The spine is made of several bones called vertebra. They are lined up so the spinal cord can run through the center of the bones. Spondylolisthesis is when one of the vertebrae (usually in the lower back area) slips out of place. It moves forward compared to the vertebra below and develops slowly over time.

Spondylolisthesis
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Spondylolisthesis is most often caused by a stress fracture. The fracture can make the vertebra unstable and allow it to slip forward. This type of fracture often occurs when a lot of stress and pressure is put on the back. This can occur with certain sports activities.

The condition can also be caused by spinal problems that are present at birth, like spina bifida.