Ultrasound a reliable alternative to x-rays for DDH screening

Clinicians can avoid exposing asymptomatic infants to ionizing radiation by substituting ultrasound for plain radiography as a reliable screening modality for developmental dysplasia of the hip (DDH).

New research showing that ultrasound can reliably diagnose hip dysplasia in 5- to 7-month-old infants allays growing concern over using radiation in very young children to detect this common congenital birth defect.

In a presentation at the American Academy of Orthopaedic Surgeons annual meeting, investigators revealed that in dozens of screenings of 5- to 7-month-old infants for DDH, ultrasound completely correlated to x-ray in all patients.

Ultrasound typically has not been used for screening children older than newborns, so plain radiography has become the imaging gold standard in screening for DDH in 6-month-old children, despite concerns over exposing very young children to ionizing radiation.

Those concerns were heightened by a recent study showing a small increased risk of cancer for children who had diagnostic radiation in infancy or whose mothers had x-rays while pregnant. The data showed ultrasound was not associated with increased risk of cancer.

To test their hypothesis that ultrasound would be effective for DDH screening in infants, the investigators prospectively screened 35 infants aged 5 to 7 months at high risk for DDH with standard anterior-posterior pelvis x-ray and bilateral nonstress hip ultrasound. Blinded orthopedic surgeons evaluated the x-rays and ultrasounds for standard measure of hip dysplasia. Thirty-four patients were deemed normal; only 1 patient was diagnosed with dysplasia, with the diagnosis being made on both ultrasound and x-ray.

“Despite the age of the patients and the appearance of the ossific nucleus in 33 hips, ultrasound provided good quality images with 100% diagnostic correlation to x-ray in all patients,” wrote the researchers. “Clinicians can avoid exposing asymptomatic 6-month-old children to ionizing radiation by substituting ultrasound for plain radiography as the DDH screening modality of choice in this age group.”

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