CE angle: the angle between the vertical line over the center point of the femoral head and the lateral edge of the acetabulum. In 1939, Wiberg first used the measurement of CE angle to evaluate the relationship between the femoral head and the acetabulum, and concluded that the CE angle is normally >25°, if <20° has pathological significance. Acetabular dysplasia was considered. Acetabular index: On the orthopantomograph of both hips, draw a straight line through the apex of the Y-shaped cartilage of both acetabulae and extend it, then connect a straight line from the apex of the Y-shaped cartilage to the most prominent point of the lateral upper edge of the acetabulum, and the angle between this line and the pelvic level is the acetabular index. The normal angle should be less than 30°. If it is greater than 30°, congenital dislocation of the hip joint or acetabular dysplasia may exist. Tnnis acetabular roof tilt angle: draw two straight lines through the inner lower edge of the weight-bearing zone of the acetabular roof: one passing through the outer edge of the acetabular roof and the other parallel to the horizontal axis of the pelvis, the angle between the two lines is the Tnnis acetabular roof tilt angle. Normal value: 0° to 10°. ＞The greater the angle, the worse the stability of the hip joint; <0° indicates that the acetabulum has a tendency to overcover.