Intrathecal morphine prolongs post-operative analgesia, but at the expense of increasing nausea, vomiting, pruritus, urinary retention and risk of respiratory depression.
Intrathecal fentanyl prolongs post-operative analgesia at the expense of increased incidence of pruritus, but with no increase in respiratory depression.
Harrington rods are not a contraindication to epidural analgesia but do increase insertion difficulty, technique failure and complications, particularly dural puncture and subdural placement.