False-positive sonographic hip examinations in newborns with congenital varus deformity of the proximal femur.

In cases of congenital varus deformity of the proximal femur, the screening of hip dysplasia can lead to misinterpretations. The false-positive ultrasound result is caused by the superiorly displaced greater trochanter in hips with coxa vara, which narrows the scan window. In this paper three typical patients are presented to demonstrate that the use of additional non-standard views cannot exclude hip dysplasia in all cases. Hence, such patients with femoral abnormalities and doubtful sonographic findings should be further evaluated by arthrography or magnetic resonance imaging to rule out additional hip dysplasia.