page_title: Spondylolysis
section_title: Pathophysiology
hierarchical_section_title: Spondylolysis / Pathophysiology
caption_attribution_description: English: Spondylolysis lumbar pain
context_page_description: Spondylolysis is defined as a defect or stress fracture in the pars interarticularis of the vertebral arch. The vast majority of cases occur in the lower lumbar vertebrae, but spondylolysis may also occur in the cervical vertebrae.
context_section_description: Spondylolysis is a bony defect or fracture within the pars interarticularis of the vertebral arch in the spinal column. The vast majority of spondylolysis occur in the lumbar vertebrae, however it can also be seen in cervical vertebrae. The lumbar vertebra consist of a body, pedicle, lamina, pars interarticularis, transverse process, spinous process and superior and inferior articular facets, which form joints that link the vertebrae together. When examining the vertebra, the pars interarticularis is the bony segment between the superior and inferior articular facet joints located anterior to the lamina and posterior to the pedicle. Separation of the pars interarticularis occurs when spondylolysis is present in the spinal column.
  Spondylolysis is typically caused by a stress fracture of the bone, and is especially common in adolescents who over-train in activities. The pars interarticularis is vulnerable to fracture during spinal hyperextension, especially when combined with rotation, or when experiencing a force during a landing. This stress fracture most commonly occurs where the concave lumbar spine transitions to the convex sacrum (L5-S1). A significant number of individuals with spondylolysis will develop spondylolisthesis, which is true for 50-81% of this population.
caption: Pars interarticularis marked with red lines
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