Infants can (and should) be tested early and treated for developmental dysplasia of the hip (DDH). DDH represents a group of hip disorders involving partial or complete dislocation of the femoral head. The femoral head is a round ball of bone at the top of the femur or thigh bone. Normally, it fits inside the acetabulum (hip socket). But with DDH, the femoral head slips partially or completely out of the socket.
Over the last 25 years, the treatment program for this problem has changed. In this study, pediatric orthopedic surgeons who have been following children with DDH report on how successful these changes have been in improving outcomes.
They were able to review patient charts for two groups of infants (all younger than six months old) with reducible hips. Reducible means that the dislocated hip can be put back in place with the right maneuver (hip movement). The first group was treated during the 10-year time span between 1984 and 1994. The second group was seen between 1997 and 2007.
All children were treated at the Rady’s Children’s Hospital in San Diego, California. The earlier group was treated with a Pavlik harness full-time for at least three months. The Pavlik harness holds the child’s hips and knees in a position of flexion. The hips are also abducted (held wide apart).
While wearing the harness, the child cannot straighten the legs, which means he or she cannot extend the hip. The goal is to keep the femoral head in the socket and keep it from shifting or slipping out of the acetabulum. Studies show that it works — but maybe not good enough. One-third up to 40 per cent of the children still dislocate the hip when out of the harness. They need surgery to correct the problem.
In an effort to improve results, the authors of this study added a step to the treatment. The second group (starting in 1997) was also given the Pavlik harness first. But if the hip was still unstable after three weeks, they were put in a hip abduction orthosis. The orthosis is a special brace that is semi-rigid. It holds the hips in the same position as the Pavlik harness but with less wiggle room for the leg to move and the hip to slip out of joint.
The main reason this second step was even possible was because of improved technology. In the first group, only clinical exam and X-rays were used to check the stability of the hip. If the harness couldn’t keep the femoral head in the socket, then it was discontinued and usually surgery was done next.
But office-based ultrasound studies became possible making it much easier to confirm the position of the hip early on. The ultrasound could be done with the child in the harness. Using serial (weekly) ultrasound studies, they found that if the hip was going to stabilize in the Pavlik harness, it did so in the first week of wear.
The child still wore the Pavlik harness 23.5 hours a day for the next three months. It was removed only to bathe the child. If the hip(s) remained stable, then the time on could be slowly reduced until the child was only wearing it at night and for naps. After another couple of months, it could be discontinued altogether.
For children who were switched from the Pavlik harness to the abduction orthosis, weekly clinical and ultrasound exams were still done. When it was clear that the hips were stable, then the children were put back into the Pavlik harness. Surgery to correct unstable hips was scheduled after four to five weeks of treatment for the second group. That was much sooner than for children treated in the earlier (first) group.
The results of the new treatment protocol (group 2) were significantly better than the old (group 1). The success rate went from 85 per cent up to 93 per cent. At the same time, the number of children needing surgery went down by half. The authors say that the success of their treatment depends on several key factors.
The parents must be on board with the treatment. If they don’t use the harness (and use it properly), the chances that treatment will succeed go way down. Both the Pavlik harness and the abduction orthosis (when needed) must be in good condition. This is essential to hold the hips properly in place.
Normal growth and development is possible by properly applying and using the Pavlik harness. Treatment errors are reduced with early detection of continued instability. Keeping the harness on for too long and especially with the hip in the wrong position can cause further complications.
In fact, the head of the femur can get lodged outside of the socket and stuck to the back of the hip capsule. In the hip, the capsule is a group of strong ligaments that help hold the hip in place. Without an ultrasound to show the position of the hip, this kind of condition can go unnoticed and untreated.
They suggest serial in-office ultrasound imaging for all children who have a dislocating hip that can be reduced (put back in place by hand). This has been very helpful in showing them that some children need to wear the harness longer than others. The child may not need the abduction brace, but if there is some laxity (looseness) in the joint, then three months of harness wear may not be long enough. Ultrasound testing makes it possible to identify children who need extended time in the harness.
Ultrasound can be used right at birth for infants at risk or with suspicious clinical findings. It is safe, does not expose the child to radiation, and seems to be well-tolerated. Such an early diagnosis makes it possible to achieve better results with less intervention.
Another potential problem could be ligaments that are too loose so that even with the Pavlik harness, the result would not be good. That child needs the semirigid brace. The use of ultrasound makes it possible to see these things quickly and make necessary changes in the treatment approach.
One other benefit of in-office ultrasound evaluation is the ability to monitor the child wearing the abduction orthosis for a condition called avascular necrosis (AVN). This is a loss of blood supply to the femoral head that causes the bone to die. The authors note that none of the children in either group of this study developed AVN. That’s an important result because other studies have reported rates of AVN as high as 40 per cent in the children who had to have surgery.