BACKGROUND: Breech presentation is considered one of the main risk factors for developmental dysplasia of the hip (DDH) in singleton pregnancies; however, data regarding twins are limited. The aim of this study was to evaluate whether breech presentation in twins is associated with abnormal hip ultrasound findings and to assess the influence of delivery mode, sex and gestational age. METHODS: Obstetric and ultrasound data from twin births at Frankfurt University Hospital between 2010 and 2014 were retrospectively analyzed. A total of 130 twins in whom at least 1 infant with breech presentation and both infants underwent hip ultrasound according to Graf's technique within the first 14 days after birth were included. Twins were divided into breech-breech, breech-vertex and breech-transverse groups. Hip findings were categorized as normal (Graf type Ia/Ib) or abnormal/immature (Graf type IIa or higher). Statistical analysis was performed using Fisher-Freeman-Halton exact testing. RESULTS: No infant demonstrated manifest DDH (Graf type IIc or higher). Overall, 5.4% of infants showed physiologically immature or abnormal hip ultrasound findings classified as Graf type IIa. No significant association was found between breech presentation and abnormal hip findings; however, abnormal findings were more common in the breech-transverse group compared to the breech-breech group (p = 0.037). Infants delivered via cesarean section demonstrated a higher rate of abnormal findings than vaginally delivered infants (p = 0.041). CONCLUSION: In this cohort, breech presentation in twins was not associated with an increased rate of abnormal hip ultrasound findings. The combination of breech and transverse presentation may represent a higher risk constellation. Due to the retrospective design and lack of a singleton control group, conclusions regarding a modifying effect of twin pregnancy on the occurrence of DDH cannot be drawn. LEVEL OF EVIDENCE: Retrospective cohort study. Level III evidence.
Jung et al. (Tue,) studied this question.