Written by Hannah Harp
Spoon Feed
Hip ultrasound has very high negative predictive value (NPV) and high positive predictive value (PPV) for detecting developmental dysplasia of the hip (DDH) in preterm infants (GA<37 weeks).
Hip to be scanned
DDH is an underdevelopment of the acetabulum, which causes issues with joint stability, gait, pain, and joint degeneration. Detecting DDH as early as possible in infancy is a priority for pediatricians, because the earlier it is detected, the more likely the issue can be corrected non-invasively. In term infants, serial hip exams are performed, and any infant with an abnormal exam or major risk factor for DDH (e.g. breech presentation) is referred for ultrasound or X-ray. There are no clear guidelines for screening in preterm infants, even though their hips are less mature at the time of clinical exam and hip ultrasound.
This retrospective study examined whether the first hip ultrasound predicted DDH diagnosis in 2,397 preterm infants. Hip ultrasound had high diagnostic accuracy, with sensitivity of 0.91, specificity 0.99, PPV 0.80, and NPV >0.99. Among infants with DDH (n = 71), 58% were treated nonoperatively, while 36% required surgery. Equivocal HUS results led to DDH in 9%, underscoring the importance of follow-up in these cases. The study specifically pertains to preterm infants. While the paper includes descriptive data about post-menstrual age of the infants at time of ultrasound, as well as the distribution of infants from 32 to 37 weeks gestation, it will be helpful in future studies to have some analysis of these data to determine ideal timing for hip ultrasound.
How does this change my practice?
My major take-home from this study is that ultrasounds are more likely to be equivocal in pre-term babies, so extra care should be taken to follow up those ultrasounds meticulously.
Source
The Relationship between Hip Ultrasound Result and the Diagnosis of Developmental Dysplasia of the Hip in Premature Infants. Am J Perinatol. 2025 May 8. doi: 10.1055/a-2592-0430. Epub ahead of print. PMID: 40267978
