What’s Hip Now in Developmental Dysplasia

Keeping up with fashion trends is hard. There’s likely to be a difference of opinion as to what constitutes a “hip” style. It’s only fitting, then, that when a baby is found to have a possible hip problem—this time, we’re talking about that body part where the leg meets the trunk—that members of the medical community might differ in their approach.

Such is the case when we’re dealing with a condition known most commonly as developmental dysplasia of the hip (often abbreviated DDH), a condition commonly found in infancy. In order to address the differences that providers might have in how they diagnose and treat the condition, let’s first examine what DDH is.

The best way to describe DDH is to talk about the hip joint, which consists of a “ball”—more properly, the head of the femur, or thigh bone—and a “socket”—the acetabulum, part of the pelvic bone. In most humans, the two bones fit together securely. However, in at least 5 percent of babies the bones are “loose” or unstable: the ball has a tendency to come out of the socket. It’s not well understood why this happens, but it appears to be at least in part due to the ligaments, which hold the bones together, being a little too flexible.

What we do know is that it happens more often in certain babies. Babies born breech have the problem more often. So do girls, first-born children, and those with another family member who has had DDH.

We’ve now talked a little bit about what DDH is and who gets it. Let’s talk a little bit more about numbers. Although, as we’ve seen, it’s fairly common for babies to have some hip instability, a smaller number (about 1 in 1000) will have severe DDH. This is a problem because if untreated, it can lead to complications such as walking difficulty and even arthritis in adulthood. Virtually all providers would treat severe DDH. It’s with the more common milder degrees of hip instability that you might get different answers on what’s “hip” to do in terms of diagnosis and treatment.

Diagnosis—Click vs. Clunk

One thing that providers agree on is the importance of the hip examination, which begins in the newborn period and is performed at every infant physical. The provider will flex the baby’s thighs and turn them inward and outward in an attempt to feel abnormal movement of the femur head or “ball.” This is known in medical-speak as the not terribly scientific-sounding “clunk.” (You might also hear the word “click” being used, but that’s more commonly used to mean a normal snapping sound that we can all hear at any joint from time to time.) The provider will also look for other clues, particularly in older infants, such as the legs not being symmetrical, or difficulty moving at the hips to begin with.

It’s where to go from this point that physicians often differ. It’s known that particularly with newborns who have an abnormal exam, many hips will “tighten up” and be just fine. Others may go on to have problems. Treatments are effective, but each has its own small risk of complications, such as interruption of the blood supply to the thigh bone. How to decide?

A provider will be more likely to proceed to the next step if the exam is very abnormal or if there are any of the risk factors discussed above. In that case she may order a hip ultrasound, which gives more information on any abnormalities. In the case of multiple risk factors (such as being a breech female), a physician may screen with an ultrasound even with a normal exam. If the infant is older than 4 months of age, a plain x-ray is more commonly done than an ultrasound.

Deciding on Treatment

Good treatments abound for this condition. A young infant will generally be placed in a device that keeps the hips in the proper position; the thighs are turned outward. The most common of these is known as a Pavlik harness, although there are other, similar devices. An older infant may need to be placed in a cast. Outside of infancy, surgery is usually required.

However, treating mild cases in young infants may be “out of fashion,” as it were, for some providers. Such infants would be followed very closely to make sure any potential hip instability resolves.

So…Who Gets What?

It’s a given that an infant will get a hip exam at every physical appointment. It’s what constitutes enough of a risk to the baby (versus the risk of treatment, x-ray—and, if you live where I do, the three-hour drive to the ultrasound department!) that will influence a provider’s recommendations. Many will recommend seeking advice directly from an orthopedist who treats DDH frequently. By the same token, if it’s decided to get an ultrasound, they’ll look for specialists who ultrasound a lot of baby hips.

There are definitely some “hip” things you can do for your baby. Knowing that DDH exists is one thing. Having a dialogue with your provider about your little one’s examination and informing him of any risks (such as family history of DDH) are a couple of other important actions. DDH can be a big problem if untreated, but working together, you can help to ensure hip health—and that’s always in fashion!

Stan Sack
Dr. Stan Sack has 29 years’ experience as a primary care pediatrician in Massachusetts and Florida. A medical writer since 2015, he enjoys blogging on topics that are on parents’ minds but are covered less often in books and on websites. He lives in the Florida Keys with his family and enjoys healthy cooking, fitness activities and singing in his spare time.

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