In this study, surgeons from Turkey ask the question: is the level of surgeon experience linked to decisions made regarding second surgeries for hip dysplasia in children? In other words, are the more experienced surgeons more (or less) likely to perform a second procedure in children with this problem? Or is it the less experienced surgeons who opt for second surgeries. Let’s see why that question is important and what they found out.
First, a little bit of background information about developmental dysplasia of the hip or DDH. This condition used to be known as congenital hip dysplasia. The change in name reflects the fact that DDH is a developmental process that occurs over time. It develops either in utero (in the uterus) or during the first year of life. It may or may not be present at birth.
In this condition there is a disruption in the normal relationship between the head of the femur (thigh bone) and the acetabulum (hip socket). DDH can affect one or both hips. It can be mild to severe. In mild cases called unstable hip dysplasia, the hip is in the joint but easily dislocated. More involved cases are partially dislocated or completely dislocated. A partial dislocation is called a subluxation.
Most of the acetabulum is cartilage at birth. The right amount of pressure and contact between the surfaces of these two parts helps make sure the hip joint develops normally. The head of the femur inside the acetabulum helps shape the joint as it continues to form. In DDH the usual contact between the femoral head and the acetabulum is disrupted. An abnormal position of the femoral head can result in a dysplastic hip. Sometimes the acetabulum is too shallow or sloping rather than a normal cup shape. It cannot hold the femoral head in place.
If the problem is not diagnosed and treated early, the soft tissues around the hip start to stretch out. There can be changes in the blood supply to the hip. Surgery to reshape the hip socket and reposition the head of the femur in the socket is usually done early in the child’s life. For some children, that is all that is needed. They develop normally and achieve skeletal maturity (full bone growth) without further problems.
But for others, avascular necrosis (AVN) (loss of blood to the hip) develops. Other problems that can occur over time include recurrence of the dysplasia, subluxation, or redislocation. These kinds of problems tend to show up when children are between the ages of five and eight. The challenge becomes identifying when a child needs a second surgery to maintain good hip alignment and when it is a watch-and-wait situation because the problem can correct itself over time.
Looking back over cases when the children are grown and skeletally mature and evaluating the results is one way to study this problem. Evaluating individual risk factors (e.g., surgeon experience) in making the decision helps identify ways to improve results.
There were 17 children with DDH in the study with a total of 21 hips surgically corrected before the age of 18 months. None of the children had a second surgery. All reached skeletal maturity with only the first corrective surgery. Twenty independent surgeons (they had nothing to do with treating these children) conducted the evaluation. They reviewed patient records and X-rays including mid-term and final outcomes. They compared the results against the level of the surgeons’ experience who made the mid-term decision whether the child needed a second surgery or not.
They found there was a 12 per cent risk that hips would need a second surgery that in fact turned out to be normal at the end of the growth cycle. If surgery had been done, it would have been unnecessary. Performing a second surgery was not needed in this group — even when it looked like it might be necessary during that five to eight year old age span. There was also a 40 per cent chance that surgery would not be performed on a group who should have a second surgery. This group would go on to develop hip dysplasia by the time the bones matured fully.
Although more experienced surgeons are less likely to perform surgery (and more likely to recommend conservative care), the level of surgeon experience was not linked to the decisions made in these 17 cases (21 hips).
Surgeons do not make decisions about second surgeries for hip dysplasia without specific reasons. X-ray findings of hip angle, slope of the hip socket, and the amount of femoral head covered by the acetabulum (socket) are just some of the factors taken into consideration when making the decision about a second surgery. Knowing that the top of the femur stops growing around age 10 but the acetabulum (socket) continues to develop until the child reaches full skeletal maturity also weighs in on the decision.
Surgeons know that if the head of the femur remains spherical in shape (nice and round) and stays firmly inside the hip socket by age eight, it is likely that the child will have normal hip development when fully grown. But they also know that a child can look good on X-ray at that mid-term check up and still develop hip dysplasia during their teen years. Again, that’s because changes can occur in the growth and shape of the acetabulum right up until skeletal maturity.
The surgeons who conducted this study offer their opinion on this decision dilemma. They say it is better to delay the second surgery when there is no sign of blood loss or hip instability at the mid-term point. There is no way to tell with 100 per cent accuracy from the X-rays whether this is the right decision or not.
The most challenging cases are those that have X-ray changes close to abnormal but still within “normal range.” There is general agreement from studies and from consensus of surgeons based on experience that the acetabular index angle or AIA (as seen on X-rays) is the most reliable guideline at this time.
The authors conclude that this was a study with a small number of hips involved. More study is needed to clearly identify ways to predict the need for a second surgery during the mid-term developmental stage (ages five to eight). Further study may be able to pinpoint predictive factors of prognosis to help guide surgeons’ decisions about second surgeries for children with developmental dysplasia of the hip.