Spinal surgery. Image 1 of 3. Close-up of surgery on the spine of the neck to correct ankylosing spondylitis. This cervical osteotomy involves the removal of part of a vertebra of the spine, exposing the spinal cord (centre). Retractors (silver) hold the area open. Bolts seen in the vertebrae will have rods placed between them to hold and support the spine. Spinal cord nerve impulses are monitored to ensure no damage occurs. Ankylosing spondylitis is an inflammatory disease of the joints between the vertebrae, causing back stiffness and a curved posture. See images M551/267-269 for a sequence of the operation.