This is the first post of a two-part series that aims to educate parents about hip dysplasia, a common disorder in infants that, if not addressed early, can lead to serious problems later in life.
Many adults with hip replacements might have avoided much pain and major surgery had they simply been diagnosed with hip dysplasia as a baby. Hip dysplasia is the most common congenital anomaly, or a disorder that a child is born with. The condition usually goes unrecognized until adulthood, when people develop degenerative wear of the joint that affects their movement and quality of life. According to the International Hip Dysplasia Institute, approximately one out of six newborns will have some type of hip instability and two to 3 out of every 1,000 infants will require treatment. The good news, however, is that it can be treated easily if it is detected early in childhood.
What is hip dysplasia?
Hip dysplasia occurs when the ball-and-socket hip joint grows abnormally. This produces a mismatch between the head of the femur, or thighbone, which is normally rounded, and the acetabulum, or pelvic bone, the socket into which the head fits.
The ideal time to diagnose and treat hip dysplasia is when infants are younger than four months, when treatment—wearing an orthotic harness—is simple and effective. When detected in older babies, hip dysplasia often requires more complicated treatment, which for some may include surgery.
What causes hip dysplasia?
Several factors can contribute to the development of hip dysplasia. We know there is a genetic component because it tends to run in families and affects nine times more girls than boys. Hormones may play a role, too. It can also be a “packing,” or mechanical, issue, as hip dyplasia is associated with certain womb positions like breech presentation (when a baby is situated to be delivered buttocks or feet first). Being swaddled with the thighs together in the months after birth is a proven and preventable risk factor for developing dysplasia, and therefore is not recommended.
What happens if hip dyplasia is not detected and treated?
If hip dysplasia goes untreated and the hip dislocates, it will result in a limp and leg-length discrepancy, causing pain in early adolescence or young adulthood. Untreated dysplasia is also the most common cause of early degenerative arthritis, which can lead to hip replacement in one’s 50s or earlier. Normal hip joints do not wear with use and will seldom require a hip replacement, barring damage from conditions like hip dysplasia, traumatic injury or rheumatoid arthritis (a joint disease of the immune system).
Why is hip dyplasia usually not recognized until adulthood?
Unfortunately, hip dysplasia frequently goes undiagnosed in part because it is not painful at birth or in early childhood. And the most common and mildest form, called subtle dysplasia, where the socket is just a little too shallow, produces no symptoms at first. Kids develop normally through childhood, adolescence, and young adulthood, but as they grow older, the abnormal wear across the joint develops into early degenerative arthritis.
The next level on the severity spectrum is hip instability, and the most severe form is dislocation. One in 1,000 babies are born with a dislocated hip, where the thighbone is situated completely outside of the joint. Pediatricians are generally good at detecting dislocation, but should they miss it, parents will eventually notice a limp or difference in leg length. But by then, the child is walking and it is too late for early treatment.
How is hip dysplasia detected?
Pediatricians normally screen for this condition with a physical examination. Still, minor or subtle dysplasia is very difficult to detect with just a physical exam. That is why I strongly believe all newborns should have an ultrasound test, which is the best method of identifying hip dysplasia.
Certain countries in Europe conduct universal ultrasound screening in newborns, but current U.S. guidelines do not support it due to concerns about false diagnosis and over-treatment. Ultimately, parents should have a conversation with their doctor the risks and benefits about obtaining such a test for their newborn. Ultrasound is a low-cost and no-risk exam that could save many people from a future of arthritis pain and even hip replacement.
How can I make sure hip dysplasia gets diagnosed and treated early if my baby has it?
Look for signs. Hip dysplasia is usually symptom-free, but sometimes more severe forms cause a clicking sound in the baby’s hips as they move; asymmetry in the fat rolls of the thighs; or an uneven range of motion in the hips.
Know your family history. Tell your pediatrician if your family has a history of hip dysplasia, hip dislocation, or early hip replacement. If Grandma had a hip replacement when she was 55, which is considered young, we know that she most likely had dysplasia in her hip.
Talk to your pediatrician. Ask your pediatrician if they did a complete exam of the hips. You can also ask to have an ultrasound test performed. If asked, most pediatricians will agree to ultrasound. If the pediatrician has any doubt, they should refer your baby to a pediatric orthopedic specialist for further testing.
Stay tuned for our second post on hip dysplasia, which will discuss treatment and prevention.
Author: NYU Langone Medical Center
At the Hassenfeld Children’s Hospital of New York at NYU Langone, we understand that caring for infants, children, and teenagers is a special privilege. That’s why we partner with our young patients and their families to offer comprehensive inpatient and outpatient services and expertise. Our experts provide the best care possible for children with conditions ranging from minor illnesses to complex, more serious illnesses.