Prevalence and Morphological Characteristics of the Femoral Head Ossification Nucleus in Chilean Infants: A Cross-Sectional Study.

Developmental dysplasia of the hip (DDH) affects 1-3% of newborns and requires early detection for optimal outcomes. DDH involves abnormal acetabular-femoral congruence between the acetabulum and femoral head, resulting from either shallow acetabular development or delayed femoral ossification of the femoral head. We evaluated the ossification nucleus of the femoral head (ONFH) to determine prevalence, radiographic timing, and associations with perinatal factors. We analyzed 100 pelvic radiographs of infants between 90 and 150 days of age. Participants were selected by convenience sampling, based on inclusion criteria. We identified the presence of ONFH and measured biometric parameters, morphology, and anatomical location. Sociodemographic and perinatal data were collected from the participating infants. The prevalence of ONFH was 33%, and the mean age at visualization was 104 days. The presence of ONFH was correlated with birth weight ( = 0.011), discharge weight ( = 0.005), and weight at 1 month ( = 0.034). In our study, female sex ( = 0.004) was associated with a 4.966-fold higher odds of ONFH prevalence compared to males. This study provides relevant evidence regarding the prevalence, morphology, and characteristics of ONFH. Few studies report this information on ONFH in different populations. The optimal timing for radiographic visualization of ONFH in infants remains undefined, but the appearance of the ONFH was concentrated around 104 days of life. The novel association between weight and ONFH provides new insights into DDH. This provides new insights for DDH screening. This association warrants further research for the early detection of DDH.