Fig. 1.

This ultrasound image of a two-month-old infant’s hip (Graf type I) shows the lines used in the calculation of femoral head coverage. Acetabular width (d) is measured from the iliac line to the line parallel to it that touches the medial margin of the acetabulum. Femoral head diameter (D) is measured between lines parallel to the iliac line that touch the femoral head tangentially on either side. In this image, the medial margin of the acetabulum and the medial tangent of the femoral head are marked with the same line. In this hip, the femoral head coverage is 61%