Newborns with sonographically dysplastic and potentially unstable hips: 6-year follow-up of an RCT.

Abstract

To examine the long-term outcome of early abduction splinting versus active sonographic surveillance in newborns with mildly dysplastic hips. Between 1997 and 2003, 128 newborns with mildly dysplastic and potentially unstable hips on ultrasound (43° ≤ α-angle < 50°) were randomly assigned to immediate abduction treatment or sonographic surveillance. All were invited for a radiographic follow-up at 6 years. The radiographs were analyzed by a single radiologist masked to the randomization allocation, and markers of hip dysplasia (acetabular index, center-edge angle of Wiberg) and avascular necrosis were reported. Eighty-three participants (65%) agreed to participate in the follow-up (42 participants from the treatment group). The mean acetabular index was 14.7° (SD: 5.6°) for the treatment group and 13.9° (SD: 3.9°) for the control group (mean difference: -0.8° [95% confidence interval: -2.9° to 1.3°]). Values were within normal ranges for age for all participants except for 1 female subject from the treatment group. The mean center edge was 26.6° for those treated and 26.4° for the active surveillance group (mean difference: -0.3° [95% confidence interval: -2.5° to 2.0°]). None had markers suggestive of avascular necrosis. We found no difference in radiographic outcome at 6 years of age between children allocated to initial splintage for 6 weeks and those offered active sonographic surveillance. The delayed acetabular ossification or persistent dysplasia seen in a third of infants from both groups at 1 year of age had completely resolved in all but 1 of the female subjects from the treatment group.