A, Congenital dislocation of left hip in 13-month-old infant. B, Radiographic signs of congenital hip dislocation. 1, horizontal line (Hilgenreiner line); 2, vertical line (Perkins line); 3, quadrants (formed by lines 1 and 2); 4, acetabular index (Kleinberg and Lieberman); 5, Shenton line; 6, upward displacement of femoral head; 7, lateral displacement of femoral head; 8, Y coordinate (Ponseti); 9, capital epiphyseal dysplasia (a, delayed appearance of center of ossification of femoral head; b, irregular maturation of center of ossification); 10, bifurcation (furrowing of acetabular roof in late infancy, Ponseti); 11, hypoplasia of pelvis (ilium); 12, delayed fusion (ischiopubic juncture); 13, adduction attitude of extremity.