[Congenital hip dislocation. Ultrasonic screening of newborn infants].

Despite the introduction of clinical screening and early treatment of congenital dislocation of the hip (CDH), the prevalence of subluxated/luxated hips in later infancy is still reported to be as high as 1-3 per 1,000 infants. Using ultrasound, it is possible to evaluate both hip morphology and hip stability. Hip morphology is best evaluated using Graf's coronal section through the deepest part of the acetabulum. Classification of the hips into different categories can then be based on measuring the angle of inclination of the acetabulum (alpha-angle) or femoral had coverage. Hip stability can be assessed by a Barlow-equivalent provocation test during the ultrasound examination. In the Norwegian newborn population approximately 85% of the infants have morphologically normal hips (based on the alpha-angle) while 12% have immature and 3% dysplastic hips. About 80-90% of infants with dysplastic acetabula show only minor changes, and many of the hips may normalize without treatment. Several studies indicate that universal ultrasound screening might reduce the occurrence of late diagnosed congenital dislocation of the hip.