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Retrolisthesis Explained: When a Vertebra Slips Backward on MRI

Written by Ifije Ohiorhenuan, MD, PhD — Board-Certified Spine Neurosurgeon. Last updated 2026-07-03.

Retrolisthesis means that one vertebra has shifted slightly backward compared with the vertebra below it. It may show up on an MRI (magnetic resonance imaging) or on an X-ray of the spine.

The word can sound alarming — many people read it and worry their spine is “slipping out of place.” Usually it is a descriptive imaging finding, not a diagnosis. Its importance depends on the amount of slip, whether nerves are crowded, whether the level is unstable, and whether your symptoms match that level.

What Retrolisthesis Means

The root “listhesis” means slippage — one bone has shifted position relative to another. Two direction words describe which way:

  • Anterolisthesis: the upper vertebra slips forward.
  • Retrolisthesis: the upper vertebra slips backward.

By itself, retrolisthesis does not tell us whether the finding is painful, dangerous, or surgical.

MRI reports may describe it a few ways — “mild retrolisthesis,” “Grade 1 retrolisthesis,” “2 mm retrolisthesis,” or naming the level, such as “retrolisthesis at L4-L5” or “L5-S1.” Some reports give an exact measurement in millimeters; others just say mild, moderate, or severe.

In my practice, I explain retrolisthesis as an alignment finding first — not a diagnosis that automatically explains pain.

Why It Happens

Retrolisthesis can occur in the neck, mid-back, or low back, though most reports describe it in the lumbar spine (lower back). It usually appears with age-related wear. That does not mean it should be ignored — it means the word needs context.

Degenerative disc changes

A spinal disc is the cushion between two vertebrae, and degenerative disc disease is wear-and-tear change in that disc over time. As a disc loses height, the bones above and below can settle differently, and one vertebra may sit slightly backward relative to the one below. This is often described alongside disc height loss or a disc bulge (disc material extending beyond its usual border).

Learn more: Degenerative Disc Disease, Lumbar

Facet joint arthritis

Facet joints are small joints in the back of the spine that guide and stabilize motion. Facet arthropathy means arthritis or wear in these joints; facet hypertrophy means they have become enlarged, often from that arthritis. Retrolisthesis can appear alongside facet arthritis as part of the same degenerative process.

Learn more: Facet Arthropathy and Facet Joint Hypertrophy

Prior injury or altered mechanics

Less often, retrolisthesis relates to prior injury, prior surgery, spinal deformity, or unusual spine mechanics — how the spine moves and carries load. A level that carries more stress may show more wear over time.

Is Retrolisthesis Serious?

Sometimes, but not always. The word sounds serious because a vertebra has shifted, but many cases are mild, and a small backward slip may cause no symptoms at all.

It matters more when it is linked with:

  • Nerve compression: pressure on a nerve.
  • Spinal canal narrowing: less room in the main tunnel where nerves travel.
  • Foraminal narrowing: narrowing of the side opening where a nerve exits the spine.
  • Instability: abnormal motion between two vertebrae.
  • Progressive neurologic symptoms: worsening nerve-related problems, such as weakness or numbness.
  • Severe mechanical back pain: pain that seems to come from movement or loading of the spine.

I do not treat the word “retrolisthesis” in isolation — I treat the patient’s symptoms, exam, and whole imaging picture. The finding matters most when it is paired with nerve compression, instability, or symptoms that match the level.

Does Retrolisthesis Mean the Spine Is Unstable?

Usually not — this is one of the most common worries, so let me be clear: most retrolisthesis seen on MRI is stable. The vertebra has settled into a slightly shifted position, often as part of disc degeneration and normal aging, and it stays there.

Instability has a specific meaning: abnormal movement between two vertebrae — the level moving more than it should when you bend. That is different from a slip that simply sits in one position on a still image. A standard MRI is a single snapshot taken lying down; it shows where the bones rest, not how they behave when you move, so the word “retrolisthesis” alone does not tell you whether a level is unstable.

When instability is a genuine concern — with a larger slip, significant movement-related back pain, or worsening symptoms — doctors check with flexion-extension X-rays, standing views taken bending forward and backward that show whether the vertebra moves more than expected. A small, fixed retrolisthesis that does not change between those views is generally considered stable. Instability is the exception, judged by how the spine moves, not by the label on a single image.

Can Retrolisthesis Cause Pain?

It can be related to pain, but it is not always the cause. MRI findings and pain do not match perfectly: some people have major-looking findings with little pain, while others have significant pain with milder findings.

Retrolisthesis and back pain

Retrolisthesis can be associated with back pain, especially when it is part of a degenerative motion segment — two vertebrae, the disc between them, and the joints around them. If the disc is worn, the facet joints are arthritic, and the level moves poorly, that area may contribute to back pain. But MRI alone cannot prove retrolisthesis is the exact pain generator (the structure actually causing pain).

Retrolisthesis and leg pain or sciatica

Sciatica is pain that travels down the leg from irritation of a spinal nerve; radiculopathy means symptoms from an irritated or compressed nerve root (the part of a nerve as it leaves the spine). Retrolisthesis itself does not “pinch a nerve” simply by existing. It may contribute to nerve crowding if it occurs with other findings, such as:

  • Disc bulge
  • Facet hypertrophy
  • Ligament thickening
  • Foraminal stenosis
  • Lateral recess stenosis
  • Central canal stenosis

Stenosis means narrowing. The lateral recess is a small side channel inside the spinal canal where a nerve travels before it exits; the central canal is the main tunnel that holds the nerves.

Learn more:

What L4-L5 Retrolisthesis Means

L4-L5 is the level between the fourth and fifth lumbar vertebrae in your lower back. It is a common motion segment that carries heavy mechanical load and moves constantly during bending, lifting, sitting, and standing.

L4-L5 retrolisthesis may be seen with degenerative disc disease, facet arthropathy, spinal stenosis, disc bulge, or disc herniation (disc material pushed out farther than a simple bulge).

The useful question with a report that says “L4-L5 retrolisthesis” is whether the level is crowding the nerves and whether your symptoms fit that level. When I see it, I look at the L4-L5 disc, the facet joints, and the spaces where the L5 nerve roots travel. That does not mean L4-L5 retrolisthesis automatically affects the L5 nerve root — it depends on the pattern of narrowing and symptoms.

How Reports Describe Retrolisthesis

Reports use different language, and retrolisthesis is only one part of the picture.

Mild retrolisthesis

Usually a small backward shift. Sometimes the report gives a number, such as 2 mm or 3 mm; other times it just says “mild.” Mild does not automatically mean unstable — nor harmless. It has to be read with the rest of the MRI.

Grade 1 retrolisthesis

Some reports use grading similar to spondylolisthesis grading, where Grade 1 is a smaller amount of slip. The system can vary by report and clinician, and the surrounding findings often matter more than the grade alone.

Learn more: Listhesis Grading I Through V, Meyerding Classification

Retrolisthesis with stenosis

Retrolisthesis matters more when it contributes to stenosis — narrowing of the central canal, the lateral recess, or the foramen where a nerve exits. Alignment and nerve compression are not the same thing: retrolisthesis describes alignment, stenosis describes crowding around nerves.

Learn more:

Retrolisthesis vs. Spondylolisthesis

Retrolisthesis is technically a type of listhesis — backward slippage. Many people hear “spondylolisthesis” and picture only a forward slip, but in common use it means one vertebra slipping relative to another, and that slip can be forward, backward, or sideways.

The key terms:

  • Anterolisthesis: forward slip.
  • Retrolisthesis: backward slip.
  • Spondylolisthesis: vertebral slippage.
  • Spondylolysis: a stress fracture or defect in a part of the vertebra called the pars.
  • Spondylosis: age-related arthritis or wear in the spine.

The pars is a small bridge of bone in the back of the vertebra.

Learn more:

What Doctors Look For Beyond the Word

On MRI I look past the alignment line at whether the slipped level is also narrowing the spaces where the nerves travel. The key questions:

  • How much slip is present — mild, moderate, or severe?
  • Is the disc degenerated or reduced in height?
  • Are the facet joints arthritic or enlarged?
  • Is there central canal, foraminal, or lateral recess stenosis?
  • Is a nerve root compressed?
  • Do the symptoms match that level, and are there neurologic deficits?

A neurologic deficit means a measurable nerve problem, such as weakness, loss of reflexes, or loss of feeling. The core judgment is whether the alignment change is actually crowding the nerves or simply sitting there as part of the aging pattern.

How Retrolisthesis Is Usually Treated

Treatment depends on the whole picture — your symptoms and physical exam, whether there is nerve compression, instability, or neurologic deficits, how much the symptoms affect daily life, and what has already been tried.

When there are no emergency findings, many people with mild degenerative retrolisthesis start with non-surgical care. Common categories include:

  • Activity changes
  • Physical therapy
  • Anti-inflammatory medication, if appropriate
  • Injections in selected cases
  • Evaluation by a spine specialist when symptoms persist or neurologic signs are present

The goal is not to “treat the retrolisthesis” as a word on a report; it is to treat the pain pattern, nerve compression, or instability if those are truly present. Surgery is generally considered based on nerve compression, instability, deformity, severe persistent symptoms, or neurologic deficit — not the MRI word alone. In my practice, the decision comes from the combination of symptoms, exam findings, imaging, and the patient’s goals.

When Retrolisthesis Needs Prompt Medical Attention

Most retrolisthesis findings are not spine emergencies. But certain symptoms should not wait.

Seek urgent medical care now if you have new loss of bladder or bowel control, numbness in the saddle area, rapidly worsening leg weakness, trouble walking from weakness, fever with severe back pain, unexplained weight loss with a history of cancer, or severe pain after a major fall or injury.

The saddle area means the groin, genitals, buttocks, and inner thighs.

These symptoms can be signs of serious problems, including cauda equina syndrome. Cauda equina syndrome is a rare spine emergency where nerves at the bottom of the spinal canal are compressed.

Learn more: Cauda Equina Syndrome: The Spine Emergency Patients Need to Recognize

If the retrolisthesis is in the neck and you have worsening hand clumsiness, balance problems, frequent falls, or weakness in the arms or legs, you should be evaluated promptly because these can be signs of spinal cord involvement.

The spinal cord is the main nerve cable that runs from the brain through the neck and upper back.

Learn more: Cervical Spinal Stenosis & Cervical Myelopathy

How to Make Sense of Your MRI Report

MRI reports often list several findings at the same level — retrolisthesis, disc bulge, facet arthropathy, foraminal narrowing, central canal stenosis, lateral recess stenosis, or Modic changes (MRI signal changes in the bone next to a worn disc, seen with disc degeneration). The hard part is knowing which of these matter and which are just background aging.

A good interpretation connects three things:

  1. The words in the report
  2. The images themselves
  3. The symptom pattern and exam findings

Learn more: How to Read Your Spine MRI Report

Frequently Asked Questions

Can retrolisthesis be reversed?

Non-surgical treatment focuses on symptoms, strength, mechanics, and nerve irritation rather than “moving the bone back.” Surgery is reserved for selected cases — usually nerve compression, instability, deformity, neurologic deficit, or severe symptoms that have not improved with appropriate non-surgical care.

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References

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