Figure 1 Surgical procedure of periacetabular osteotomy (PAO) demonstrating key osteotomy steps in lateral decubitus and supine positions (Neusoft Medical image diagnostic reporting system; Neusoft Co Ltd, Shenyang, China). (A) The lateral decubitus position: the osteotome was used to truncate the anterior half of the ischium along the direction of the inferior acetabular groove. (B) The supine position: the pubic double tip bone chipper, quadrilateral, ilium, and periacetabular osteotomy were performed to connect with the ischium osteotomy. The iliac bone block was inserted into the osteotomy gap. The anterior superior iliac spine was reduced and fixed with cortical bone screws. (C) Anteroposterior schematic view of the pelvis.