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Retrolisthesis Explained: When a Vertebra Slips Backward on MRI

Written by Ifije Ohiorhenuan, MD, PhD — Board-Certified Spine Surgeon. Last updated 2026-05-12.

Retrolisthesis means that one vertebra has shifted slightly backward compared with the vertebra below it.

A vertebra is one of the bones that makes up your spine. Retrolisthesis may show up on an MRI, which stands for magnetic resonance imaging, or on an X-ray, which is a picture of bone alignment.

The word can sound alarming. Many people read it and worry their spine is “slipping out of place.” In many cases, retrolisthesis is a descriptive imaging finding. It is not a diagnosis by itself. 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 Does Retrolisthesis Mean?

Retrolisthesis means a backward slip of one vertebra compared with the vertebra below it.

The word “listhesis” means slippage or translation. Translation means one bone has shifted compared with another bone.

There are two common direction words:

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

Retrolisthesis is a direction word. It tells us that one spinal bone sits slightly farther backward than expected. By itself, it does not tell us whether the finding is painful, dangerous, or surgical.

MRI reports may describe retrolisthesis in a few ways:

  • “Mild retrolisthesis”
  • “Grade 1 retrolisthesis”
  • “2 mm retrolisthesis”
  • “Retrolisthesis at L4-L5” or “L5-S1”

Millimeters are small units of measurement. Some reports give an exact number. Others use words like mild, moderate, or severe.

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

Why Does Retrolisthesis Happen?

Retrolisthesis can happen in the neck, mid-back, or low back. Many MRI reports discuss it in the lumbar spine, which is the lower back.

It often appears with age-related wear in the spine. 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. Degenerative disc disease means wear-and-tear change in the disc over time.

As a disc loses height, the bones above and below it can sit differently. That change can affect alignment. One vertebra may settle slightly backward compared with the one below it.

This may be described along with disc degeneration, disc height loss, or a disc bulge. A disc bulge means the disc extends beyond its usual border.

Learn more: Degenerative Disc Disease, Lumbar

Facet joint arthritis

Facet joints are small joints in the back part of the spine. They help guide and stabilize motion.

Facet arthropathy means arthritis or wear in these joints. Facet hypertrophy means the facet joints have become enlarged, often from arthritis.

Retrolisthesis may appear along with facet joint arthritis. These findings can be part of the same degenerative process.

Learn more: Facet Arthropathy and Facet Joint Hypertrophy

Prior injury or altered mechanics

Less often, retrolisthesis can be related to prior injury, prior surgery, spinal deformity, or unusual spine mechanics.

Mechanics means 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 it means a vertebra has shifted. But many cases are mild. A small backward slip may not cause symptoms at all.

Retrolisthesis 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.

In my practice, I do not treat the word “retrolisthesis” in isolation. I treat the patient’s symptoms, exam findings, and the whole imaging picture.

The finding matters most when it is paired with nerve compression, instability, or symptoms that match the level.

Can Retrolisthesis Cause Pain?

It can be related to pain in some cases. But it is not always the cause.

MRI findings and pain do not match perfectly. Some people have major-looking MRI findings with little pain. Others have significant pain with more mild findings.

Retrolisthesis and back pain

Retrolisthesis can be associated with back pain, especially when it is part of a degenerative motion segment.

A motion segment means 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 that retrolisthesis is the exact pain generator. A pain generator is the structure actually causing pain.

Retrolisthesis and leg pain or sciatica

Sciatica means pain that travels down the leg from irritation of a spinal nerve. Radiculopathy means symptoms from an irritated or compressed nerve root. A nerve root is 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 in the spine that holds the nerves.

Learn more:

What Does L4-L5 Retrolisthesis Mean?

L4-L5 means the level between the fourth and fifth lumbar vertebrae in your lower back.

This is a common motion segment. It carries a lot of mechanical load. It also moves often during bending, lifting, sitting, and standing.

L4-L5 retrolisthesis may be seen with:

  • Degenerative disc disease
  • Facet arthropathy
  • Spinal stenosis
  • Disc bulge
  • Disc herniation

A disc herniation means disc material has pushed out farther than a simple bulge.

If your report says “L4-L5 retrolisthesis,” the next question is not simply, “Is the bone slipped?” The better question is, “Is this level crowding the nerves, and do my symptoms fit that level?”

When I see L4-L5 retrolisthesis, I immediately 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 the symptom pattern.

How Retrolisthesis Is Described on MRI Reports

MRI reports use different language. The word “retrolisthesis” is only one part of the report.

Mild retrolisthesis

Mild retrolisthesis usually means a small backward shift.

Sometimes the report gives a number, such as 2 mm or 3 mm. Other times it only says “mild.”

Mild does not automatically mean unstable. It also does not automatically mean harmless. It needs to be read with the rest of the MRI.

Grade 1 retrolisthesis

Some reports use grading language similar to spondylolisthesis grading.

Grade 1 generally means a smaller amount of slip. The grading system can vary by report and by clinician.

The surrounding findings often matter more than the grade alone.

Learn more: Listhesis Grading I Through V, Meyerding Classification

Retrolisthesis with stenosis

Retrolisthesis may matter more if it contributes to stenosis.

Stenosis means narrowing around the nerves. This can occur in different places:

  • Central canal stenosis: narrowing of the main spinal canal.
  • Lateral recess stenosis: narrowing of the side channel where a nerve travels.
  • Foraminal stenosis: narrowing of the nerve exit opening.

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. It means backward slippage.

Many people hear “spondylolisthesis” and think only of forward slip. In common use, spondylolisthesis often refers to one vertebra slipping compared with another. That slip can be forward, backward, or sideways.

Here are 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:

  • Spondylolisthesis: When the Bones Slip
  • Spondylosis vs. Spondylolisthesis vs. Spondylolysis: The Three “Spondy” Words

What Doctors Look For Beyond the Word “Retrolisthesis”

What I look for on MRI is not just the alignment line. I look at whether the slipped level is also narrowing the spaces where the nerves travel.

The key questions are:

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

A neurologic deficit means a measurable nerve problem, such as weakness, loss of reflexes, or loss of feeling.

MRI shows anatomy at rest. It is a still picture. It does not always show how much a level moves when you bend forward or backward.

If instability is a concern, flexion-extension X-rays may be used in selected cases. Flexion means bending forward. Extension means bending backward. These X-rays can show whether one vertebra moves more than expected.

What I look for on MRI 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.

That includes:

  • Your symptoms
  • Your physical exam
  • Whether there is nerve compression
  • Whether there is instability
  • Whether there are neurologic deficits
  • How much the symptoms affect daily life
  • What treatments have already been tried

Many people with mild degenerative retrolisthesis start with non-surgical care when there are no emergency findings.

Common treatment categories may 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 usually to “treat the retrolisthesis” as a word on a report. The goal 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. It is not based on the MRI word alone.

In my practice, I do not recommend treatment based on a single MRI word. The treatment 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.

You may see words like:

  • Retrolisthesis
  • Disc bulge
  • Facet arthropathy
  • Foraminal narrowing
  • Central canal stenosis
  • Lateral recess stenosis
  • Modic changes

Modic changes are MRI signal changes in the bone next to a worn disc. They can be seen with disc degeneration.

The hard part is knowing which findings matter and which are just part of the background aging pattern.

A good MRI 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

What is retrolisthesis in simple terms?

Retrolisthesis means one vertebra sits slightly backward compared with the bone below it.

It is an alignment finding. By itself, it does not prove that the spine is unstable or that the finding is causing pain.

Is retrolisthesis serious?

Sometimes, but not always.

It depends on the amount of slip, nerve compression, instability, symptoms, and exam findings. A small slip may be part of a degenerative pattern and may not be the main problem.

Is L4-L5 retrolisthesis dangerous?

L4-L5 is a common level for degenerative changes in the lower back.

L4-L5 retrolisthesis is not automatically dangerous. What matters is whether it is causing stenosis, nerve compression, or instability that matches your symptoms.

Can retrolisthesis cause sciatica?

It can contribute to sciatica if it narrows the spaces around nerves.

But retrolisthesis alone does not always cause sciatica. Leg pain usually depends on whether a nerve root is irritated or compressed.

Can retrolisthesis be reversed?

Non-surgical treatment usually focuses on symptoms, strength, mechanics, and nerve irritation rather than “moving the bone back.”

Surgery is reserved for selected cases. The reason for surgery is usually nerve compression, instability, deformity, neurologic deficit, or severe symptoms that have not improved with appropriate non-surgical care.

What is the difference between retrolisthesis and spondylolisthesis?

Retrolisthesis is backward slip.

Anterolisthesis is forward slip.

Spondylolisthesis is often used broadly for vertebral slippage. In everyday spine care, many people use it to describe a vertebra slipping compared with the one below it.

Does retrolisthesis require surgery?

Usually not by itself.

Surgery depends on the whole clinical picture. This includes nerve compression, instability, deformity, neurologic deficits, symptom severity, and response to non-surgical care.

How do doctors know if retrolisthesis is unstable?

MRI shows a still image of the spine at rest.

Flexion-extension X-rays may be used in some cases. These are bending X-rays that can show whether the vertebra moves abnormally.

Image / Diagram Suggestion

A helpful diagram for this article would show a side view of the lumbar spine.

The image should include:

  • Two stacked vertebrae in normal alignment
  • A second view showing the upper vertebra shifted slightly backward
  • Labels for:
  • Upper vertebra shifted backward
  • Disc space
  • Nerve opening/foramen
  • Spinal canal
  • A small inset showing:
  • Anterolisthesis = forward slip
  • Retrolisthesis = backward slip

Suggested caption: Retrolisthesis means one vertebra sits slightly backward compared with the vertebra below it. The clinical importance depends on whether this shift narrows the canal or nerve openings and whether symptoms match that level.

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References

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