By the age of 60, 88% of adults with no back pain already show disc degeneration on MRI, and 38% have a small localised disc herniation (the radiological term is protrusion). An abnormal image is therefore not enough to identify the cause of the pain, nor to decide on an operation.
An MRI shows a herniation or another abnormality and you do not know whether surgery is needed? Noria Health Hub can arrange a full check-up or a second medical opinion in Brussels, with a report within 24 h, coordinate your care where needed across more than 40 medical pathways in 48 h, then, if your medical condition allows, arrange surgery within 7 days.
What MRI finds in people who hurt nowhere
A systematic review of 33 studies and 3,110 asymptomatic people gives the prevalence of spinal abnormalities by age band. It is worth reading slowly.
| Abnormality visible on MRI | At 20 | At 40 | At 60 | At 80 |
|---|---|---|---|---|
| Disc degeneration | 37% | 68% | 88% | 96% |
| Disc bulge | 30% | 50% | 69% | 84% |
| Disc protrusion | 29% | 33% | 38% | 43% |
| Annular fissure | 19% | 22% | 25% | 29% |
| Facet degeneration | 4% | 18% | 50% | 83% |
| Spondylolisthesis | 3% | 8% | 23% | 50% |
None of these people had any spinal pain. Source, American Journal of Neuroradiology, 2015.
In other words, at 60, one adult in two with no back pain at all has visible facet degeneration, and nearly 7 in 10 a disc bulge. Finding an abnormality on an image says nothing in itself about the origin of the pain. That is the first reason a second opinion makes sense here, and it is more solid than any published discordance rate.
Surgical practice varies sharply from one region to another
In the United States, lumbar fusion rates vary by close to a factor of 20 between regions, one of the widest variations recorded for any surgical procedure. These differences persist over time, which shows that local practice habits weigh heavily on the decision to operate.
You might think this is about how care is paid for. It is not. In Finland, a single-payer public system, regional rates still vary by a factor of 4 for disc herniation surgery and by a factor of 2 for fusion.
Disc herniation: what can improve without surgery
| What was measured | The result |
|---|---|
| Herniation regression without surgery, 38 studies, 2,219 patients | 63% regression, confidence interval 49 to 77%. But 84% in retrospective studies against 37% in randomised trials, meaning the more rigorous the method, the lower the rate |
| Regression by type of herniation | 96% for a sequestered disc, 70% for extrusion, 41% for protrusion, 13% for a simple bulge. The more impressive the herniation looks on the image, the more likely it is to disappear on its own |
| Symptom course | 60 to 80% of patients improve within 6 to 12 weeks, 80 to 90% beyond a year |
The regression measured is radiological. The disappearance of the image and the disappearance of the pain are not synchronised, in either direction.
Sciatica: when surgery mainly buys faster relief
Two randomised trials give apparently opposite answers that in fact complete each other.
| The trial | What it finds |
|---|---|
| 283 patients with sciatica, early surgery against prolonged conservative care, 2008 | 95% of patients in both arms report satisfactory recovery at 1 year. At 2 years, 81.3% against 78.9%. But 44% of the conservative arm had eventually been operated on. Surgery relieves faster, it does not change the destination |
| 128 patients with sciatica persisting 4 to 12 months, 2020 | Leg pain at 6 months of 2.8 against 5.2 out of 10 in favour of surgery, a significant difference. When pain has already lasted months, operating changes something |
The SPORT trial: why it is hard to interpret
The SPORT trial is a landmark, but it is hard to interpret because patients moved between treatment groups. Of 501 patients randomised for disc herniation, only 57% of the group assigned to surgery had been operated on at 1 year, while 41% of the non-surgical group were operated on in the end. That substantial crossover weakens the trial’s ability to compare the two strategies cleanly over the long term.
The direct consequence. In intention-to-treat analysis, the only one that remains randomised, no endpoint reaches significance at 4 or 8 years. The striking results favouring surgery all come from as-treated analysis, which compares patients who chose surgery with patients who refused it, and reintroduces exactly the bias randomisation was meant to remove.
SPORT shows that surgery speeds up improvement in those who choose it. It does not show that it produces a better final state than abstention.
The situations where surgery must not wait
Two situations change the reasoning entirely, and they must be named without dramatising the rest.
| The situation | What the literature says | The caveat |
|---|---|---|
| Cauda equina syndrome | A meta-analysis of 42 studies and 322 patients finds better sensory, motor, urinary and rectal outcomes when surgery happens within 48 hours, with no difference between under 24 h and 24 to 48 h | The largest available prospective cohort, 621 patients, finds no association between delay and functional outcome. The standard remains urgency, the evidence is more fragile than the rule suggests |
| Motor deficit | Across 390 patients, surgery within 3 days is associated with better recovery, with very large gaps | The 3-day threshold was identified on the data themselves, without independent validation. A recent deficit in a young patient is both operated on faster and recovers better, for reasons unrelated to the surgery |
In both cases the practical attitude does not change, you do not wait. But the strength of the evidence is not what people assume, and saying so is more honest than brandishing a threshold.
After surgery: the risk of a further operation
In a national cohort of 1,856 patients operated on for disc herniation and followed for 10 years, the cumulative reoperation rate is 4% at 1 year, 11% at 5 years and 16% at 10 years. In a US database of 308,979 single-level discectomies, it is 14.4% at 5 years, including 6.1% fusion.
And two randomised trials published in the same issue of the same journal in 2016 reach opposite conclusions on adding fusion to decompression. The first, in 247 patients, finds no benefit. The second, in only 66 patients, finds a modest one whose confidence interval grazes zero. There is no consensus answer to that question, and it is precisely in that zone that the 20-fold variation takes on meaning.
What the studies do not allow anyone to claim
We will not say that a second opinion avoids 6 operations in 10. That figure exists in the literature, but in half the studies reviewed the practitioner giving the second opinion is also the author of the publication measuring its value, and recruitment is never systematic. Above all, no study has ever compared the outcomes of patients who followed the first opinion with those who followed the second. A discordance rate is not proof of benefit.
What justifies a second opinion is something else, and it is more solid. It is that imaging does not determine the indication, that 3 people in 10 with no pain at all already have a protrusion at 20, and that fusion rates vary 20-fold between two regions of the same country.
In practice, if this concerns you
You set out your problem, your symptoms or your question. Reports, test results and images already available can be studied before you arrive, so that the pathway is prepared. The aim is not to run every possible test, but to select those that can genuinely help confirm a hypothesis, rule out a risk or guide the decision. The results are then brought together and the next steps organised. Follow-up is coordinated from there.
Need a medical opinion quickly? For a concern that does not call for emergency services, you can ask to speak to a doctor at any time through Noria Health Hub. This on-demand medical consultation is billed separately from the work-up pathway.
Further reading
The companion articles.
What” rel=”noopener” target=”_blank”>https://noriahealth.com/blog/what-waiting-costs-in-orthopaedics/”>What waiting costs in orthopaedics
Pain” rel=”noopener” target=”_blank”>https://noriahealth.com/blog/pain-that-waits-what-the-literature-measures/”>Pain that waits, what the literature measures
Sources
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Weinstein JN et al., United States trends and regional variations in lumbar spine surgery 1992 to 2003, Spine, 2006. https://doi.org/10.1097/01.brs.0000248132.15231.fe
Mäntymäki H et al., Regional variation in lumbar spine surgery, Archives of Orthopaedic and Trauma Surgery, 2023. https://doi.org/10.1007/s00402-021-04313-0
Wang Y et al., The incidence of regression after the non-surgical treatment of symptomatic lumbar disc herniation, BMC Musculoskeletal Disorders, 2020. https://doi.org/10.1186/s12891-020-03548-z
Chiu CC et al., The probability of spontaneous regression of lumbar herniated disc, a systematic review, Clinical Rehabilitation, 2015. https://doi.org/10.1177/0269215514540919
Kögl N et al., Lumbar disc herniation, the significance of symptom duration for the indication for surgery, Deutsches Ärzteblatt International, 2024. https://doi.org/10.3238/arztebl.m2024.0074
Peul WC et al., Prolonged conservative care versus early surgery in patients with sciatica, two year results of a randomised controlled trial, BMJ, 2008. https://doi.org/10.1136/bmj.39223.428495.BE
Bailey CS et al., Surgery versus conservative care for persistent sciatica lasting 4 to 12 months, New England Journal of Medicine, 2020. https://doi.org/10.1056/NEJMoa1912658
Weinstein JN et al., Surgical versus non-operative treatment for lumbar disc herniation, four-year results for the SPORT, Spine, 2008. https://doi.org/10.1097/BRS.0b013e31818ed8f4
Lurie JD et al., Surgical versus non-operative treatment for lumbar disc herniation, eight-year results for the SPORT, Spine, 2014. https://doi.org/10.1097/BRS.0000000000000088
Weinstein JN et al., Surgical versus nonsurgical therapy for lumbar spinal stenosis, New England Journal of Medicine, 2008. https://doi.org/10.1056/NEJMoa0707136
Ahn UM et al., Cauda equina syndrome secondary to lumbar disc herniation, a meta-analysis of surgical outcomes, Spine, 2000. https://pubmed.ncbi.nlm.nih.gov/10851100/
Presentation, management and outcomes of cauda equina syndrome up to one year after surgery, The Lancet Regional Health Europe, 2023. https://pubmed.ncbi.nlm.nih.gov/36426378/
Thomé C et al., Motor recovery depends on timing of surgery in patients with lumbar disk herniation, Neurosurgery, 2022. https://doi.org/10.1227/NEU.0000000000001825
Kim CH et al., The long-term reoperation rate following surgery for lumbar herniated intervertebral disc disease, Spine, 2019. https://pubmed.ncbi.nlm.nih.gov/30973508/
Long-term reoperation rates after single-level lumbar discectomy, a nationwide cohort study, Spine, 2025. https://doi.org/10.1097/BRS.0000000000005328
Försth P et al., A randomized, controlled trial of fusion surgery for lumbar spinal stenosis, New England Journal of Medicine, 2016. https://doi.org/10.1056/NEJMoa1513721
Ghogawala Z et al., Laminectomy plus fusion versus laminectomy alone for lumbar spondylolisthesis, New England Journal of Medicine, 2016. https://doi.org/10.1056/NEJMoa1508788
Gattas S et al., Second opinion in spine surgery, a scoping review, Surgical Neurology International, 2021. https://doi.org/10.25259/SNI_399_2021
NHS England, Referral to Treatment Waiting Times, April 2026 data. https://www.england.nhs.uk/statistics/statistical-work-areas/rtt-waiting-times/