Infant Hip Dysplasia: A Q&A With Dr. Todd Blumberg
December 1, 2021
Dr. Blumberg is an orthopedic surgeon who works with patients from infancy through young adulthood treating all hip conditions.
About 1 in 100 babies has signs of hip instability at birth, and hip dislocations are identified in approximately 1 in 1000 newborns. Risk factors for hip dysplasia include breach position at any point after 32 weeks gestation, family history of hip dysplasia in parents or siblings and improper swaddling with the hips immobilized in extension and adduction (knees together). Females have a higher incidence of hip dysplasia than males, but sex is not considered a specific risk factor for screening purposes. In general, preterm infants are at lower risk for hip dysplasia, but should still be screened if they meet the criteria at the corrected age.
All babies are screened with clinical exams at multiple points, assessing for instability in the hips, asymmetric abduction and relative leg-length differences that could indicate that one hip is out of the socket. The most sensitive test for a hip dislocation is the Ortolani maneuver, an exam maneuver where a palpable “clunk” is appreciated as the hip reduces back into the socket in flexion and abduction. For babies with any of the risk factors noted above or an inconclusive exam, an ultrasound at 6 weeks of age is the ideal time to screen.
Breech presentation is felt to be a particularly strong risk factor for hip dysplasia, even in the setting of a normal physical exam. In addition to a screening ultrasound at 6 weeks, a single anterior-posterior (AP) pelvis radiograph at 6 months is also recommended.
We are the highest-volume center for hip dysplasia in the Pacific Northwest. Our ultrasonographers perform around 5,000 screening infant hip ultrasounds annually across all the Seattle Children’s clinical sites. While many of these screening studies are normal, I see the infants with abnormal exams and ultrasounds, as well as older children who were previously treated for hip dysplasia and need continued follow-up to confirm that their hips have developed appropriately. I also see adolescents and young adults with hip dysplasia. I probably see about 10 to 15 new hip patients each week.
We recently created a new algorithm for infant hip dysplasia to walk providers through the process of evaluating, diagnosing and referring their patients from birth to 2 years old. While this doesn’t cover all scenarios, it hopefully helps with common questions about if or when to refer.
The number of patients we get referred from across the region has increased significantly over the last few years, especially as high-quality infant hip ultrasound has become more difficult to access in many parts of the region. A lot of older children end up getting radiographs as well, especially if there is a concern about their exam or gait when the child is older. Unfortunately, many of these studies are not interpreted by a radiologist with pediatric training, leading to an increased diagnosis of possible hip dysplasia when metrics fall within a normal range for the child’s age. It can be frustrating for parents to travel with a young child only to learn the findings are normal. We want primary care providers to feel comfortable reaching out if imaging reveals concerns for hip dysplasia so we can help triage patients or even provide reassurance. A lot of reports may suggest mild dysplasia that is well within the normal range for a patient, or the radiograph may have suboptimal technique, rendering the values less useful.
It is important to remember that the metrics we utilize for determining whether hips are normal or not vary with age, and for many with mild elevations in numbers at a young age, these often spontaneously resolve as the child grows and the hip develops further.
Q: The new algorithm refers to varying degrees of dysplasia, i.e. dysplasia versus borderline/mild dysplasia and normal acetabular index. Can you describe those a bit more?
This is one of the most challenging things about treating hip dysplasia. Where there is a slight elevation of the acetabular index (~2-3 degrees), it is common to see things improve and often spontaneously resolve with time. The acetabulum can remodel up until about age 5 or so, and once kids start a weight-bearing activity, we see a rapid increase in the development of the hip socket. In order to not overtreat a condition that will improve as kids get older and begin walking, we only want to treat the kids that are truly dysplastic. For children with normal metrics, no brace or surgery is ever indicated. For infants and toddlers with mildly elevated acetabular indices, it is common to discuss options with the parents and consider treatment if there is a family history or perhaps a delay in motor milestones, but otherwise safe to observe and follow with serial radiographs to ensure improvement. For significantly abnormal numbers (usually two standard deviations above the mean) we generally recommend treatment.
One way is knowing when not to refer a patient — for example, newborns. Babies in the first day or two of life that have an abnormal physical exam for hip dysplasia in the hospital should be watched, but not referred (yet). Most of the time, newborn instability resolves on its own. We want you to continue to evaluate these hips at well-baby exams, and if their exam remains abnormal at the 2-week well-child check, feel comfortable referring them at that time for evaluation.
Screening ultrasounds can be challenging to interpret, and results determine whether early treatment for hip dysplasia is indicated. There is good data now to support that if the clinical exam is normal and a screening ultrasound is only mildly abnormal at 6 weeks of age, then it is safe to wait and recheck them later rather than referring in to evaluate. Close to 99% of the time a child with a mildly abnormal ultrasound (i.e., alpha angles between 50 and 59 degrees and femoral head coverage between 35% and 49%) in the setting of a normal exam will spontaneously resolve by 12 weeks with no intervention and hip-friendly swaddling.
Another great option is to check with us if you’re not sure what to do next.
You can email us your imaging or upload it to Powershare. We’re very happy to look and advise on the next steps. A quick call like this can save families a significant amount of time and money. It can be hard to find good pediatric imaging outside Seattle Children’s, and we realize that poses a hardship for our far-away families. But poor imaging isn’t useful and will need to be repeated.
We try to minimize clinic visits unless treatment is needed. We are cognizant that for some families, this may mean a second visit after a screening ultrasound. However, it allows us to coordinate an Orthotics visit and often prevents an unnecessary visit that costs the family time and money. It also allows us to work in those patients that have abnormal hip exams or ultrasounds that indicate treatment is needed on an urgent basis more efficiently.
Yes, you are welcome to refer families directly to our Radiology department for an ultrasound. No appointment is needed with Orthopedics. In fact, if you want just an ultrasound and you send a referral to Orthopedics, it might slow down scheduling because we will have to redirect it to Radiology (we don’t have our own imaging within Orthopedics).
Please keep in mind infants under 4 weeks do not need hip ultrasounds, and if being done for screening purposes (breech, family history), then it is recommended to be done at 6 weeks of age and corrected for any infants born <37 weeks.
We recommend re-examining them at the well-child checks after discharge from the hospital. True instability in the newborn often resolves quickly, but a dislocated hip does not. If the exam remains abnormal at the 2-week well-child check, please send in a referral marked as urgent, and we’ll work them in within 7 to 10 days and try to coordinate an Orthotics visit to begin treatment if necessary. We don’t need an ultrasound to start treatment if the exam is clearly abnormal. If there seems to be any barriers to getting the patient in for an urgent evaluation after 2 weeks of age, please contact us directly.
You’ll find the details in our new infant hip dysplasia algorithm, developed based on the clinical practice guidelines already published. Evaluation for hip dysplasia depends on the child’s risk factors, age, physical exam and imaging results. Corrected age is utilized for preterm babies born <37 weeks when it comes to timing screening ultrasounds.
Findings that are concerning at any age include:
- Limited hip abduction (unilateral or bilateral)
- Positive Galeazzi sign/leg-length difference (leg appears short in flexion)
- Positive Ortolani sign (hip reduces in abduction and flexion)
- Positive Barlow maneuver (hip dislocates in adduction and flexion)
- Gait abnormality if walking age
- Hip clicks are audible high-pitched “clicks” or “pops” that occur as soft tissue snaps or catches over bony prominences. They are common in babies and usually not of any clinical concern when there is no associated hip instability. If there is any clinical concern, however, an ultrasound or radiograph is appropriate to rule out dysplasia.
- A hip clunk, on the other hand, is a distinct feeling detected more by sensation than hearing. It is not audible and represents feeling the femoral head reducing into the hip socket with hip flexion and abduction. It’s more serious and a stronger indicator of a hip problem. We think of Ortolani-positive hips as those that “clunk” in place and warrant treatment urgently.
Treatment depends on when dysplasia is identified and how severe it is. In the first few months of life, babies often can wear a type of harness or abduction brace to fix the problem, with success rates around 80% for dislocated hips. For babies older than 6 months, bracing may be attempted if the issue is a shallow hip socket, but it is usually not successful when the hip is fully dislocated. For these children and older, surgery is often needed to stabilize the hip.