were similar in patients initially treated surgically or nonsurgically. however, leg pain relief and greater back-related functional status continued to favor those initially receiving surgical treatment. a large study of spinal stenosis from finland found the prognostic factors for ability to work after surgery were ability to work before surgery, age under 50 years, and no prior back surgery. the very long-term outcome (mean follow-up time of 12.4 years) was excellent-to-good in 68% of patients (59% women and 73% men). furthermore, in the longitudinal follow-up, the result improved between 1985 and 1991. no special complications were manifested during this very long-term follow-up time. the patients with total or subtotal block in preoperative myelography achieved the best result. furthermore, patients with block stenosis improved their result significantly in the longitudinal follow-up. the postoperative stenosis seen in computed tomography (ct) scans was observed in 65% of 90 patients, and it was severe in 23 patients (25%). however, this successful or unsuccessful surgical decompression did not correlate with patients' subjective disability, walking capacity or severity of pain. previous back surgery had a strong worsening effect on surgical results. this effect was very clear in patients with total block in the preoperative myelography. the surgical result of a patient with previous back surgery was similar to that of a patient without previous back surgery when the time interval between the last two operations was more than 18 months. post-operative mri findings of stenosis are probably of limited value compared to symptoms experienced by patients. patients' perception of improvement had a much stronger correlation with long-term surgical outcome than structural findings seen on postoperation magnetic resonance imaging. degenerative findings had a greater effect on patients' walking capacity than stenotic findings. postoperative radiologic stenosis was very common in patients operated on for lumbar spinal stenosis, but this did not correlate with clinical outcome. the clinician must be cautious when reconciling clinical symptoms and signs with postoperative computed tomography findings in patients operated on for lumbar spinal stenosis. a study from georgetown university reported on one-hundred patients who had undergone decompressive surgery for lumbar stenosis between 1980 and 1985. four patients with postfusion stenosis were included. a 5-year follow-up period was achieved in 88 patients. the mean age was 67 years, and 80% were over 60 years of age. there was a high incidence of coexisting medical diseases, but the principal disability was lumbar stenosis with neurological involvement. initially there was a high incidence of success, but recurrence of neurological involvement and persistence of low-back pain led to an increasing number of failures. by 5 years this number had reached 27% of the available population pool, suggesting that the failure rate could reach 50% within the projected life expectancies of most patients. of the 26 failures, 16 were secondary to renewed neurological involvement, which occurred at new levels of stenosis in eight and recurrence of stenosis at operative levels in eight. reoperation was successful in 12 of these 16 patients, but two required a third operation. the incidence of spondylolisthesis at 5 years was higher in the surgical failures (12 of 26 patients) than in the surgical successes (16 of 64). spondylolisthetic stenosis tended to recur within a few years following decompression. because of age and associated illnesses, fusion may be difficult to achieve in this group. post operative infection a small minority of lumbar surgical patients will develop a post operative infection. in most cases, this is a bad complication and does not bode well for eventual improvement or future employability. reports from the surgical literature indicate an infection rate anywhere from 0% to almost 12%. the incidence of infection tends to increase as the complexity of the procedure and operating time increase. usage of metal implants (instrumentation) tends to increase the risk of infection. factors associated with an increased infection include diabetes mellitus, obesity, malnutrition, smoking, previous infection, rheumatoid arthritis, and immunodeficiency. previous wound infection should be considered as a contraindication to any further spinal surgery, since the likelihood of improving such patients with more surgery is small. antimicrobial prophylaxis (giving antibiotics during or after surgery before an infection begins) reduces the rate of surgical site infection in lumbar spine surgery, but a great deal of variation exists regarding its use. in a japanese study, utilizing the centers for disease control recommendations for antibiotic prophylaxis, an overall rate of 0.7% infection was noted, with a single dose antibiotic group having 0.4% infection rate and multiple dosage antibiotic infection rate of 0.8%. the authors had previously used prophylactic antibiotics for 5 to 7 postoperative days. based on the centers for disease control and prevention guideline, their antibiotic prophylaxis was changed to the day of surgery only. it was concluded there was no statistical difference in the rate of infection between the two different antibiotic protocols. based on the cdc guideline, a single dose of prophylactic antibiotic was proven to be efficacious for the prevention of infection in lumbar spine surgeries. epidural post-operative fibrosis epidural scarring following a laminectomy for disc excision is a common feature when re-operating for recurrent sciatica or radiculopathy. when the scarring is associated with a disc herniation and/or recurrent spinal stenosis, it is relatively common, occurring in more than 60% of cases. for a time, it was theorized that placing a fat graft over the dural could prevent post operative scarring. however, initial enthusiasm has waned in recent years. in an extensive laminectomy involving 2 or more vertebra, post operative scarring is the norm. it is most often seen around the l5 and s1 nerve roots. adhesive arachnoiditis main article: arachnoiditis myelogram showing typical findings of arachnoiditis in the lumbar spine. fibrous scarring can also be a complication within the subarachnoid space. it is notoriously difficult to detect and evaluate. prior to the development of magnetic resonance imaging, the only way to ascertain the presence of arachnoiditis was by opening the dura. in the days of ct scanning and pantopaque and later, metrizamide myelography, the presence of arachnoiditis could be speculated based on radiographic findings. often, myelography prior to the introduction of metrizamide was the cause of arachnoiditis. it can also be caused by the long term pressure brought about with either a severe disc herniation or spinal stenosis. the presence of both epidural scarring and arachnoiditis in the same patient are probably quite common. arachnoiditis is a broad term denoting inflammation of the meninges and subarachnoid space. a variety of causes exist, including infectious, inflammatory, and neoplastic processes. infectious causes include bacterial, viral, fungal, and parasitic agents. noninfectious inflammatory processes include surgery, intrathecal hemorrhage, and the administration of intrathecal (inside the dural canal) agents such as myelographic contrast media, anesthetics (e.g. chloroprocaine), and steroids (e.g. depo-medrol, kenalog). lately iatrogenic arachnoiditis has been attributed to misplaced epidural steroid injection therapy when accidentally administered intrathecally. the preservatives and suspension agents found in all steroid injectates, which aren't indicated for epidural administration by the u.s. food & drug administration due to reports of severe adverse events including arachnoiditis, paralysis and death, have now been directly linked to the onset of the disease following the initial stage of chemical meningitis. neoplasia includes the hematogenous spread of systemic tumors, such as breast and lung carcinoma, melanoma, and non-hodgkin lymphoma. neoplasia also includes direct seeding of the cerebrospinal fluid (csf) from primary central nervous system (cns) tumors such as glioblastoma multiforme, medulloblastoma, ependymoma, and choroid plexus carcinoma. strictly speaking, the most common cause of arachnoiditis in failed back syndrome is not infectious or from cancer. it is due to non-specific scarring secondary to the surgery or the underlying pathology. nerve injury laceration of a nerve root, or damage from cautery or traction can lead to chronic pain, however this can be difficult to determine. chronic compression of the nerve root by a persistent agent such as disc, bone (osteophyte) or scarring can also permanently damage the nerve root. epidural scarring caused by the initial pathology or occurring after the surgery can also contribute to nerve damage. in one study of failed back patients, the presence of pathology was noted to be at the same site as the level of surgery performed in 57% of cases. the remaining cases developed pathology at a different level, or on the opposite side, but at the same level as the surgery was performed. in theory, all failed back patients have some sort of nerve injury or damage which leads to a persistence of symptoms after a reasonable healing time. management failed back syndrome (fbs) is a well-recognized complication of surgery of the lumbar spine. 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 methadone's 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 worker's compensation, tort litigation or other compensation systems tend to fare more poorly after surgery. surgery for spinal stenosis usually has a good outcome, if the surgery is done in an extensive manner, and done within the first year or so of the appearance of symptoms. oaklander and north define the failed back syndrome as a chronic pain patient after one or more surgical procedure to the spine. they delineated these characteristics of the relation between the patient and the surgeon: the patient makes increasing demands on the surgeon for pain relief. the surgeon may feel a strong responsibility to provide a remedy when the surgery has not achieved the desired goals. the patient grows increasingly angry at the failure and may become litigious. there is an escalation of narcotic pain medication which can be habituating or addictive. in the face of expensive conservative treatments which are likely to fail, the surgeon is persuaded to attempt further surgery, even though this is likely to fail as well. the probability of returning to gainful employment decreases with increasing length of disability. the financial incentives to remain disabled may be perceived as outweighing the incentive to recover. in the absence of a financial source for disability or worker's compensation, other psychological features may limit the ability of the patient to recover from surgery. some patients are simply unfortunate, and fall into the category of "chronic pain" despite their desire to recover and the best efforts of the physicians involved in their care. even less invasive forms of surgery are not uniformly successful; approximately 30,000–40,000 laminectomy patients obtain either no relief of symptomatology or a recurrence of symptoms. another less invasive form of spinal surgery, percutaneous disc surgery, has reported revision rates as high as 65%. it is no surprise, therefore, that fbss is a significant medical concern which merits further research and attention by the medical and surgical communities. total disc replacement lumbar total disc replacement was originally designed to be an alternative to lumbar arthrodesis (fusion). the procedure was met with great excitement and heightened expectations both in the united states and europe. in late 2004, the first lumbar total disc replacement received approval from the u.s. food and drug administration (fda). more experience existed in europe. since then, the initial excitement has given way to skepticism and concern. various failure rates and strategies for revision of total disc replacement have been reported.