Conditions · Carrollwood · Tampa Bay
Spondylolisthesis & Slipped Vertebra
What a forward slip on your report actually means, what the grade number is measuring, and how a doctor trained in spinal MRI interpretation connects the picture to the person.
A radiology report is written for other doctors, not for you. So when yours says grade 1 anterolisthesis, pars defect, or spondylolisthesis of L4 on L5, the words land without a translator, and the internet fills the silence badly. This page is the translator. Dr. Bobby Koser, DC, chiropractic physician, completed post-doctoral training in spinal MRI interpretation and clinical correlation, and reviewing the report with the person it belongs to is part of the examination here. Bring yours.
Spondylolisthesis and Slipped Vertebra Overview
What the words on your report mean
Your spine is a stack of vertebrae, the bones of the spinal column, separated by discs, the cushions between those bones, and held in line at the back by paired joints called facet joints. Spondylolisthesis describes one vertebra sitting forward of the one directly below it, so at that one level the stack is offset instead of lined up. The report names the level where it happens, names the direction, and usually attaches a grade. Everything else on this page is about what those three pieces of information do and do not tell you.
Spondylolisthesis
The word is built from two parts: spondylo, meaning vertebra, and listhesis, meaning to slip. Put together it means a vertebra that has shifted forward on the one below it. Reports find it most often in the low back, and the two levels commonly named are the fourth lumbar vertebra sitting forward of the fifth, written L4 on L5, and the fifth lumbar vertebra sitting forward of the sacrum, written L5 on S1. The sacrum is the wedge of fused bone at the base of the spine.
A report can describe the offset with no comment at all about your symptoms, because the radiologist is describing a picture and has not examined you. Connecting the picture to the person is a separate job, and it is what an examination is for.
Also written as: slipped vertebra, spinal slippage, vertebral slippage, olisthesis, olisthetic segment, spondylolisthesis of the lumbar spine.
Anterolisthesis, retrolisthesis, and listhesis
Anterolisthesis is the same forward shift written the anatomical way, since antero means forward. Retrolisthesis is the opposite direction: the vertebra sits behind the one below it rather than in front of it. Listhesis on its own is the shorthand some radiologists use when they are about to name a direction and a level in the next few words.
So a line reading grade 1 anterolisthesis of L5 on S1 is saying that the fifth lumbar vertebra sits forward of the sacrum, by an amount that falls into the first of four measurement brackets. That is the whole sentence. It carries no statement about what you feel.
Also written as: anterior listhesis, retro-listhesis, olisthetic segment, which is the level where the offset sits.
Degenerative spondylolisthesis
This is the type reports name when the bony bridge at the back of the vertebra is intact and the changes the radiologist describes sit at the disc and the facet joints instead. The disc in front and those two joints at the back are what hold one vertebra stacked squarely on the next, and the report names the offset at a level where their shape has changed. Reports commonly name this type at L4 on L5, and it usually appears alongside the other findings written on the same page: loss of disc height, enlarged facet joints, and less open space around the nerves.
That last one has its own name. When the report also says the space around the nerves is narrowed, you are reading about spinal stenosis, and the two findings sit together often. One of the trials in the research section below was run in patients its authors describe as having degenerative spondylolisthesis with spinal stenosis. Disc height loss has its own page too: degenerative disc disease, which is the label a radiologist uses when a disc no longer looks on a scan the way a new disc looks.
Also written as: degenerative anterolisthesis, degenerative listhesis, DS on some reports.
Isthmic spondylolisthesis, and spondylolysis
Behind each vertebra is a narrow strip of bone connecting the joint above to the joint below on each side. It is called the pars interarticularis, and a break in that bony bridge at the back of the vertebra is called spondylolysis. When the bridge is not intact, the front of the vertebra can move forward while the back part of the bone stays where it is, and the report calls the result isthmic spondylolisthesis.
Two words, one letter apart, meaning different things. Spondylolysis is the break in the bone. Isthmic spondylolisthesis is the break plus a forward shift. A report can say spondylolysis and stop there, meaning the bridge is not intact and the vertebra has not moved forward. Reports commonly name this type at L5.
Also written as: pars defect, pars interarticularis defect, bilateral pars defects when it is on both sides, isthmic defect.
The grade, and what it is measuring
The number attached to the word is the Meyerding grade, and it is a measurement of position taken off an image. The radiologist looks at the top surface of the vertebra below, divides that surface into four equal strips front to back, and reports which strip the vertebra above has moved into.
- Grade I: the shift falls within the first quarter, up to 25%.
- Grade II: between one quarter and one half.
- Grade III: between one half and three quarters.
- Grade IV: more than three quarters.
- Grade V: the vertebra has moved off the one below it entirely, which reports call spondyloptosis.
Grades I and II are often grouped as low grade, and grades III and above as high grade. What the grade is not is a score for how much a person hurts, how limited they are, or what will happen to them. It is a distance measured on a picture. The examination is what tests whether that distance explains anything you are feeling, and the two do not automatically move together.
Also written as: grade 1, grade I, or a percentage of slip stated directly, such as 18% anterolisthesis.
Three words that look almost identical
Reports use all three, and one letter is all that separates them on the page.
- Spondylosis: the general word for degenerative change in the spine, the disc and joint wear pattern a report describes at one level or several. Covered on our degenerative disc disease page.
- Spondylolysis: a break in the bony bridge at the back of the vertebra, with or without any forward movement.
- Spondylolisthesis: a vertebra sitting forward of the one below it, which can happen with that break or without it.
If your report has one of these and your paperwork has another, that is worth sorting out before anything else, and it is one of the first things the examination sorts out.
Also written as: spondylotic changes or spondylosis deformans for the wear pattern, lytic spondylolisthesis for the type with a break in the bone, and pars defect for the break itself.
A finding is not a diagnosis
Here is something worth knowing before you read your report again. In one study that used CT scans of adults aged 40 to 80 in an unselected adult community group, spondylolisthesis, a vertebra that has shifted forward on the one below it, was not significantly associated across that group as a whole with whether a person reported low back pain they described as significant in the previous 12 months, and in that same group the degenerative type of the slip grew more common from the fifth through the eighth decade of life.1 That cuts in both directions, and both matter. A finding on your report is not automatically the cause of your pain, and your pain is not less real because the same words appear on other people’s reports. That study analyzed 188 people, so what it tells you is what is common, not what is true for you. In that same study 21 of those 188 people had spondylolysis, the break in the bone, and 38 of the 188 reported significant low back pain, so the groups being compared were smaller still. A result that does not reach statistical significance in a study of 188 people is not a demonstration that the finding never matters for a given person, and it is a poor reason to stop asking about yours.
A second body of evidence points the same way in a younger group. In a meta-analysis that pooled 14 MRI studies of 3,097 adults aged 50 and younger, spondylolisthesis was not found significantly more often in the people who reported low back pain than in the people who did not, while several other findings on the same scans, including disc bulge, disc protrusion and disc extrusion, the report words for a disc pressing outward past its normal footprint, contained by its outer ring or through it, along with disc degeneration, the wear pattern in the disc itself, and spondylolysis, a break in the bony bridge at the back of the vertebra, were found more often in the group with pain.2 In that meta-analysis, the forward slip came out at an odds ratio of 1.59 with a 95% confidence interval running from 0.78 to 3.24, a comparison between two groups and its range of statistical uncertainty rather than a number about any one person, and that range is compatible with anything from somewhat less common in the group with pain to roughly three times the odds in the group with pain. A range that wide does not settle the question in either direction. Everyone pooled in that meta-analysis was 50 or younger, and the degenerative type of the slip grew more common from the fifth through the eighth decade of life in the community study above, so this says very little about the older patients in whom the degenerative type keeps becoming more common. And the break in the bone behaved differently from the slip in the same analysis: spondylolysis was found more often in the people reporting pain. Those are associations measured across those studies, not a cause.
So the report is the starting point and not the finish line. Whether the offset at your level explains your symptoms depends on where it sits, which nerves run past it, what your strength and reflexes and sensation show, and whether all of that matches what you actually feel. Working that out is what an examination is for.
1. Kalichman L, et al. Spondylolysis and spondylolisthesis: prevalence and association with low back pain in the adult community-based population. Spine (Phila Pa 1976). 2009;34(2):199-205. PubMed
2. Brinjikji W, et al. MRI findings of disc degeneration are more prevalent in adults with low back pain than in asymptomatic controls: a systematic review and meta-analysis. AJNR Am J Neuroradiol. 2015;36(12):2394-2399. PubMed
Symptoms, and the warning signs we screen for
People arrive at this page from two very different starting points. Some have a report in hand and no idea whether the word on it is connected to anything they feel. Others have symptoms and are trying to find out whether the word explains them. Both are the same question asked from opposite ends.
What people describe most often is low back pain that sits across the belt line, sometimes into the buttock or the back of the thigh, and that behaves differently depending on position. Standing and walking, especially standing still for a while, and leaning backward are what people say makes it worse. Sitting down, or leaning forward over a cart, is what they say they look for. Some people describe a step or a ledge along the spine that another person can feel with a hand. When the offset narrows the space where a nerve root leaves the spine, symptoms travel: pain, tingling, or numbness running down a leg in a line rather than sitting in a spot, the pattern many people know as sciatica. When the space around the nerves is narrowed more broadly, people describe leg heaviness or aching that builds after a certain walking distance and settles when they sit, which reports call neurogenic claudication and which is covered on our spinal stenosis page.
Hamstring tightness that does not respond to stretching, and a change in how someone stands, are also described. None of these on its own identifies the level or the grade. They are the reasons the examination is built the way it is.
Common, and examined here
- Low back pain with a slip or a pars defect named on a report
- Pain that builds with standing and walking and eases when you sit
- Pain, tingling, or numbness running down a leg
- Back pain that increases when you lean backward
- Leg heaviness after a predictable walking distance
- An imaging report with a grade on it that nobody has explained to you
Emergency, not an appointment
- New loss of bowel or bladder control
- Numbness in the groin or inner thighs
- Rapidly worsening leg weakness
Together these can signal cauda equina syndrome, a surgical emergency. Go to the emergency department now. This is part of what the examination here screens for.
How we approach spondylolisthesis
The examination comes first, and your imaging report is read with you, not at you. That visit is the Pain Source Exam. Dr. Koser’s post-doctoral training in spinal MRI interpretation and clinical correlation exists for this conversation. The question the visit answers: does the offset on the report explain the person in the room?
Working that out means taking the report apart first. Which level. Which type the report describes, the degenerative one or the one with a break in the bony bridge behind the vertebra. Which grade the radiologist recorded, and whether there is an earlier film anywhere in your history that the current one can be compared against, because a single image shows a position and two images taken apart in time show whether that position has changed. Then the examination tests you rather than the picture: what standing, walking, leaning backward, and leaning forward do to your symptoms, how far you get before anything starts, and what your strength, reflexes, and sensation show in each leg. Those findings are what decide whether the nerves are involved, and they are the ones we recheck later to see whether anything has moved.
When conservative care fits, it is built from that examination rather than from the word on the report. That means specific activity guidance, including which positions and loads to work in for now and which to hold off on; a movement and strengthening plan you can actually follow, aimed at the muscle and motion around that segment; flexion-distraction, which stretches the spine slowly with no thrust; dry needling for trigger points (tight, painful knots in a muscle) or myofascial pain (pain from the muscle and its covering tissue) in the muscles guarding the area; and manual care chosen with the level and the grade in front of us, which for some presentations means working above and below the segment, using an instrument or a no-thrust technique, or not using a manual technique at all. Care here addresses the muscle, the motion, and the load through that part of your back. The plan is monitored, and if you are not progressing, the plan changes. Spondylolisthesis sits inside the wider picture covered on our spine care page.
When the examination points somewhere else, we say so, refer you to the right physician or spine surgeon, and send your records with you. That includes strength that is lower at a recheck, a new foot drop, meaning the front of the foot no longer lifts when you walk, numbness that is spreading, or any other neurological finding that is moving in the wrong direction. A high-grade slip, meaning grade III or above on the report. A slip that has moved between one set of images and the next. Walking distance that keeps shrinking through a monitored trial of care. Any change in bowel or bladder control goes to the emergency department rather than into a referral. And some findings call for a medical workup regardless of the slip: fever or night pain unchanged by position, unexplained weight loss with new spine pain, prior spine surgery or hardware with changed symptoms, or known osteoporosis. Surgery decisions belong with surgeons; making sure you are in the right room is part of the job here.
Hurt in a car accident? A slip named on a report after a crash raises a second question alongside the first one: what changed for you. Your history and the examination are what work that out. Florida law gives you 14 days from the crash to begin care and keep your no-fault medical benefits. If that window is open, start at our auto accident page and we will get you examined.
What the research shows
The two types of slip have been studied separately, so this section is split the same way. Read the paragraph that matches the word on your report.
The degenerative type. A review of the published literature on degenerative spondylolisthesis, the type reports name when the bony bridge at the back of the vertebra is intact, reported that nonoperative treatment should be the initial course of action in most cases, with or without nerve symptoms, and listed pain medication, epidural steroid injections, bracing, and flexion-strengthening exercise among the options. That review also reported that patients with nerve symptoms such as intermittent claudication, leg pain or heaviness that comes on with walking, were the group it expected to deteriorate neurologically without surgery,3 which is why walking distance and the leg findings are rechecked here, and why a walking distance that keeps shrinking is one of the findings that brings a spine surgeon into it. That was a narrative review of the PubMed and MEDLINE literature from 1950 to 2007, which means the authors read and summarized the field rather than pooling results into a single number. Two of the options it named, medication for pain and epidural steroid injections, are handled by physicians rather than at this office. What it speaks to is sequence, for this type of slip, and it says nothing about the type with a break in the bone.
The degenerative type with narrowing around the nerves. In a study run at 13 centers in 11 states, adults who had degenerative spondylolisthesis with spinal stenosis, narrowing of the space around the nerves, and who had had symptoms for at least 12 weeks were offered either a randomized comparison, in which chance decides which treatment each person gets, or an observational group, in which each person and their doctor chose. The randomized comparison enrolled 304 people and the observational group 303. In the randomized comparison itself there was no statistically significant difference between surgery and nonsurgical care on the study’s main measures of pain and function, and about 40% of patients in each direction switched to the other treatment during the first year. When the authors instead pooled both groups and compared everyone by the treatment they actually received, a comparison that was no longer randomized, the surgical patients showed greater improvement in pain and function over two years.4 Everyone enrolled was already a candidate for surgery, with the slip confirmed on imaging and at least 12 weeks of symptoms behind them, and the finding that favored surgery comes from that second, no longer randomized comparison, which the authors adjusted for differences between the groups at the start. It covers the degenerative type with narrowing, and nothing in it carries across to the type with a break in the bone.
The type with a break in the bone. Everyone in the next trial had already had low back pain or sciatica for at least a year and had restricted function, so everyone in it was someone a fusion operation was on the table for. In that randomized trial, 111 adults aged 18 to 55 who had isthmic spondylolisthesis of any grade were assigned by chance either to an exercise program or to a fusion operation, which joins vertebrae together at a level. Over the following two years the surgical group improved on both its pain and its disability scores, while in the exercise group, which was 34 of the 111 against 77 in the fusion arm, pain decreased slightly and the disability score did not change.5 That was one exercise program, in one group of adults who had hurt for at least a year and were being considered for fusion, reported in 2000, and the exercise arm was 34 people. It is not a description of the care delivered here, and it does not describe a person whose slip was picked up on a recent report.
What the amount of slip tracked with, years later. One long-term follow-up study in Finland reassessed 148 middle-aged adults with isthmic spondylolisthesis, a vertebra slipped forward through a break in the bony bridge behind it, an average of 17 years after being treated for low back pain, and about three quarters of that group had had spinal surgery. In that study, how far the slip had progressed over those years did not correlate with the pain index or the daily-activities index, and the amount of slip measured at follow-up showed a weak positive correlation with those two indexes among the patients who had not had a fusion, a group that pooled those treated without surgery with those who had had a decompression.6 In the patients who had been fused, those correlations ran in the other direction and did not reach statistical significance. The authors’ own phrase for that link was slightly associated. That was a treated group, three quarters of it surgically, so it describes what happened to those patients under care and not what a slip does when nothing is done.
Three of those are studies of groups of patients who were already being considered for surgery or already treated, and one is a summary of the published literature. None of them is a prediction for you, and finding out where you actually stand is what the examination is for.
3. Kalichman L, Hunter DJ. Diagnosis and conservative management of degenerative lumbar spondylolisthesis. Eur Spine J. 2008;17(3):327-335. PubMed
4. Weinstein JN, et al. Surgical versus nonsurgical treatment for lumbar degenerative spondylolisthesis. N Engl J Med. 2007;356(22):2257-2270. PubMed
5. Möller H, Hedlund R. Surgery versus conservative management in adult isthmic spondylolisthesis: a prospective randomized study: part 1. Spine (Phila Pa 1976). 2000;25(13):1711-1715. PubMed
6. Virta L, Osterman K. Radiographic correlations in adult symptomatic spondylolisthesis: a long-term follow-up study. J Spinal Disord. 1994;7(1):41-48. PubMed
Common questions about spondylolisthesis
What does spondylolisthesis mean on my report?
It means one vertebra, one of the bones of the spinal column, is sitting forward of the one directly below it, so the stack is offset at that level. The report names the level, such as L4 on L5 or L5 on S1, names the direction, and usually attaches a grade. It is a description of a picture. Whether that offset is connected to what you feel is a separate question that an examination answers.
What is the difference between degenerative and isthmic spondylolisthesis?
They are named for what the report shows behind the vertebra. In the degenerative type the bony bridge at the back of the vertebra is intact and the changes the report describes sit at the disc and the facet joints, and reports commonly name it at L4 on L5, often alongside narrowing of the space around the nerves. In the isthmic type there is a break in the pars interarticularis, the narrow bony bridge at the back of the vertebra, and the front of the bone has moved forward while the back part stayed put; reports commonly name it at L5. The distinction matters because the research on each type is separate, and findings from one do not carry across to the other.
What does grade 1 or grade 2 mean on my imaging report?
The grade is the Meyerding grade, and it is a distance measured on an image. The radiologist divides the top surface of the vertebra below into four equal strips and reports which strip the vertebra above has moved into: grade I is within the first quarter, grade II is between one quarter and one half, grade III between one half and three quarters, grade IV beyond three quarters, and grade V means the vertebra has moved off the one below it entirely. Grades I and II are often grouped as low grade. The number measures position, not how much a person hurts and not how limited they are, and the examination is what tests whether those move together in your case.
My report says spondylolisthesis. Is that why my back hurts?
Not automatically, and this is worth taking seriously in both directions. In one study that used CT scans of adults aged 40 to 80 in an unselected adult community group, a forward slip was not significantly associated across that group as a whole with whether a person reported low back pain they described as significant in the previous 12 months, and that study analyzed 188 people in total. A result that does not reach significance in numbers that small is not a demonstration that the finding does not matter for you. A finding on your report is not automatically the cause of your pain, and your pain is not less real because the same words appear on other people’s reports. Whether yours explains your symptoms depends on the level, the nerves that run past it, and whether the examination findings match what you feel.
Will my spondylolisthesis get worse?
No page and no single image can answer that for one person. If there is an earlier film in your history, the two get compared, and if your symptoms or your examination findings change, repeat imaging is a reasonable thing to ask a physician about. In one long-term follow-up study in Finland, 148 middle-aged adults with the isthmic type were reassessed an average of 17 years after being treated for low back pain, about three quarters of them having had spinal surgery, and how far the slip had progressed over those years did not correlate with their pain index or their daily-activities index. In that same study the amount of slip measured at follow-up showed a weak positive correlation with both of those indexes among the patients who had not been fused, so the two halves of that report point in different directions. What is checkable is your own examination over time. Strength that is lower at a recheck, a new foot drop, meaning the front of the foot no longer lifts when you walk, a walking distance that keeps shrinking, or movement of the slip between one set of images and the next are all reasons to bring a spine surgeon or physician into it.
Can a chiropractor put the vertebra back in place?
That is not what care here is aimed at. The position of the vertebra is a structural finding on an image. What an examination-led plan addresses is the muscle, the motion, and the load through that part of your back, along with specific activity guidance and a strengthening plan. The level and the grade on your report are in front of us when the technique is chosen, and for some presentations that means working above and below the segment, using a no-thrust technique such as flexion-distraction, using an instrument, or not using a manual technique at all and referring instead.
When does spondylolisthesis need a surgeon?
The findings that route a person to a spine surgeon or physician are a neurological deficit that is progressing, meaning strength, sensation, or reflexes moving in the wrong direction between visits; a high-grade slip, which means grade III or above; a slip that has moved between one set of images and the next; and walking distance that keeps shrinking through a monitored trial of care. New loss of bowel or bladder control, numbness in the groin or inner thighs, or rapidly worsening leg weakness are different: those can signal cauda equina syndrome and are an emergency department visit now, not a referral and not an appointment.
Do I need an MRI before coming in?
No. The examination decides whether imaging is needed. If you already have an MRI, a CT, X-rays, or the written report on its own, bring all of it, including anything older, because two images taken apart in time answer a question that one image cannot. Reading the report with you is part of the visit.
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This page is general health information and is not medical advice for any individual. The studies summarized describe groups, not any one person’s outcome, and whether any finding on your imaging explains your symptoms can only be determined by examination. Talk to Dr. Bobby Koser, DC, about your own situation, and seek emergency care immediately for the warning signs listed above.
Bring the report. Leave knowing what the grade means.
A complete examination with Dr. Bobby Koser, DC, your imaging report reviewed with you, and your findings explained the same day.