Spondylolisthesis occurs when a vertebra is weakened or stressed so much that it actually begins to slip or shift out of place. If the bone slips too much, it may begin to press on nerves near the spinal column. In this case, surgery may be required to correct the condition. A patient may complain of back stiffness, muscle spasms or tight hamstring muscles. A narrowing of the spinal canal may also occur.

A physician can identify either of these conditions on an X-ray image. An MRI or CT scan can help determine if the bone is pressing on nerves.

If a patient does not respond to conservative treatment, such as rest from physical activity or sports, bracing may be prescribed. Physical therapy will help the patient safely strengthen the back muscles, and periodic X-rays can help determine if slippage of the vertebra is occurring. Patients with spondylolysis typically do not need surgery unless the condition worsens, but if the bone continues to shift out of place, as in spondylolisthesis, or if nerves are damaged, spinal fusion surgery may be necessary.