Spondylolisthesis: When a Vertebra Slips Forward, What Is Really Going On?
Spondylolisthesis is when one vertebra slides forward over the one below it. It most often affects the lower back. Many people have no symptoms at all. Others get persistent back or leg pain. A standing, weight-bearing scan is the clearest way to see how far the slip goes when your body is upright and carrying load.
Key points
- Spondylolisthesis means a vertebra has slipped forward. It is graded from mild to severe.
- Degenerative wear and tear is the most common cause in adults.
- Pain often appears in the lower back, buttocks or legs, but some people feel nothing.
- Scans done lying down can underestimate the slip because gravity is removed.
- An EOS standing scan shows the slip under real weight-bearing conditions.
The word spondylolisthesis comes from Greek. "Spondylo" means vertebra, and "listhesis" means to slip. Put simply, one of the bones in your spine has moved forward out of its normal place. This usually happens in the lower back, at the base of the spine.
Spondylolisthesis is surprisingly common. Many people find out by chance on an X-ray taken for something else. The key question is not only whether there is a slip. It is how much the slip moves when you stand upright and your spine carries your full body weight.
What are the symptoms of spondylolisthesis?
The most common symptom is a deep, aching pain in the lower back. It gets worse when you stand, walk or arch backwards. Some people also feel pain, tingling or heaviness in one or both legs. Others have no symptoms at all.
A deep ache across the lower back, often worse after standing or walking for a while.
Pain, numbness or a "heavy" feeling that travels into the buttocks or down the legs.
Tight hamstrings and a feeling that your back does not bend as easily as it should.
Some people have a slip but feel nothing. It may only show up on a scan done for another reason.
Important: If you have sudden leg weakness, loss of bladder or bowel control, or numbness around the groin, get urgent medical help. Contact your doctor or go to the emergency department of your nearest hospital. These symptoms need to be checked immediately.
What causes spondylolisthesis in adults?
In adults, the most common cause is degenerative wear and tear. Over the years, the discs and joints that hold each vertebra in place slowly weaken, and this lets one bone shift forward. Other causes include a stress fracture in the vertebra (called a pars defect) or, less often, changes from earlier surgery or other bone conditions.
Age-related wear on the discs and facet joints. The most common type in adults over 50.
A small crack in the back part of the vertebra, often from repeated strain in younger years.
Earlier spinal surgery, bone disease or injury can occasionally lead to instability and slipping.
Whatever the cause, spondylolisthesis is graded from mild to severe, based on how far the vertebra has moved. Even a mild slip can cause real symptoms if it narrows the space around the spinal nerves. On the other hand, a larger slip may cause no pain at all.
Is spondylolisthesis serious?
Most cases of spondylolisthesis are mild and manageable. Many people live with a small slip and have little or no disruption to daily life. A slip becomes more of a concern when it presses on nerves, causes persistent pain or gets worse over time. That is why accurate imaging matters. Knowing the exact position of the slip, and whether it changes when you stand, helps your clinician decide whether you need active management or simple monitoring.
Why does a standing scan show spondylolisthesis more accurately?
Standing, weight-bearing imaging captures the slip in real-life conditions, with gravity pulling on the spine and your muscles working to hold you upright. When you lie down for a usual scan, the muscles relax and the vertebra may settle back towards its normal position. This can make a slip look smaller than it really is, or hide it completely.
An EOS scan takes a full-length, weight-bearing image of your spine and pelvis in one pass while you stand naturally. It shows the true extent of any slip, and how your pelvis, hips and legs are compensating. The radiation dose is about 90% less than a standard X-ray, around ten times less.
Standard X-rays, CT and MRI are usually done lying down. Without the load of gravity, the vertebra can shift back into place. This may underestimate the grade of the slip and miss compensating changes in your posture.
Your body is a connected chain from your feet to your head. When one vertebra slips forward, the rest of the spine, the pelvis and the legs adjust to keep you balanced. A standing, whole-body image captures all of these changes in a single view. Imaging of one area done lying down misses this context.
When is MRI the better choice? EOS shows bones, joints and alignment clearly. For soft tissue, discs or nerves, MRI is usually the better tool. If your clinician suspects the slip is pressing on a nerve, they may recommend MRI alongside EOS imaging or instead of it.
Thinking of coming to London and wondering whether a standing scan would add useful information about your spondylolisthesis? We can talk it through.
Book a free video consultationWhat generally helps manage spondylolisthesis?
Management depends on how severe the slip is and the symptoms it causes. Most people with a mild slip respond well to conservative approaches recommended by their clinician. These usually include physiotherapy to strengthen the core and stabilise the spine, changing activities to avoid movements that make symptoms worse, and pain management guided by your doctor or specialist.
Accurate diagnostic imaging plays a key role in guiding these decisions. A clear, weight-bearing view of the slip, together with measurements of your overall spine and pelvis alignment, gives your treating clinician the detail they need to plan the right approach for you.
Before you start a treatment, or change the one you are on, it is worth getting a detailed diagnosis. Knowing whether the cause sits in the pelvis, the legs or the spine changes what will actually help.
ScanAlign is a diagnostic imaging clinic. We do not provide treatment. We provide the detailed imaging that helps the right clinician make the right plan. You can learn more about what an EOS scan involves and how it works.
Frequently asked questions about spondylolisthesis
Most people describe a deep ache in the lower back that gets worse with standing, walking or arching backwards. Some also feel pain, tingling or heaviness in one or both legs. Others feel nothing at all.
Spondylolisthesis is graded on a scale from 1 to 4, based on how far the vertebra has slipped. Grade 1 is the mildest. It means only a small part of the bone has moved forward. Many people with a grade 1 slip manage well with physiotherapy and monitoring.
It can, especially the degenerative type, as the joints and discs keep wearing. That is one reason repeat imaging from time to time can be valuable: to track whether the slip is stable or getting worse.
Movements that bend the lower back backwards, such as deep backbends, heavy overhead lifting and high-impact activities, are generally best avoided. Your physiotherapist or specialist can give you a list suited to your own slip and symptoms.
Yes. Degenerative spondylolisthesis is caused by age-related wear and tear on the facet joints and discs. It usually affects adults over 50 and most often occurs at the L4-L5 level. The isthmic type comes from a stress fracture in the vertebra itself and tends to develop earlier in life.
When you lie flat, gravity is removed and your muscles relax. The slipped vertebra can settle back closer to its normal position. This makes the slip look smaller than it is in real life, or hides it completely.
Yes. An EOS scan uses about 90% less radiation than a standard X-ray, around ten times less. You can find more detail on the FAQs and safety page.
No. ScanAlign accepts self-referrals. You start with a free video consultation, where a specialist radiographer discusses your situation and confirms whether EOS imaging is right for you.
The price for patients travelling from abroad is confirmed during the free video consultation. You can read more on the FAQs page. The first video consultation is free and there is no obligation to go ahead.
EOS imaging gives your surgeon or specialist a detailed, weight-bearing view of the slip and your overall spinal alignment. This information helps them decide whether conservative management is enough or whether surgery should be considered. ScanAlign does not provide treatment or surgical advice.
See the full picture of your spondylolisthesis
A free video consultation with a specialist radiographer, from wherever you are. No referral needed. No obligation.
Book a free video consultationWritten by Abbas Dhami (Specialist Diagnostic Radiographer)
Sources
- NHS. "Spondylolisthesis." nhs.uk. Accessed 2024.
- Kalichman L, et al. "Spondylolysis and spondylolisthesis: prevalence and association with low back pain in the adult community-based population." Spine, 2009; 34(2): 199-205.
- Illés T, Somoskeöy S. "The EOS imaging system and its uses in daily orthopaedic practice." International Orthopaedics, 2012; 36(7): 1405-1411.
Learn more about spinal conditions and EOS imaging.
This page is general information and not a diagnosis.
ScanAlign is the trading name of CoreMed Solutions Ltd and operates under The Harley Street Hospital's CQC licence.