Newborn hip ultrasound is the preferred imaging test for developmental dysplasia of the hip (DDH) until the femoral head ossifies, typically through 4 to 6 months of age. The study determines whether the acetabulum is morphologically mature and whether the femoral head is stable in the socket. This guide covers positioning, Graf angles, dynamic stress testing, classification, and pitfalls that cause false positives or missed dysplasia.
When a Newborn Hip Ultrasound Is Indicated
Universal screening of every infant is not generally recommended in the United States. Selective imaging is used for an abnormal hip examination or for risk factors with a normal exam. Typical indications are a positive Ortolani or Barlow maneuver, limited abduction, Galeazzi sign, breech presentation, first-degree family history of DDH, and follow-up of an immature or treated hip.
When the exam is normal but risk factors exist, many centers schedule infant hip ultrasound at 4 to 6 weeks rather than in the first days of life, because physiologic laxity can create borderline studies. A frankly unstable hip should be imaged promptly. After about 6 months, and sometimes as late as 6 to 8 months, the ossific nucleus usually limits ultrasound, and radiographs become more useful.
Newborn Hip Ultrasound Protocol: Positioning and Landmarks
Use a high-frequency linear transducer and examine both hips with morphologic and dynamic views, consistent with AIUM, ACR, SPR, and SRU practice parameters. Scan supine or in lateral decubitus with the hip slightly flexed. Align the transducer with the long axis of the ilium so the iliac wing appears as a straight horizontal line.
The Graf coronal standard plane must show the chondro-osseous junction, femoral head, labrum, cartilaginous roof, bony acetabular roof, and a straight iliac contour. If the ilium is tilted or the labrum is not seen, do not measure. Document a rest view in that plane, a stress view with adduction and gentle posterior pressure, and the contralateral hip. Label laterality on every image. Clarify whether the request is screening or a targeted diagnostic exam, a distinction also discussed in purpose-driven diagnostic versus point-of-care ultrasound.
Graf Classification: Alpha Angle, Beta Angle, and Types
On a true standard-plane image, draw a baseline along the lateral iliac cortex, a bony roof line from the inferior iliac margin at the triradiate cartilage to the bony rim, and a cartilage roof line from that rim through the mid-labrum. Alpha is the angle between the baseline and the bony roof. Beta is the angle between the baseline and the cartilage roof.
- Type I (mature): alpha 60 degrees or greater. Ia, beta under 55 degrees; Ib, beta 55 degrees or greater.
- Type IIa (immature, under 3 months): alpha 50 to 59 degrees. After 6 weeks, IIa+ (about 55 to 59 degrees) is more likely to mature than IIa- (50 to 54 degrees).
- Type IIb: alpha 50 to 59 degrees at 3 months or older.
- Type IIc: alpha 43 to 49 degrees with the head still centered.
- Type D: alpha 43 to 49 degrees, a large beta often cited as 77 degrees or greater, and a decentering head.
- Type III: dislocated, alpha under 43 degrees, labrum displaced cranially (IIIa hypoechoic; IIIb echogenic and deformed).
- Type IV: dislocated, labrum interposed inferiorly and blocking reduction.
Femoral head coverage, when used, is often viewed as reassuring above about 50 percent, though published thresholds vary. Combine coverage with Graf type and stability. An abnormal study means deficient morphology, instability, or both, not a single angle from a tilted frame.
Dynamic Assessment
Morphology and stability are complementary. On the transverse flexion view, the femoral head should remain seated against the posterior acetabulum during gentle Barlow-type stress. Report the hip as stable, lax but reduced, dislocatable, or dislocated at rest. Avoid forceful maneuvers.
Pitfalls That Mimic or Miss Dysplasia
Most errors are technical. Standard-plane discipline matters here as it does in other musculoskeletal exams such as shoulder ultrasound protocol and technique.
- A tilted iliac wing falsely lowers alpha and overcalls dysplasia.
- If the labrum or bony rim is missing, beta is unusable and types I, IIc, and D cannot be separated.
- A plane that is too anterior or posterior can uncover the head or mistake ischium for acetabular roof.
- Excess transducer pressure can reduce a dislocatable hip.
- Calling type IIa pathologic in the first weeks, or continuing ultrasound after a large ossific nucleus appears, mismatches the method to age.
- Skipping stress views misses instability. Imaging only one hip misses bilateral DDH. Asymmetric folds are a weak indication.
Reporting Pearls
Include indication, age in weeks, and prior treatment. For each hip, report alpha, beta, Graf type, coverage if used locally, stability, and any ossific nucleus. Compare sides and suggest follow-up imaging or orthopedic review according to institutional practice. Do not prescribe treatment for an individual infant. Management belongs with the referring clinician and current orthopedic guidance.
IAME offers accredited ultrasound CME courses on musculoskeletal scanning technique, measurements, and reporting.
Frequently Asked Questions
Why would a newborn need a hip ultrasound?
Imaging is used to evaluate DDH when the hip examination is abnormal or when risk factors such as breech presentation or a family history of dysplasia are present. Ultrasound shows cartilage and the unossified femoral head, which radiographs cannot. In most U.S. practices it is a selective test, not a replacement for the newborn hip exam.
How long does an infant hip ultrasound take?
A cooperative infant can be scanned in about 5 to 15 minutes, including both hips and stress views. A warm room, feeding, and a parent holding the upper body shorten the study. Fussiness or extra documentation of an unstable hip can extend the appointment.
What are the early signs of hip dysplasia in babies?
Examination clues include a clunk on Ortolani, a dislocatable hip on Barlow, limited abduction, and apparent leg-length discrepancy. Asymmetric thigh or gluteal folds are common and nonspecific. Sonographic signs include a low alpha angle, high beta angle, poor coverage, and a head that subluxates or dislocates with stress.
Do babies outgrow hip dysplasia?
Physiologic immaturity, especially Graf type IIa in the first weeks to months, often progresses toward a mature type I hip on follow-up. Established dysplasia, decentering, and dislocation do not reliably resolve without treatment. Follow-up should follow current orthopedic guidance rather than an assumption that the hip will normalize on its own.
