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The purposes of this study were to determine the interobserver and intraobserver reliability of ultrasound measurements in unstable neonatal hips treated with the Pavlik harness and to determine whether ultrasound measurements correlate with radiological outcome at 6 months. Sixty-four babies treated from birth with the Pavlik harness for neonatal hip instability were scanned at 2 and 6 weeks. The alpha and beta angles of Graf, the combined (H) angle of Hosny, and the femoral head coverage (FHC) were measured by 3 observers and remeasured by each observer on a minimum of 50 scans. From 248 scans, 792 sets of measurements were made. Hips were categorized as normal, abnormal, or borderline for each parameter; and interobserver and intraobserver repeatability coefficients and Kappa values were calculated. The alpha angle had the smallest interobserver range (17 degrees), the H angle range was 21 degrees, and the beta angle 28 degrees. Kappa values were best for the FHC and beta angle (0.66-0.8). The mean acetabular index (AI) of all hips at 6 months was 26 degrees (SD, 4.9). The AI was 30 degrees or greater in 24 hips (18 babies) despite prolonged splintage in 9 hips (6 babies). A stepwise linear regression analysis showed that the FHC at 6 weeks was predictive of AI at 6 months (regression coefficient -0.27; 95% confidence interval -0.42 to -0.12; P<0.001). We recommend the FHC as being reproducible, useful, and predictive of outcome in neonatal hips treated for instability.

We report on seven developmental hip dislocations in five babies (age 6-22 months) in whom ultrasound had demonstrated reduced and stable hips. Four hips in three babies had been diagnosed as having clinical instability (Barlow positive) at birth, which had stabilized by the time of the scan (16-45 days). Femoral head coverage ranged from 36 to 56%. One hip had minimal sonographic laxity on stress examination. Hips that are reduced and stable sonographically at 2-6 weeks of age can subsequently dislocate. Any child with instability at birth should be reviewed with a pelvic radiograph at 4-6 months, even if an ultrasound scan appears to be normal.

This article reports the results of a neonatal hip screening program comprising clinical screening and targeted ultrasound performed by orthopaedic surgeons. Over 7 years, from 1995 to 2001, there were 15,397 live births in the authors' region. Seven hundred thirty-three babies (4.8% of births) were referred for hip ultrasound: 80% for risk factors and 20% for instability. Eighty-three babies (5.4/1,000) were splinted in a Pavlik harness. Three of these subsequently required surgery (1.9/1,000). Ten patients (0.65/1000) presented with hip dislocation after 12 weeks of age, nine of whom required open or closed reduction (0.56/1,000). From 1978 to 1985, when neonatal pediatricians clinically screened all babies, 18 babies presented late from 13,707 births (1.3/1000). Since the introduction of orthopaedic screening and targeted ultrasound, there has been a significant reduction in late diagnosis in the authors' institution.