This patient is a young adult who had his spine fused in a flatback position due to his disease called Ankylosing Spondylitis.
The disease fuses the sacroiliac joints causing pain and fuses the spine in a forward bent position. The result was that he was unable to see in front of him and was always looking down to the ground.
He underwent a Pedicle Subtraction Osteotomy (PSO). The Pedicle Subtraction Osteotomy entails removing a wedge of bone from the vertebral body to recreate the lumbar lordosis or swayback so the patient can stand up straight and look forward.
The posterior correction was performed using a four rod technique in conjunction with the Pedicle Subtraction Osteotomy.
The multiple rods help in closure of the osteotomy and prevent rod breakage. The additional rods also help in achieving fusion and avoid revision surgery.
I have been using multiple four rod technique since 2002.
One can see the correction of the lumbar lordosis with the Pedicle Subtraction Osteotomy on the x-rays.