Spondylolisthesis occurs when one vertebra slips forward onto the vertebrae below it. This produces both a gradual deformity of the lower spine and also a narrowing of the vertebral canal. It is often associated with pain.

Slipped Vertebrae


Spondylolisthesis is officially categorized into five major types:

  • Dysplastic: Caused by a congenital defect (present from birth) in the formation of part of the vertebra called the facet
  • Isthmic: Caused by a defect in a part of the vertebra called the pars interarticularis
  • Degenerative: Occurs when the joints, through arthritis, lose their ability to keep the alignment of the spine in its normal position
  • Traumatic: Caused by trauma or injury to the vertebrae.  A fracture of the pedicle, lamina or facets can cause the vertebra to slip forward
  • Pathologic: Caused by structural weakness of the bone, usually caused by a disease, such as a tumor or other bone disease


The most common symptom of spondylolisthesis is lower back pain. Sometimes, a person can develop the lesion (spondylolysis) at a younger age and not have any symptoms until they are 35 years old, when a sudden twisting or lifting motion will cause an acute episode of back and leg pain. 

The degree of vertebral slippage does not directly correlate with the amount of pain a person will experience. Some people with spondylolisthesis will associate an injury with the onset of their symptoms. 

In addition to back pain, someone with a spondylolisthesis may complain of leg pain. In this situation, there can be associated narrowing of the area where the nerves leave the spinal canal that irritates a nerve root.


Many people with spondylolisthesis will have vague symptoms and very little visible deformity. Often, the first physical sign of spondylolisthesis is tightness of the hamstring muscles in the legs.  

Plain x-rays of the lumbar spine are initially best for diagnosing spondylolysis or spondylolisthesis. Spondylolisthesis is most easily seen on the lateral and oblique views of the spine, but in some cases, specialized imaging studies such as a bone scan or CT scan (CAT scan) are needed to make the diagnosis. People with a dysplastic pars have an elongated interarticular region along with altered pedicles. This is usually best seen by a CT scan.   

Spondylolisthesis is graded according to the amount that one vertebral body has slipped forward on another:

  • Grade I: Less than 25 percent slip
  • Grade II: Between 25 and 50 percent slip 
  • Grade III: Between 50 and 75 percent slip 
  • Grade IV: More than 75 percent slip  
  • Grade V: This means that the upper vertebral body has slid all the way forward off the front of the lower vertebral body. This is a special situation that is called a spondyloptosis and is very rare.


The diagnosis of spondylolysis is confirmed by the discovery of a pars defect on a lateral x-ray or CT scan, and spondylolisthesis is confirmed by noting the forward position of one vertebral body on another.

Flexion and extension views of the lumbar spine may help to identify the presence of instability of the spine (abnormal excessive motion between vertebrae upon movement). This movement may be an important part of the pain experienced and essential to the planning for further treatment.


The non-surgical treatments for spondylolysis and spondylolisthesis are most commonly rest, followed by trunk and abdominal strengthening exercises. A physical therapist is often helpful in getting you back on your feet and can instruct you in the proper way to do these exercises without making your symptoms worse. If you have significant leg pain, you can also take an anti-inflammatory medication. Braces are rarely needed but may be helpful in reducing your symptoms. Anti-inflammatory cortisone injections may also be of help.

For people with spondylolysis, surgery to repair the defect in the pars interarticularis is needed only after non-surgical measures such as physical therapy and exercises have failed to relieve symptoms. In younger people without a slip, surgery may be used to directly repair the pars defect; in older people or in those with some degree of instability, a spinal fusion may be required. If there is slippage, the two main goals are unpinching the nerves and internally stabilizing the spine. Putting things back to normal alignment is often possible as well.

Information on this site should not be used as a substitute for talking with your doctor. Always talk with your doctor about diagnosis and treatment information.