Spondylolysis

Spondylolysis is a stress fracture involving the pars interarticularis of one of the vertebral bones of the spine. The pars interarticularis is located on left and right, between the upper and lower azygapophysial or facet joints, and connects the vertebral body in front with the vertebral arch behind (posterior).

This condition occurs in the lower back (at L5 90% of the time) and can be on one or both sides (bilateral). Left untreated, bilateral spondylolysis can lead to spondylolisthesis. This is a more serious condition in which one vertebra slips forward on the one below it. Both conditions can cause back pain by disturbing biomechanics in the back or by pinching a nerve as it leaves the spinal column. About 6% of the general population has spondylolysis. Spondylolysis is the most common cause of back pain in adoloescent athletes.