Increase in late diagnosed developmental dysplasia of the hip in South Australia: risk factors, proposed solutions.

Objectives: To review evidence for the increased incidence of late diagnosed developmental dysplasia of the hip (DDH) in South Australia; to identify perinatal risk factors associated with late DDH in babies born between 2003 and 2009 in SA.

Design: Linkage study of data collected prospectively by the South Australian Birth Defects Register (SABDR) and the Pregnancy Outcome Statistics Unit (SA Department of Health), supplemented by medical records review.

Participants: All children born 2003-2009 in whom DDH was diagnosed between 3 months and 5 years of age and notified to the SABDR (data inclusion range, 2003-2014). Children with teratological hip dislocations and other major congenital abnormalities were excluded.

Main Outcome Measures: Uni- and multivariable analyses were performed to identify perinatal risk factors for late diagnosed DDH.

Results: The incidence of late diagnosed DDH in babies born 2003-2009 was 0.77 per 1000 live births, contrasting with the figure of 0.22 per 1000 live births during 1988-2003. Significant perinatal risk factors were birth in a rural hospital (v metropolitan public hospital: odds ratio [OR], 2.47; CI, 1.37-4.46; P = 0.003), and being the second child (v being the first-born: OR, 1.69; CI, 1.08-2.66; P = 0.023). Breech presentation was highly significant as a protective factor when compared with cephalic presentation (OR, 0.25; CI, 0.12-0.54; P < 0.001).

Conclusions: The incidence of late DDH has increased in SA despite an ongoing clinical screening program. Increased awareness, education, and avoidance of inappropriate lower limb swaddling are necessary to reverse this trend.