Spondylolysis is one of the most common causes of low back pain among adolescents and teenagers. It is caused when a vertebra becomes weakened due to a stress fracture. This condition usually affects the fourth or fifth lumbar vertebrae.
The condition may be hereditary in nature but often results from overuse in youth sports (especially weight lifting, gymnastics, cheerleading or football). In some cases, symptoms are not present. Pain similar to that of a muscle strain or spasm that spreads across the low back may persist, though.