PC1074: Diagnosis of Developmental Dysplasia of the Hip in Premature Infants Undergoing Hip Ultrasound for Breech Presentation

Background: Hip ultrasound (HUS) is frequently done in premature infants with breech presentation at birth. This is based on studies showing increased risk of Developmental Dysplasia of the Hip (DDH) in term infants with breech presentation at birth. The objective of this study is to evaluate the rate of DDH diagnosis in premature infants born breech and undergoing HUS and compare it to the rate of DDH in premature infants undergoing HUS for abnormal physical exam or other reasons.

Methods: This is a retrospective chart review for premature infants born between 01/01/2009 and 12/31/2018 at < 37 weeks gestation who had HUS in the first year of life. The results of HUSs, diagnosis of DDH diagnosis made by an orthopedic surgeon up to 2 years of age, and treatments for DDH were manually collected. The average marginal difference (95% CI) of DDH diagnosis in premature infants undergoing HUS for breech presentation only was compared to infants undergoing HUS for other indications using logistic regression controlling for infants’ sex, gestational age and birthweight.

Results: From 2,397 infants analyzed, 89% underwent HUS for the only indication of breech presentation. The table shows summary statistics by DDH diagnosis and sex. DDH diagnosis was higher for infants getting ultrasounds for indication that included abnormal physical exam or other reasons (15.5% [41/264]) compared to breech presentation only (1.5% [32/2133]) with a difference of 11.4 (95% CI 7.4, 15.4) after adjusting for infant sex, GA, and birthweight. For infants with normal first HUS, 99.7% had no subsequent diagnosis of DDH, while 80% and 9% of those with abnormal and equivocal first HUS results, respectively, were diagnosed with DDH.

Conclusion: Premature infants undergoing hip ultrasound for the only indication of breech presentation at birth have DDH rate that is comparable to previously published rate of DDH in term infants with no risk factors. Screening these infants with physical examination alone may be sufficient. HUS could be reserved for premature infants with abnormal physical exam or additional risk factors.