O2144: Incidence and Risk Factors of Delayed Detection of Hip Dislocations in Developmental Dysplasia of the Hip: A Two-Year Cohort Study

Background: Early detection of developmental dysplasia of the hip (DDH) is crucial, as it can lead to negative outcomes if left untreated or detected late. This study aimed to determine the incidence of delayed detection of DDH with frank hip dislocation (DL) and identify contributing maternal and patient factors.

Methods: A retrospective study was conducted within a large, self-enclosed population over 2 years. Patients with DDH under 3 years of age were included & divided into two groups based on age at diagnosis: <=3 months (early) and >3 months (late). All neuromuscular/syndromic DDH cases were excluded. Chi-square and multivariable logistic regression analysis (MVLRA) were used to determine differences between the 2 groups and assess odds ratios (OR) with 95% confidence intervals (CI) of late diagnosis relative to multiple factors, including fetal presentation, delivery type, birth weight, maternal age & parity, gestational age, and race.

Results: 437 patients with DDH were identified, including 265 early & 172 late detections. 21 of the late DDH were frank DL, accounting for 4.8% of all DDH & an incidence of .053 per 1000/year in this population of nearly 200,000 patients under 3yo. Notably, 45.5% of late DLs were diagnosed after age 1, and 20 of 21 cases were non-breech presentations. When comparing early DDH to late DL, chi-square analysis revealed a significantly lower percentage of breech presentations (4.8% vs 41.1%; p=.002) in the late group, & a lower frequency of Caesarean-sections in the late group (14.3% vs 58.5%; p<.001). MVLRA revealed increased OR of late DDH with vertex delivery (OR 2.86; CI 1.55-5.29; p<.001) and higher OR of late DDH in Blacks (OR 8.97; CI 2.99-26.94; p<.001). In keeping with the chi-square results, late DL had 11.92 times increased OR of vaginal delivery (CI 1.29-110.3; p<.05). Late DL required a mean of 1.29 trips to the operating room, with 1 patient requiring 3 trips & 81% requiring at least 1 trip. Of note, all 21 late dislocations had no known family history of DDH.

Conclusion: This study found that 39% of DDH cases were identified late, 4.8% being frank dislocations, and an increased OR of late DDH in Blacks. Late dislocations were predominantly associated with vaginal deliveries. This research highlights the need for comprehensive DDH screening beyond traditional risk factors. While DDH detection efforts have focused on breech presentations & positive family history, this study underscores the importance of thorough screening for all newborns.