A sonographic study of the morphology of the preterm neonatal hip.

Preterm and low-birth-weight infants are reported to have an increased risk of late presentation of congenital dislocation of the hip (CDH). A sequential sonographic study of hip morphology was made of 82 live preterm infants. Eighty-two matched, term controls were scanned for comparison. The morphology of the hips was similar at birth. The increase in missed CDH cannot be explained in simple morphological terms. Abnormal birth sonograms resolved rapidly in the absence of clinical instability, casting doubt on the role of static sonographic appearances to predict the need for treatment in the immediate newborn period.