What is spondylolysis?

Spondylolysis is a spine condition that can be painful. It's a problem with the connection between vertebrae — the bones that make up the spine. Having spondylolysis can lead to small stress fractures or cracks, often after repeated injuries during sports.

Spondylolysis is also known as a "pars defect" because it affects a tiny spinal bone called the pars interarticularis.

Is spondylolysis the same as spondylolisthesis?

Spondylolysis and spondylolisthesis are related but not the same.

  • Spondylolisthesis is when one vertebra slips out of place over the vertebra below.
  • Spondylolysis is a common cause of spondylolisthesis, because the crack in the vertebra may cause the bone to slip.

How common is spondylolysis?

Spondylolysis affects about 3% to 7% of Americans. It’s common in kids and teens, especially those who participate in sports such as gymnastics or football. Overstretching or overextending the spine, but not inflexion (bending inward) can lead to small cracks in the vertebrae.

What causes spondylolysis?

If you have spondylolysis, you typically have a weakness in a section of the vertebra called the pars interarticularis. This thin piece of bone connects the facet joints, which link the vertebrae directly above and below to form a working unit that permits movement of the spine. The cracks are often called pars fractures.

While we don’t know exactly why the weakness occurs, your genes might play a role. You may be born with thin vertebrae, which puts you at higher risk for pars fractures. Repetitive trauma to the lower back — for example, injuring yourself over and over through sports or other activities — can also weaken the pars interarticularis.

What are the symptoms of spondylolysis?

It’s possible to have spondylolysis and not even feel any symptoms. If you do experience symptoms, low back pain is the most common. The pain often:

  • Spreads across the lower back.
  • Feels like a muscle strain.
  • Is made worse with extension

Symptoms often appear during teen growth spurts. The typical age of diagnoses is 15 to 16 years (younger in females).

Last reviewed by a Cleveland Clinic medical professional on 08/07/2020.


  • American Academy of Orthopaedic Surgeons. Spondylolysis and Spondylolisthesis. Accessed 7/30/2020.
  • North American Spine Society. Spondylolysis and Spondylolisthesis. Accessed 7/30/2020.
  • Scoliosis Research Society. Spondylolysis. Accessed 7/30/2020.
  • Tay BB, Freedman BA, Rhee JM, Boden SD, Skinner HB. Chapter 4. Disorders, Diseases, and Injuries of the Spine. In: Skinner HB, McMahon PJ. eds. Current Diagnosis & Treatment in Orthopedics, 5e. New York, NY: McGraw-Hill; 2014. Accessed 7/30/2020.

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy