can do surgery to repair acetabular dysplasia is around 18 months of age. This does not mean we perform the surgery at that age in all cases, only that we can if we need to. We would like to have the hip joint perfect by the time the child is school age. If the socket does not look like it will remodel well, or if x- rays show that the acetabulum has stopped improving, we can perform surgery to remodel the socket. The results of this surgery in older children is so good that some experts have recommended waiting on certain children and then doing “the big operation” when they are two or three years old.

(back to the top)