Spondylolysis refers to a defect in one of the vertebra in the lower back. Usually it is the last vertebra of the lumbar spine that is prone to this condition.
The area of the vertebra that is affected is called the pedicle. The pedicle is part of the bony ring that protects the spinal nerves, and is the portion that connects the vertebral body to the facet joints. When a spondylolysis is present, the back part of the vertebra and the facet joints simply are not connected except by soft tissue. This causes spondylolisthtesis, or slippage of the discs. These discs compress spinal nerves and can cause great pain.
This disorder is most common in football players and gymnasts. The current thought is that the spondylolysis is probably a stress fracture that never completely healed.
Spondylolisthesis is the term used to describe when one vertebra slips forward on the one below it. This usually occurs because there is a spondylolysis in the vertebra on top..
People with these conditions boast a higher risk than the normal population of developing chronic low back pain.