Landmarks of standard anteroposterior radiograph of hip. 1, Iliopectineal line beginning at greater sciatic notch of ilium and extending down to pubic tubercle. 2, Ilioischial line formed by posterior four fifths of quadrilateral surface of ilium. 3, Radiographic teardrop composed laterally of most inferior and anterior portion of acetabulum and medially of anterior flat part of quadrilateral surface of iliac bone. 4, Roof of acetabulum. 5, Edge of anterior lip of acetabulum. 6, Edge of posterior lip of acetabulum.