What Is the Proportion of Late-developing DDH After a Normal Ultrasound in Newborns With Breech Presentation?

Ultrasound at 2 to 6 weeks of age is routine clinical practice in neonates at high risk; however, developmental dysplasia of the hip (DDH) may develop after a normal screening examination. There is a current lack of consensus regarding the use and most appropriate timing of subsequent imaging.

(1) What proportion of neonates with a breech presentation who had a normal screening ultrasound result for DDH developed DDH at 6-month follow-up? (2) Are patient factors (sex and concomitant congenital muscular torticollis) associated with an increased odds of late-developing DDH?

Between January 1, 2016 and July 1, 2025, a total of 367 infants with breech presentation were evaluated by the pediatric orthopaedic service for the possibility of DDH. During that time, we recommended screening ultrasound at 6 weeks of age. The American Academy of Pediatrics and the American Academy of Orthopaedic Surgeons guidelines advise ultrasound at 2 to 6 weeks of age in infants with normal clinical examinations but elevated risks, including breech presentation. Seventy-six percent (280 of 367) of patients had a 6-week ultrasound performed; the mean ± SD age at imaging was 7.1 ± 2.0 weeks. Of those, 87% (243) were normal (defined as an alpha angle of ≥ 60° and femoral head coverage of ≥ 50%). During the study period, we recommended a follow-up ultrasound or plain radiograph at 6 months for all patients with normal ultrasound results. Of the 243 patients with normal ultrasound results, 57% (139) had a 6-month AP pelvis radiograph at a mean age of 6.7 ± 0.8 months. Binary logistic regression with a Firth correction was used to assess the odds of late-developing DDH by sex and concomitant congenital muscular torticollis.

The presence of late-developing DDH was 9% (13 of 139; 11 patients with acetabular dysplasia, 2 patients with hip dislocation). Eight of 13 patients were treated with abduction orthosis, two with closed reduction and spica casting, and three were monitored with serial radiographs. In regression analysis, female sex was associated with greater odds of late-developing DDH compared with male sex (OR 5 [95% confidence interval (CI) 1.2 to 48.0]; p = 0.03). Congenital muscular torticollis was not associated with increased odds of late-developing DDH (OR 3 [95% CI 0.9 to 10.0]; p = 0.06).

These findings demonstrate that hip dysplasia can develop after birth, which supports its developmental rather than purely congenital origin. Clinicians should consider routine follow-up imaging at approximately 6 months for infants with breech presentation, even after a normal screening ultrasound result. This approach may be particularly important in female infants, who exhibited higher odds of late-developing DDH in our cohort. However, given the modest sample size and the restriction to newborns with breech presentation, these results cannot be generalized to universal follow-up imaging for all screened populations. Targeted monitoring of higher-risk groups may allow earlier diagnosis and treatment while avoiding unnecessary imaging. The timing of follow-up radiographs and the appropriate endpoint for surveillance after a normal ultrasound result remain to be established.

Level III, diagnostic study.