| Discussion: |
Background: Spondylolysis is a common clinical condition that can result in low back pain. Patients with spondylolysis have a defect in the pars interarticularis of the neural arch, that portion of the neural arch that connects the superior and inferior articular facets.
Pathophysiology: Spondylolysis is believed to be caused by repeated microtrauma, resulting in stress fracture of the pars interarticularis. Heredity also is believed to be a factor. Patients with spina bifida occulta have an increased risk for spondylolysis. Approximately 95% of cases of spondylolysis occur at the L5 level. Lyses can occur much less commonly at other lumbar or the thoracic levels. Involvement of multiple levels is rare. The process may be unilateral or bilateral.
Patients with bilateral pars defects can progress to spondylolisthesis. The degree of slippage of adjacent vertebral bodies varies and can progress over time."