Developmental dysplasia of the hip in South Australia in 1991: Prevalence and risk factors.

ObjectiveTo determine the prevalence of developmental dysplasia of the hip (DDH) in South Australia (SA) in 1991, the proportion of cases detected in the neonatal period and the perinatal risk factors for DDH.MethodologyCases of DDH born in SA in 1991 were identified from multiple sources and their clinical data linked to perinatal data provided by midwives; five controls per case were obtained randomly from SA livebirths without congenital abnormalities and adjusted odds ratios (OR) for potential risk factors obtained by logistic regression analysis. South Australia perinatal data were also used to estimate numbers of births with perinatal risk factors for targeted screening.ResultsTwo hundred and six cases of isolated DDH were identified, giving a prevalence of 10.5 per 1000 births. Of these, 173 (84%) had been detected in the neonatal period. The perinatal risk factors for DDH were identified as breech presentation (OR 9.65), female babies (OR 4.04), first births (OR 1.91) and maternal age of 25 years or more (OR 1.53). Screening breech and firstborn female babies (23% of births) would yield approximately 51% of cases of DDH.ConclusionsIsolated DDH had a prevalence of 10.5 per 1000 births and 84% of cases had been detected in the neonatal period in SA. Repeated screening during infancy of "at risk' groups of babies is recommended