Periacetabular Osteotomy. The mother of all hip surgeries. A procedure that cuts the hip socket out of the pelvis to allow the the socket to be repositioned and then screwed back into place. This allows the ball & socket to move fluidly, preventing cartilage damage and preserving the joint in patients with faulty hips. The PAO preserves & enhances the patient's own hip, not replacing it with artificial parts like a hip replacement.