Treatment of DDH depends on the age of the child and is divided into three phases.
The infant with DDH is placed in a Pavlik harness full-time, except for half an hour in the morning and half an hour in the evening for bathing. The Pavlik harness directs the ball into the center of the socket. Force transmitted by the ball into the center of the socket causes the socket to become deeper and wider.
After the child has worn the harness for one week, an ultrasound test is done to make sure that the ball is sitting in the socket. Once this is confirmed, the harness is worn for six more weeks.
At that point, a second ultrasound test checks if the angles and ratios of the ball and socket are normal. If so, the child continues to wear the harness, but only at night, for another six weeks. If the ball fails to sit properly in the socket after three weeks using the Pavlik harness, use of the harness is discontinued and the child moves to the second phase of treatment.
The overall success rate using the Pavlik harness is about 90 percent, which means that only around 10 percent of children with DDH need the second phase of treatment.
The Pavlik harness method of treatment described above is ineffective for children older than 6 months. The second phase of treatment consists of putting a cast on the hips and legs.
The child is taken to the operating room and given a general anesthetic that helps his or her body fully relax. Then the hips are carefully examined. X-rays are taken to provide a closer look at the bones of the hip joint and contrast dye may be injected into the joint to examine the soft tissues — joint lining, muscles, ligaments and other structures that don't show up on an X-ray — through a test called an arthrogram. If the hip is sufficiently stable and if the ball sits in the socket and doesn't fall out, the child is placed in a cast that extends from just below the nipples to the ankle on the side of the DDH, and to the knee on the other side.
This type of cast, called a spica cast, is worn for six weeks, at which point the cast is removed in the operating room under general anesthesia and step 1 is repeated. If all is well, the child is placed in another spica cast for six more weeks. The total amount of time a child needs to spend in a spica cast varies by individual.
For information on how to care for your child during this phase, please refer to the patient education piece, Caring for a Child in a Spica Cast.
If the hip is extremely unstable — for example, if the ball is pushed out by soft tissues that have filled up the socket — a spica cast isn't enough and an open reduction of the hip is required. During this procedure:
The principal complication associated with both step 1 and step 2 is injury to the blood flow to the ball. This occurs 20 to 40 percent of the time, although how it happens is unclear. If it does occur, the head of the femur may grow abnormally and become permanently deformed. This results in arthritis of the hip. The extent of the arthritis depends on the degree of injury to the blood supply, as well as how much of the bone is deprived of normal blood flow.
By 18 months, the socket and, less frequently, the ball become deformed to the point that they need to be re-oriented or reshaped surgically. This consists of cutting the bone of the pelvis with or without cutting the thigh bone. The incision is approximately 10 to 15 centimeters long and is made at an angle across the front of the hip.
The cut bones may need to be held in their new position by metal implants that are removed once the bones have healed together, often several months after surgery. After this operation, the child typically is placed in a spica cast for six weeks.
In special cases, DDH is not diagnosed until a child reaches the teenage years. This typically occurs in girls who begin to experience hip pain while performing physical activities, such as playing sports. When X-rays are taken of the hip, they show that the socket is too shallow or too small for the ball.
In this situation, the best treatment is to cut the pelvis and reposition the socket so that it better covers the ball. Think of the socket as a hat, and the ball as a head. The hat is tilted on the side of the head, so it needs to be moved over in order to sit properly on top of the head.
Reviewed by health care specialists at UCSF Benioff Children's Hospital.