Hip ultrasound allows for early detection of developmental dysplasia of the hip (DDH), when treatment is generally simpler.
For newborns with a normal clinical examination, the Italian intersociety consensus document recommends universal ultrasound screening between the fourth and sixth week of life. [1]
When to perform it earlier
If true instability, particularly a positive Ortolani sign, is detected during the neonatal visit, the ultrasound should be performed before the normal screening window, ideally before discharge or within the first week. [1]
Indiscriminately performing the examination earlier in clinically normal newborns, however, can increase the number of hips classified as immature in the very first weeks, many of which mature spontaneously.
Clicks and Clunks
Small clicks or crepitus perceived during diaper changes or hip movements are common and do not, by themselves, indicate dysplasia. [1]
The clunk of a positive Ortolani sign is a different finding: it corresponds to the distinct sensation of the femoral head reducing into the acetabulum during the clinical maneuver.
Risk Factors
Among the most recognized factors are breech presentation, first-degree family history, and clinical instability. Female sex increases the risk, while asymmetry of skin folds alone is not very specific.
In the Italian program, these factors do not replace universal ultrasound screening. In other countries, selective strategies are used, which is why information found online is not always uniform. [1][2]
How the examination is performed
Ultrasound does not use radiation. The newborn is positioned on their side, and each hip is studied with standardized images.
In Italy, Graf's method is widely used, which evaluates acetabular morphology and the cartilaginous component through anatomical landmarks and angular measurements. Quality depends on correct positioning and the operator's experience. [1][3]
What Graf's classification means
A type I hip is mature.
A type IIa hip in the first few weeks is generally a physiologically immature hip and does not automatically require a brace. Age, morphology, and follow-up over time determine the significance of the report.
More dysplastic or unstable conditions, such as some IIc, D, III, and IV, require a pediatric orthopedic evaluation and, when indicated, early treatment.
If the report is borderline
Some immature hips are simply rechecked. True dysplasia or instability may require an abduction brace.
Follow-up serves to distinguish physiological maturation from a hip that is not developing as expected.
My baby is already 3 months old and has not had a hip ultrasound: is it too late?
Missing the recommended screening window does not mean that assessment is no longer useful. Discuss this with the baby's paediatrician and arrange evaluation without further delay. At 3 months ultrasound can still be informative; the choice of imaging depends on age, examination findings and the clinical question. As the baby grows, an X-ray may become more appropriate. [1,4]
There is no need to wait for pain or difficulty moving. If examination has identified instability or other suspicious findings, an orthopaedic pathway should be arranged promptly rather than simply booking a routine check. Early screening and assessing a baby who presents later are different situations. [1]
When X-rays come into play
In the first few months, ultrasound is particularly informative because a large part of the hip is still cartilaginous. With growth, generally after 4–6 months, pelvic X-rays gain a greater role, especially in monitoring acetabular maturation.
Ultrasound and X-rays are therefore used at different stages of development.
When an orthopedic evaluation is needed
A specialist evaluation is indicated in the presence of clinical instability, abnormal ultrasound findings, failure to mature during follow-up, significant limitation of abduction, or a significant discrepancy between clinical examination and imaging.
An isolated click without other findings does not equate to a diagnosis of DDH.
References
[1] Agostiniani R, Atti G, Bonforte S, et al. Recommendations for early diagnosis of Developmental Dysplasia of the Hip (DDH): working group intersociety consensus document. Italian Journal of Pediatrics. 2020;46:150. doi:10.1186/s13052-020-00908-2.
[2] Krysta W, Dudek P, Pulik Ł, Łęgosz P. Screening of Developmental Dysplasia of the Hip in Europe: A Systematic Review. Children (Basel). 2024;11(1):97. DOI: 10.3390/children11010097. PMID: 38255410.
[3] Graf R. Hip sonography: background; technique and common mistakes; results; debate and politics; challenges. Hip International. 2017;27(3):215-219.
[4] American College of Radiology / Radiological Society of North America, RadiologyInfo. Developmental Dysplasia of the Hip—Child. Imaging guidance according to age and clinical question.
Disclaimer: content for general informational purposes only. It does not replace an individual medical evaluation.
