Disc herniation

What it is

How a guideline and a review define it

A 2011 BMJ Clinical Evidence chapter describes a herniated lumbar (lower back) disc as displaced disc material¹. The material comes from the nucleus pulposus or the annulus fibrosus, and it lies beyond the intervertebral disc space¹. Each intervertebral disc has an inner nucleus pulposus, an outer annulus fibrosus and cartilage endplates⁶. The endplates anchor the disc to the vertebrae (spinal bones) above and below⁶.

A 2012 North American Spine Society guideline defines lumbar disc herniation with radiculopathy (a nerve root problem that brings numbness, weakness or weaker reflexes)⁷. In its definition, disc material is displaced in one place beyond the normal margins of the disc space⁷. The result is numbness, weakness or pain that follows a myotomal or dermatomal pattern⁷. A myotome is the group of muscles one nerve root serves, and a dermatome is the matching area of skin.

A review describes a herniated or prolapsed disc as one that bulges or ruptures backward, or backward and to one side⁸. It presses on nerve roots inside the spinal canal, the channel in the spine that holds the spinal cord⁸. Herniation of the L4/L5 or L5/S1 disc, the two lowest lumbar discs, can cause sciatica^9,10. Sciatica is pain felt along the path of the sciatic nerve, in the buttock and down the leg.

Four names for what a scan shows

A 2020 study of lumbar disc herniation took its definitions from the North American Spine Society task-force nomenclature³:

• Bulge: soft tissue reaches beyond the ring apophyses around the whole circumference of the disc³. Ring apophyses are the growth rims around the top and bottom edges of a vertebral body.
• Protrusion: a herniation whose displaced material is narrower than its base³.
• Extrusion: a herniation in which any part of the material beyond the disc space is wider than its base³.
• Sequestration: a herniation whose displaced material has lost continuity with the disc space³.

A herniation on a scan is not always felt

The BMJ Clinical Evidence chapter states that a disc herniation shows on imaging in 19% to 27% of people who have no symptoms¹. It adds that herniation on imaging does not reliably predict future low back pain or correlate with symptoms¹.

A 1994 MRI study looked at 98 people without back pain and found a disc bulge in 52%². A protrusion was found in 27% and an extrusion in 1%². Its authors concluded that a bulge or protrusion on MRI may often be a coincidence when found in someone with low back pain². A systematic review of imaging in 3,110 people without back pain found disc bulges in 30% at age 20 and 84% at age 80¹¹.

A 1994 MRI study looked at 98 people without back pain and found a disc bulge in 52%.

Who it affects

How common it is

• Prevalence (the share of people with a condition at a given time). The BMJ Clinical Evidence chapter puts symptomatic herniated lumbar disc at roughly 1% to 3% in Italy and Finland, depending on age and sex¹.
• Incidence (new cases in a group over a set time). A systematic review of 87 studies looked at lumbar disc herniation with nerve-root symptoms¹⁰. It gave the limits of 95% confidence intervals (ranges that show how precise a result is) around yearly estimates¹⁰. Those limits ran from 0.3 to 2.7 per 1,000 people when cases were defined by surgery¹⁰. When cases were defined by clinical signs, they spread far more widely, between 0.1 and 298.3 per 1,000¹⁰.
• Age and sex. The BMJ Clinical Evidence chapter reports that herniated lumbar disc is most prevalent at ages 30 to 50 and gives two males for each female¹.
• Level. In its background, the systematic review puts 95% of symptomatic herniated discs in people aged 25 to 55 at L4/L5 and L5/S1¹⁰.
• The neck. In a records survey of 561 people with cervical (neck) radiculopathy in Rochester, Minnesota, a confirmed disc protrusion was responsible in 21.9%¹².

What goes with it

The systematic review of 87 studies found several factors associated with developing lumbar disc herniation with nerve-root symptoms¹⁰:

• middle age, 30 to 50 years¹⁰;
• smoking¹⁰;
• higher body mass index, a measure of weight for height¹⁰;
• cardiovascular (heart and blood vessel) risk factors in women¹⁰;
• greater cumulative lumbar load at work from forward-bent postures and manual handling¹⁰.

Lifting and sport

The BMJ Clinical Evidence chapter lists weight-bearing sports, such as weight lifting and hammer throw, among the risk factors for disc herniation¹.

A 1993 case-control study covered 287 people with lumbar and 63 with cervical disc herniation¹³. A case-control study compares people who have a condition with similar people who do not. Most of the sports it examined showed no association with a higher herniation risk, and may be protective¹³. Using weight lifting equipment showed no association with herniation at either level¹³. The study noted a possible association between free weights and cervical herniation, with a confidence interval that ran from lower to higher risk¹³.

Another 1993 case-control report, on lifting outside work, covered 287 people with signs and symptoms of a herniated lumbar disc¹⁴. Frequent lifting outside work of loads of 25 pounds or more, with straight knees and a bent back, was linked to a higher risk¹⁴.

What studies found

How it goes without surgery

The 2012 North American Spine Society guideline could not establish the natural history of lumbar disc herniation that comes with radiculopathy⁷. None of the studies its work group identified reported results for control patients who received no care beyond pain medication⁷. In the absence of reliable evidence, the work group gave its opinion that most such people will improve whatever care they receive⁷.

The BMJ Clinical Evidence chapter states that clinical improvement is usual in most people¹. By its account, only about 10% still have enough pain after 6 weeks to consider surgery¹.

One study followed 199 people whose leg pain had resolved during usual non-surgical care for a symptomatic lumbar disc herniation¹⁵. The cumulative risk of leg pain recurring was 23% at 1 year and 51% at 3 years¹⁵. The authors note that these estimates depend on the definitions used¹⁵.

How the herniation changes on scans

In a 2024 meta-analysis of 2,233 people who had non-surgical care for lumbar disc herniation, pooled incidence of disc resorption was 70.39%⁴. It and two systematic reviews counted how often each type regressed (shrank) or was resorbed without surgery^4,16,17:

In a 2024 meta-analysis of 2,233 people who had non-surgical care for lumbar disc herniation, pooled incidence of disc resorption was 70.39%.

Type	2015 review, nine studies	2023 review, 360 cases	2024 meta-analysis, 2,233 people
Bulge	13%16	13.3%17	13.33%4
Protrusion	41%16	52.5%17	37.53%4
Extrusion	70%16	70.4%17	66.91%4
Sequestration	96%16	93.0%17	87.77%4

The 2024 meta-analysis concluded that resorption mainly occurred within 6 months⁴.

The US trial of surgery, and its follow-ups

The US Spine Patient Outcomes Research Trial randomised 501 surgical candidates, assigning them to groups by chance⁵. Each had a lumbar disc herniation on imaging and at least 6 weeks of radiculopathy⁵. Its reports found^5,18:

• At 2 years. The group assigned open discectomy (surgery that removes disc material) and the group assigned non-surgical care both improved substantially⁵. Differences favoured surgery, but for the primary outcomes they were small and not statistically significant⁵.
• Changing groups. Half of those assigned to surgery had it within 3 months, and 30% of those assigned to non-surgical care had surgery in that time⁵. The authors said this meant the as-randomised analysis did not warrant conclusions about which approach was better⁵.
• Those who declined randomisation. Of 743 such candidates, 528 had surgery and 191 had usual non-surgical care¹⁹. Both groups improved, and those who chose surgery reported greater improvement¹⁹. The authors caution that such non-randomised comparisons of self-reported outcomes are subject to confounding, where another factor could explain a link¹⁹.
• At 4 years. One analysis combined the randomised group with those who declined randomisation, and grouped people by the care they actually received^18,19. It found greater improvement in bodily pain, physical function and disability after open discectomy than after usual non-surgical care¹⁸.

Other trials and pooled results

A single-centre randomised trial studied 128 people whose sciatica from a lumbar disc herniation had lasted 4 to 12 months²⁰. Leg pain at 6 months averaged 2.8 out of 10 in the surgery group and 5.2 with standardised non-surgical care²⁰. Scores at the start were 7.7 and 8.0²⁰.

A 2023 meta-analysis pooled randomised trials in people with sciatica from a lumbar disc herniation²¹. It found very low to low certainty evidence that discectomy reduced leg pain more than non-surgical care²¹. The gap was about 12 points out of 100 up to three months and a negligible 2.3 points at 12 months²¹. Effects on disability were small, negligible or absent, and the risk of any adverse event was similar in the two groups²¹.

Exercise and sport

The 2012 guideline looked at structured exercise programmes used on their own for lumbar disc herniation with radiculopathy⁷. It found there was not enough evidence to recommend for or against them⁷.

A 2021 systematic review and meta-analysis covered 20 studies of elite athletes with a symptomatic lumbar disc herniation²². Of 799 who had surgery, 83.0% returned to play, as did 81.5% of 308 who had non-surgical care²². The difference was not statistically significant²².

A separate systematic review of 14 studies of athletes who had lumbar discectomy found a pooled return-to-sport rate of 81%²³. Only 59% returned at the same level²³. It concluded that rates of return to sport cannot be determined accurately, because the studies were varied and of low quality²³.

Connections

The intervertebral disc page covers the tissue, and the spine page the joints around it⁶. In laboratory tests, a healthy disc herniates only under forces larger than those normally met⁸.

The sciatica page covers the leg pain a herniation can cause⁹. A 2007 BMJ review states that in many people with the clinical symptoms of sciatica, scans show no lumbar disc herniation²⁴. The sciatic nerve arises from the spinal nerves numbered L4 to S3²⁵.

Sources

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Every source the library cites

Changes

• October 9, 2026 First published.