A defect or crack in the posterior portion of one of the vertebral bones. The broken part is called the pars interarticularis and is between the superior and inferior facet joints of the lamina. It is usually due to a developmental defect but may be the result of a trauma. It may cause instability or a slippage (a spondylolisthesis).
A congenital defect in which a small area of bone in the spine does not fuse completely. This causes weakness in the spine and makes it subject to more frequent and more serious injury. People with spondylolysis should probably not engage in heavy lifting or in contact sports.
Slipping forward of one vertebra over another with stress fracture through the pars interarticularis. Due to repetitive flexion and extension in the adolescent spine. Spondylolysis occurs more frequently in children who are athletic than in sedentary individuals. It is reported to occur in 11% of female gymnasts. Spondylolysis also occurs in a dysplastic form due to underlying congenital abnormalities of the lumbar spine such as partial sacralization of a lower lumbar vertebral body or to an elongated isthmus. A defect in the neural arch between the superior and inferior facets of vertebrae without separation at the defect and therefore no displacement of the vertebrae. Fractures and slippage can also be attributed to high impact accidents generally associated with the cervical spine.