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The incidence of true developmental dysplasia of the hip (DDH) — a hip that is dislocatable or has persistent or severe dysplasia — is estimated at 3 to 5 per 1000 newborns. However, many more newborns have mild hip instability on physical examination or mild dysplasia on hip ultrasound (US). Initial management options for mild dysplasia are abduction splinting or observation with follow-up US. To compare these two approaches, researchers in Norway randomized 128 newborns with US-detected mild dysplasia (α angle, 43–49 degrees) to immediate splinting or active surveillance. At the study institution, newborns with clinically abnormal hips and newborns with risk factors for DDH (breech presentation or family history of DDH) routinely undergo US. Infants with smaller α angles (more-severe dysplasia) or clinically dislocatable or dislocated hips were excluded.
Pediatric radiologists who were blinded to the infants' treatments repeated US at ages 6 weeks and 3 months, and splinting was initiated, continued, or discontinued at these times based on the degree of dysplasia. Thereafter, management was dictated by subsequent US findings (α angle) in splinted infants and by plain radiograph findings (acetabular index) in all infants at age 6 months. No children were lost to follow-up.
At both 6 weeks and 3 months, infants in the immediate-splinting group had better US α angles than the active surveillance group. However, at age 12 months, plain radiographs showed no statistically significant differences between the two groups: The immediate-splinting group (64 children) and the active-surveillance group (64 children), respectively, had 7 and 4 children with hip dysplasia, 19 and 20 children with delayed acetabular ossification, and 38 and 40 children with radiographically normal hips. The median duration of abduction splinting was 12 weeks in both groups, and 47% of infants in the active-surveillance group were splinted at some point. The active-surveillance group had a higher percentage of girls, but no sex differences in measurements or outcomes were found at follow-up.
Rosendahl K et al. Immediate treatment versus sonographic surveillance for mild hip dysplasia in newborns. Pediatrics 2010 Jan; 125:e9.
Comment
Abduction splinting (e.g., with a Pavlik harness) can make breast-feeding, diaper changing, and even bonding difficult. Rare complications, such as femoral nerve compression and avascular necrosis of the femoral head, can also occur. This relatively large randomized trial with complete follow-up confirms that newborns with mild dysplasia on hip US can be observed without splinting for the first 6 weeks. This approach obviously does not apply to newborns with clearly dislocatable hips on physical exam or more-severe dysplasia on US, for whom the benefits of splinting are proven. However, for populations in which risk factor–based US screening identifies more newborns with mild dysplasia, this surveillance approach will avoid much unnecessary early splinting.