Abstract

One hundred and fifty infant hips were studied using simultaneous ultrasonography and radiography. The reliability of measurement was found to be similar for alpha angle and d/D ratio. However, the acetabular index correlated much better with the d/D ratio than with the alpha angle. In fact, in hips where the d/D ratio exceeded 56%, radiographs could be dispensed with. Besides, the use of a sector scanner or a linear-array tranducer was found to make no significant difference to the correlation between the acetabular index and the d/D ratio. Sonographic assessment of acetabular development in the infant should permit a reduction in the number of radiographs required during screening and follow-up.