What Part of the Spine Is Spondylolisthesis?

With spondylolisthesis, one of the spinal bones (vertebra) slips out of its usual position and rests on the bone beneath it. But, what part of the spine is spondylolisthesis primarily located? Considering that an estimated 39 million people are diagnosed with this condition each year, this is a common question among patients today. 

In this article, we’ll explore the areas of the spine affected by spondylolisthesis to help you better understand this condition and the path to improved spinal health. 

Where Is Spondylolisthesis Located?

Spondylolisthesis is most commonly located at the L5-S1 spinal level. 

L5-S1 links the lumbar spine to the sacral spine, which is the area of the spine between the lower back and tailbone. The lumbar and sacral regions of the spine are highly flexible and support the rest of the spine in various positions. This combination of mobility and day-to-day impact makes these parts of the spine particularly susceptible to degenerative conditions, including spondylolisthesis. 

Spondylolisthesis affecting the L5-S1 level is also known as lumbosacral spondylolisthesis. It develops when the L5 vertebra slips over the S1 vertebra and can cause symptoms including:

  • Lower back pain
  • Pain that radiates to the buttocks and/or thighs
  • Weakness, numbness, or tingling in the buttock(s) and/or thigh(s)
  • Tight hamstring muscles
  • Difficulty standing and/or walking for prolonged periods
  • Reduced range of motion in the lower back

Many people with L5-S1 experience relief from lower back pain, numbness, weakness, and tingling when they sit or bend forward. These motions create more space in the spinal canal, which alleviates pressure on the spinal nerves compressed by the displaced vertebra.

Symptoms of Severe L5-S1 Spondylolisthesis

If nerve compression from L5-S1 becomes severe, or if the condition is left untreated, it can cause serious symptoms, including:

  • Severe chronic back pain
  • Loss of bowel or bladder control
  • Loss of sensation in the legs
  • Reduced motor function in the legs
  • Saddle anesthesia

The symptoms listed above indicate cauda equina syndrome, a serious possible complication of L5-S1 spondylolisthesis. The cauda equina is a collection of nerve roots usually positioned at the L1 to L5 spinal levels. It contains nerve roots that supply motor and sensory function to the bladder, legs, anus, and perineum. 

Is Spondylolisthesis Always L5 S1?

Spondylolisthesis isn’t always L5 S1. It can affect any spinal level. 

With that said most cases of spondylolisthesis impact the lower lumbar spine. Besides L5-S1, the L4-L5 spinal levels are very commonly affected by this spinal condition. L4-L5 is often associated with degenerative spondylolisthesis, while L5-S1 is the most prevalent site of isthmic spondylolisthesis.

Degenerative vs. Isthmic Spondylolisthesis

Degenerative and isthmic spondylolisthesis are distinct types of this spinal condition. 

  • Degenerative spondylolisthesis results from age-related spinal changes and gradual wear and tear. It tends to occur in patients over age 50, and its prevalence rises with advanced age. 
  • Isthmic spondylolisthesis results from a fracture or defect of the pars interarticularis (the bone that links the facet joints of the spine). This form of spondylolisthesis is more prevalent in teens and young adults. But, if it’s not recognized at a younger age, it can cause symptoms that worsen in adulthood. 

Why is Spondylolisthesis Common at L4-L5?

L4 and L5 are the two lowest vertebrae of the lumbar spine. They must support all of the vertebrae above when you move, and this physical stress can lead to degeneration over time. Additionally, as mentioned above, the lumbar spine is highly flexible, making this spinal level particularly susceptible to wear and tear. 

What Is Grade 1 Spondylolisthesis L4 5?

Grade 1 spondylolisthesis L4-5 is the most minor form of spondylolisthesis. It’s classified as a 0% to 25% slippage of the affected vertebra by the Meyerding classification system. 

As the least severe type of spondylolisthesis, grade 1 or “low-grade” spondylolisthesis of the L4-L5 levels may not cause any symptoms, at first. But, if the affected vertebra begins to impinge on nearby spinal nerves, it may trigger lower back pain and stiffness. Neurological symptoms like tingling, numbness, and weakness may follow as the condition progresses. 

How Do You Treat Grade 1 Spondylolisthesis of L4 L5?

You can typically treat grade 1 spondylolisthesis of L4 L5 with conservative methods, like activity modifications, physical therapy, and pain medication. 

While conservative methods can’t cure the slippage of the vertebra, they can help alleviate pain and inflammation. Non-surgical methods can also promote nerve healing. However, without surgery, it’s impossible to return the slipped vertebra to its proper position.  

Grade 2 Spondylolisthesis L4 L5

Grade 2 spondylolisthesis is classified as a 25% to 50% slip of the vertebra. This is often still considered low-grade spondylolisthesis, and many people can manage their symptoms without surgery. 

Grade 3 Spondylolisthesis L4 L5

Grade 3 spondylolisthesis involves a 50% to 75% slip of the vertebra. In this stage, the condition becomes more serious and may interfere with your daily activities. Prompt treatment is essential to curb the progression of grade 3 L4 L5 spondylolisthesis

Grade 4 Spondylolisthesis L4 L5

Grade 4 spondylolisthesis is a 75% to 100% slippage. It’s a severe or “high-grade” form of spondylolisthesis that often requires surgery. 

Grade 5 Spondylolisthesis L4 L5

Grade 5 spondylolisthesis occurs when there’s more than a 100% slip of the vertebra. This is also called spondyloptosis, and it’s fairly rare. Usually, grade 5 spondylolisthesis results from significant trauma to the spine and requires prompt surgical treatment to prevent neurological complications. 

Determining Spondylolisthesis Grade and Location

To determine which part of the spine the slippage is located, your physician will likely order imaging tests, such as an MRI or CT scan. These scans allow your physician to view the vertebrae and confirm which spinal level is affected. 

Your physician will use the results of imaging tests and the degree of your symptoms to determine the spondylolisthesis grade. With the Meyerding classification system, the physician draws a line through the posterior wall of the superior and inferior vertebrae to calculate the percentage of the distance between the lines. 

Surgery for Spondylolisthesis of L4-L5

L4-L5 spondylolisthesis often requires surgery when conservative therapies don’t provide symptom improvement. Previously, patients had limited options for procedures to resolve this condition. Spinal fusion was considered the only way to restabilize the spine and correct the slippage caused by spondylolisthesis. 

Spinal fusion is the process of permanently fusing two or more vertebrae for stabilization. It’s often performed after spinal decompression procedures, like laminectomy, which alleviates spinal nerve impingement. However, fusion comes with numerous downsides, including reduced mobility, extensive downtime, and the risk of failed fusion or adjacent segment degeneration. 

Today, patients with lumbar spondylolisthesis have more options at their disposal. One option is the TOPS System, a non-fusion implant that restores a controlled range of motion in the spine. It provides lasting stability while allowing the spine to move in all directions, making it a game-changer for individuals with spondylolisthesis at L4-L5, L2-L3, or L3-L4. 

Regain your mobility with Premia Spine!

David danced at his son’s wedding

Bonnie explains why TOPS surgery was the right decision for her

Wade is back to hiking

Scott speaks about going to surgery

The TOPS System is approved by the FDA for lumbar degenerative spondylolisthesis and spinal stenosis. It’s also earned a superiority-to-fusion claim from the FDA, making it an exciting new option for individuals struggling with persistent spondylolisthesis symptoms. 

Find a physician in your area today to learn more about TOPS for lumbar spondylolisthesis.