Revisiting Traditional Risk Factors: Implications for Risk Stratification in Developmental Dysplasia of the Hip.

Abstract

Identifying patients at the highest risk of developmental dysplasia of the hip (DDH) is critical to the success of an efficient selective screening program. Defining and evaluating risk factors is, therefore, vital. This study was designed to analyze the relationship between classic risk factors and rates of DDH in a contemporary United States-based population. All patients presenting before 12 months of age to a single tertiary care pediatric hospital's orthopaedic department for DDH screening, with explicit medical record documentation of DDH risk factors from 2018 to 2022 were included. Classic risk factors were defined as breech presentation, female sex, firstborn status, and family history of hip dysplasia. Ultrasounds and radiographs obtained at initial presentation were reviewed to determine Graf and IHDI classifications. Reasons for referral for DDH screening were obtained from the chart review. One thousand two hundred twenty-six patients were eligible for the study. The probability of having DDH increased as the number of risk factors present for DDH increased (P<0.001). Female sex and firstborn status were found to be independent risk factors for DDH. Females were 2.5 times more likely to have DDH than males (P<0.001). Firstborn children were 1.3 times more likely to have DDH than subsequent birth-order children (P=0.048). There was no difference in the proportion of DDH in breech presenting patients compared with non-breech (P=0.511) or in subjects with a family history of DDH (P=0.16). The primary risk factor for DDH in this contemporary cohort was female sex. Female patients without any other risk factors for DDH had a 25.2% rate of DDH, significantly higher than the estimated population incidence. Fifteen percent of these patients had no notable physical exam findings consistent with DDH. Given the high rate of DDH in female patients in the absence of notable physical exam findings, universal ultrasound screening for females at the age of 6 weeks should be considered. Level IV.