Failed back surgery syndrome

In one minute

Failed back surgery syndrome is the name given to back or leg pain that persists after a spine operation, or appears after it. It is a label, not a diagnosis: behind it there is usually a specific cause, and the work is to find it. It affects somewhere between one in ten and four in ten operated patients, more after fusion than after discectomy. It feels like the original pain unchanged, a new pain, or leg pain that returns after a good interval. The work-up is the operation report, a careful history of what changed and when, an MRI (magnetic resonance imaging) with contrast, X-rays under load, and sometimes test injections. Some causes are surgical, and those operations can be endoscopic. Many are not, and the honest answer then is a pain programme rather than a third scar.

What it is

The Pain Practice review defines it as persistent back or leg pain despite completed spinal surgery. Older reports call it post-laminectomy syndrome, and it is often written on discharge papers as a diagnosis, which it is not. The term says that an operation did not end the pain. It does not say why.

The Pain Medicine review sorts the contributing factors by when they arise: before, during or after the operation. The StatPearls review fills in the list. Before the operation: depression, anxiety or other psychiatric illness, obesity, smoking, a compensation claim, or a poorly chosen candidate or operation. During the operation: the wrong level, one level operated on when the pain came from several, an inadequate decompression, a misplaced screw, or a nerve injured during surgery. After the operation: the causes the Pain Practice review names as the common ones, new stenosis, a recurrent herniation, scar around the root (epidural fibrosis) and a segment that did not fuse (pseudarthrosis), together with wear at the level next to a fusion, a facet or sacroiliac joint that now carries the load, and nerve pain that outlives its cause.

Causes and risk factors

The StatPearls review puts the prevalence at 10% to 40% of patients after back surgery, with 30% to 46% after lumbar fusion and 19% to 25% after microdiscectomy. The range is wide because the definition is loose and because studies count different things: a pain score, a second operation, or a patient's own verdict.

The pre-operative factors with the strongest association in the StatPearls review are psychosocial: depression, anxiety, other psychiatric illness, obesity, smoking, and litigation or a compensation claim. That does not mean the pain is imagined; it means that the same nerve signal is felt and handled differently by a person who is low, sleepless or frightened, and that an operation cannot fix that part.

After fusion, the joints next to the fused segment take more load. A systematic review of sacroiliac joint pain after lumbar or lumbosacral fusion found an average incidence of 37%, with a range of 6% to 75%, rising with the number of fused levels and especially when the sacrum is included.

How it develops

Each cause has its own mechanism, and they can coexist. A recurrent herniation presses the same root again. Scar forms around every operated root; in most people it is silent, and in some it is the source of the pain. An unfused segment moves a little with every step and hurts the way a broken bone that has not knitted hurts. A decompression that took too much of the facet joint can let the segment slip. A nerve compressed for too long before the first operation may stay painful after it is freed, a neuropathic pain that scans cannot show. And long-standing pain changes how the nervous system handles pain signals, which is one reason the same imaging can go with very different suffering in two patients.

Symptoms

In our experience the pattern is the clue. Leg pain that went away and returned after months usually means a new herniation or a narrowed foramen. Leg pain that never went away suggests a fragment left behind, the wrong level or scar. Back pain that is worse on standing and walking and eases sitting suggests stenosis, at the operated level or the next one. Back pain that is worse on getting up, turning in bed and lifting suggests an unfused or unstable segment. Pain low and to one side, over the dimple of the pelvis, suggests the sacroiliac joint. Burning, electric pain with numbness in a strip of skin that is present at rest suggests a damaged nerve rather than a compressed one.

Diagnosis

The history does most of the work: what the pain was like before the operation, what was done, how the pain changed in the first weeks, and when and how it came back. The examination looks for a root that has lost strength, sensation or a reflex, for pain reproduced by particular movements, and for the sacroiliac and hip joints, which are the usual impostors.

MRI with gadolinium contrast is the standard test after spine surgery, because it tells scar, which takes up contrast, from disc, which does not. Where metal implants make MRI unreadable, CT (computed tomography) or CT myelography (CT with contrast dye in the spinal fluid) is used instead, and CT is also the test for whether a fusion has joined. Standing X-rays with bending views show alignment, any movement at a segment that should be still, and the position of screws and cages. Blood tests are added when infection is possible. When the picture is still ambiguous, a diagnostic injection settles it: a medial branch block for the facet joints, a sacroiliac injection, or a root block. A block that removes the pain for the life of the anaesthetic is strong evidence; one that does not is equally useful.

If you send images for an opinion, include the operation report, the MRI from before the first operation, a new MRI (with contrast if it was done), any X-rays or CT, and a sentence comparing the pain now with the pain then.

Treatment without surgery

For most people with this label, treatment is non-surgical, and both reviews recommend an interdisciplinary approach: physiotherapy with a graded exercise programme, for which the StatPearls review cites level II evidence; psychological treatment for the mood and fear that travel with long pain; and medication chosen by the doctor from the anti-inflammatory, antidepressant and anticonvulsant classes. NICE (the UK National Institute for Health and Care Excellence) advises against opioids for chronic sciatica and against gabapentinoids, oral steroids and benzodiazepines for sciatica, because the evidence shows harm without benefit, and asks for a supported plan to come off them where a patient is already taking them.

Injections have a place when a block has identified the source: epidural steroid for an inflamed root, radiofrequency denervation for facet pain after a positive medial branch block, and injection of the sacroiliac joint. StatPearls rates the studies of epidural steroid in this group as moderate or weak in quality. Adhesiolysis, a catheter procedure to break up scar, is described in the reviews for pain driven mainly by scar around the nerve.

Spinal cord stimulation deserves a plain account because patients are often offered it. It is an implanted electrode that delivers pulses to the spinal cord. The interventional pain review reports studies showing it effective and cost-effective in this population, and StatPearls cites large randomised trials showing benefit over conservative management and repeat surgery, while noting that the permanent implant fails to give reliable long-term relief in about 40% of patients. The 2023 Cochrane review took the opposite view: moderate-certainty evidence that stimulation probably does not improve back or leg pain, function or quality of life compared with placebo at six months, and in one study 31% of patients needed revision surgery for the device within two years. Two good sources disagree, and a patient should hear both before consenting.

When surgery is considered

A further operation is considered only when the work-up has found a cause that surgery can correct and that matches the symptoms: a recurrent herniation with matching leg pain, a narrowed canal or foramen with matching claudication or root pain, an unfused or unstable segment with matching mechanical pain, or implants that are broken, loose or in the wrong place. It is also considered, without waiting, when a root is losing strength or when bladder or bowel control is affected.

The StatPearls review notes that each further operation carries a progressively lower chance of relieving the pain, and that reoperation in general goes with inferior outcomes and higher morbidity than a stimulator; the Pain Practice review reserves revision surgery for a clear indication such as progressive neurological loss or a problem with implants. That is the honest reason a surgeon should decline to operate when no such cause has been found.

Surgical options

The operation is the one that fits the cause, and it is chosen after the cause is proven, not before. For a recurrent herniation, revision discectomy, which can be endoscopic: a randomised trial found full-endoscopic revision equal to microsurgical revision with less tissue damage. For a narrowed canal or foramen at the same or the neighbouring level, decompression, endoscopic where the anatomy allows and open where it does not. For an unfused or unstable segment, fusion, endoscopic or open, with a cage and screws. For a problem with implants, their removal or revision. Where a fusion has caused sacroiliac pain, the joint is treated in its own right, with injections first and, rarely, its own fusion. Spinal cord stimulation is a pain-clinic implant rather than a spine operation.

How we treat it at spine.uz

Send the operation report, the old and new MRI, any X-rays or CT and a description of how the pain has changed; a doctor from the team replies by voice within 48 hours, free of charge. For this condition the honest answer is often that there is no surgical cause, and the useful part of an opinion is then what the scans do show and what the next step is, whether that is a contrast MRI, a diagnostic block or a pain programme. Every patient receives a written conclusion from the team.

When there is a surgical cause, the operation is the smallest one that will correct it. Endoscopic revision discectomy or decompression is done through a 7 mm incision, with no screws or implants; most endoscopic decompressions are done without general anaesthesia, under local anaesthesia with sedation, and the anaesthetist and surgeon decide per patient. Most patients walk on the day of surgery and go home within 24 hours. When a segment needs fusion, the team performs it fully endoscopically, with an interbody cage and percutaneous screws. Across 27,600+ endoscopic and spine operations, the team's complication rate is well below 1%.

Recovery and outcomes

Outcomes depend on the cause. When a second operation is done for a recurrent herniation, the 2016 systematic review reports good or excellent results in 70.6% to 89% of open revision discectomies and 81% to 90.2% of minimally invasive ones. For reoperation in general, StatPearls reports inferior outcomes and higher morbidity, and a falling chance of relief with each further operation.

For those managed without surgery, the aim is function rather than a pain score of zero: walking distance, sleep, work. Graded exercise improves function, and NICE asks clinicians to promote return to work and normal activity. Patients with this label carry more pain, unemployment, opioid use and disability than other chronic pain groups, the StatPearls review notes, and comorbid depression was recorded in 20% to 23% of hospitalised patients in a United States national sample, so mood is treated as part of the condition, not as a side issue.

Living with it and prevention

The Pain Medicine review puts prevention first. In practice that means a diagnosis that matches the scan, conservative care first, and, as NICE advises, no fusion for low back pain outside a trial. After any spine operation, keep moving, keep the trunk muscles working, do not smoke, and treat low mood early. Pain that returns after a good interval deserves a proper work-up rather than another prescription, because a cause that is found can often be fixed, and a cause that is not found should not be operated on.