<unk>  is a defect in the pars interarticularis of a vertebra.  The great majority of cases occur in the lowest of the lumbar vertebrae (L5), but<unk>  may also occur in the other lumbar vertebrae, as well as in the thoracic vertebrae.<unk>  occurs in three to six percent of the population.
Spondylolysis
Spondylosis
Osteoarthritis
Spondyloarthropathy
Ankylosing spondylitis
Spondylodiscitis
Amyloid arthropathy
Spondylopathies