What is Developmental Dysplasia / Dislocation
of the Hip?

What is the hip?
" Hip" is a colloquial term that refers to the articulation or joint between the femoral head and the pelvic acetabulum. The femur is the long bone of the thigh and contains a ball (called the "head") at its end which pivots inside the acetabulum (a cup-like structure). The acetabulum is part of the pelvis.

AAOS - DDH

What is Developmental Dysplasia of the Hip (DDH)?

Developmental Dysplasia of the hip refers to a group of disorders of the hip which result in the acetabulum and femoral head not developing in a normal fashion. This causes the femoral head to slide temporarily or permanently out of the cup which normally contains it. The word "dysplasia" actually means "improper development or formation." Roughly two to six of every 1,000 newborns have some degree of DDH.

The severity of dysplasia can range from mild to serious to severe. In the mild case, the femoral head (ball) can be moved slightly within the acetabulum (cup) with pressure from the examining physician, but returns immediately back to its normal position. A more serious from, the "dislocatable hip," occurs when the head can move out of the cup without outside force. It also falls back into place on its own. The most severe form, the "dislocated hip,' is where the head moves out of the cup on its own and can be put back only with pressure by a physician.

American Academy of Pediatrics - DDH

What causes DDH?

The exact cause of DDH is unknown, but there are several factors shown to be related to its development. First, abrnomal forces on the fetus inside the mother's womb or during delivery put abnormal forces on the hip and can lead to abnormal development. Breech delivery (when a baby is delivered rear-end first instead of the normal head first), for example, is a risk factor for DDH. Girls are born breech more often than boys and so tend to have hip dysplasia more commonly. Anything that causes cramping of the fetus inside the uterus can lead to DDH: this includes a lack of water around the baby or large birth weight.

What are the signs and symptoms?

At birth, a baby might not be able to move his or her leg outward as far as is normally possible. A child with DDH may begin to walk on time or just a few months later. Later during development, the pelvis of the child might drop when standing on the affected side. At even later states, an exaggeration in the spinal curvature in the lower back may develop to try to compensate for the abnormally developed hips.

There are things that the physician looks for to diagnose DDH. He or she can move the hip around and feel and listen for a "clunk" as the femoral head slides out of the acetabular cup (see figure). In addition, since the ball of the femur tends to migrate upward (toward the head of the baby), a decrease in length of the affected limb points to the possibility of DDH in an older patient

How is the diagnosis made?

Diagnosis is made by putting together the information gathered from talking to and examining the patient and by getting an x-ray or ultrasound study of the affected hip. This can show that the hip is dislocated or that the anatomy is not normal.

How is DDH treated?

Treatment of DDH, as with many other pediatric conditions, depends on the severity of the problem and the age of the patient.

In general, an infant less than 6 months of age who has DDH is placed into a special brace called a "Pavlik harness." This maintains the femoral head in good alignment with the acetabular cup and helps normal development of the hip take place. The harness keeps the leg flexed and turned somewhat outward. An ultrasound is checked after 2 weeks to see if the hip is stable. After stability is reached, the harness is worn for another 6 to 12 weeks.

In an infant between 6 months and 2 years of age, "closed reduction" is used. This means that the child is given anesthesia after which the surgeon manipulates the femoral head to direct it back into place. This improvement is maintained by placing a cast for a period of between 3 and 6 months.
For a baby more than 2 years of age, an open reduction is done. This means that the baby is taken to the operating room. Anesthesia is given and the hip is opened with a scalpel, and the hip is put back into place. At times, the femur may be broken in a strategic place and rotated to achieve correct alignment.

Finally surgery can be done on the pelvic cup to make sure that it completely covers the femoral head (ball).

Are there any complications of DDH I should know about?

There are certain risks associated with treating DDH. First, even with the methods outlined above, the hip can dislocate again. This happens in about 5% of call cases. Also, there may be some degree of dysplasia (abnormal development) that does not go away. This is true in 25% of treated children. Finally, attempts to put the femur back into place unfortunately can cause a temporary disruption of blood to the bone. This leads to altered development of the femoral head, a process which is often irreversible.

If my child has DDH, how will he or she do in the long run?

If untreated, DDH mostly likely leads to permanent, waddling gait (walking pattern) and hip pain. This pain usually begins between the age of 30 and 50. Early, properly treated hips may go on to have perfectly normal function.

Link back to Orthopaedic Conditions/Diseases