USMLE Step 2 Clinical Knowledge (CK) Practice Exam

Developmental dysplasia of the hip (DDH) is a condition where the hip joint does not properly form in infants and young children. The most commonly affected demographic includes white females who are first-born and may have been in a breech position during delivery. This demographic is frequently highlighted in the literature due to various factors, including genetic predisposition and environmental influences that contribute to the development of this condition.

White females are statistically more likely to have DDH compared to males and other ethnic groups. Additionally, being first-born may increase risk due to factors like uterine space constraints and fetal positioning during late pregnancy. Breech presentation, where the baby is delivered feet first instead of head first, has also been associated with a higher incidence of hip dysplasia as it may lead to improper positioning of the hip joints during crucial development stages.

Understanding these risk factors is important for early detection and management of DDH, which can lead to better outcomes for affected children. Thus, the combination of these factors in the correct answer makes it the most accurate representation of the demographic commonly impacted by this condition.