Spondylolysis
Updates to Article Attributes
Spondylolysis is a defect in the pars interarticularis of the neural arch, the portion of the neural arch that connects the superior and inferior articular facets. It is commonly known as pars interarticularis defect or more simply as pars defect.
Epidemiology
Spondylolysis is present in ~5% of the population 2.
Clinical presentation
Spondylolysis is commonly asymptomatic. Symptomatic patients often have pain with extension and/or rotation of the lumbar spine. Approximately 25% of individuals with spondylolysis have symptoms at some time.
It is a common cause of back pain in adolescents, and in particular athletes.
Pathology
Spondylolysis is believed to be caused by repeated microtrauma, resulting in stress fracture of the pars interarticularis. Genetic are also is believed to be a factor. It is more common in men than in women 1.
Location
- ~90% of cases of spondylolysis occur at the L5 level and ~10% occur at L4 level 1, 2
- the process may be unilateral or bilateral
Associations
- ~65% of patients with spondylolysis will progress to spondylolisthesis 2, which is seen radiographically in ~25% 4
- spina bifida occulta
Radiographic features
Plain filmradiograph
- limited sensitivity compared to SPECT and CT 4
- scotty dog sign: on oblique radiographs, a break in the pars interarticularis can have the appearance of a collar around the dog's neck
CT/MRI
- wide-canal sign may be present on sagittal images when there is spondlyolisthesis 3
Treatment and prognosis
Surgery is only considered in rare circumstances as most cases respond to conservative management 2.
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