Spondylolysis is a stress fracture. It occurs in a part of the vertebrae (spinal bone). The pars interarticularis is a portion of the bone between the facets. There is a right and left section.

This condition occurs in the lower back. About 90% of the time, it is in the fifth lumbar vertebra. It can fracture on one or both sides (bilateral). Left untreated, it can lead to spondylolisthesis. This is a more serious condition. The vertebra slips forward on the one below it. Both conditions can cause back pain.

This fracture is the most common cause of back pain in adolescent athletes.

Spondylolysis
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Spondylolysis can be caused by:

  • Congenital defect in the spine (usually appears a few years after birth)
  • Acute trauma to the back
  • Degenerative conditions of the spine