In addition, spinal fusion itself, particularly if more than one spinal level is operated on, may result in "adjacent segment degeneration". This is thought to occur because the fused segments may result in increased torsional and stress forces being transmitted to the intervertebral discs located above and below the fused vertebrae. This pathology is one reason behind the development of artificial discs as a possible alternative to fusion surgery. But fusion surgeons argue that spinal fusion is more time-tested, and artificial discs contain metal hardware that is unlikely to last as long as biological material without shattering and leaving metal fragments in the spinal canal. These represent different schools of thought. (See discussion on disc replacement infra.) Another highly relevant consideration is the increasing recognition of the importance of "chemical radiculitis" in the generation of back pain. A primary focus of surgery is to remove "pressure" or reduce mechanical compression on a neural element: either the spinal cord, or a nerve root. But it is increasingly recognized that back pain, rather than being solely due to compression, may instead entirely be due to chemical inflammation of the nerve root. It has been known for several decades that disc herniations result in a massive inflammation of the associated nerve root. In the past five years increasing evidence has pointed to a specific inflammatory mediator of this pain.
It can result in chronic pain and disability, often with disastrous emotional and financial consequences to the patient. Many patients have traditionally been classified as "spinal cripples" and are consigned to a life of long-term narcotic treatment with little chance of recovery. Despite extensive work in recent years, FBS remains a challenging and costly disorder. Opioids
A study of chronic pain patients from the University of Wisconsin found that methadone is most widely known for its use in the treatment of opioid dependence, but methadone also provides effective analgesia. Patients who experience inadequate pain relief or intolerable side effects with other opioids or who suffer from neuropathic pain may benefit from a transition to methadone as their analgesic agent. Adverse effects, particularly respiratory depression and death, make a fundamental knowledge of methadones pharmacological properties essential to the provider considering methadone as analgesic therapy for a patient with chronic pain. Patient selection
Patients who have sciatic pain (pain in the back, radiating down the buttock to the leg) and clear clinical findings of an identifiable radicular nerve loss caused by a herniated disc will have a better post operative course than those who simply have low back pain. If a specific disc herniation causing pressure on a nerve root cannot be identified, the results of surgery are likely to be disappointing. Patients involved in workers compensation, tort litigation or other compensation systems tend to fare more poorly after surgery.