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 and higher in the adolescent athletic population. It is more common in men than in women 1.
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 low back pain in adolescents and in particular athletes.
Pathology
Spondylolysis is believed to be caused by repeated microtrauma, resulting in a stress fracture of the pars interarticularis. A dysplastic pars is usually present. Genetics are also believed to be a factor.
Traumatic pars defects result from high-energy trauma where there is hyperextension of the lumbar spine and are rare in a congenitally normal vertebra.
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 In most patients this occurs before the age of 16.
- spina bifida occulta
Radiographic features
Imaging features depend on the age of the lesion.
Plain radiograph
- 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
- inverted Napoleon hat sign
CT/MRI
- wide-canal sign may be present on sagittal images when there is spondylolisthesis 3
- deviation of the spinous process
- sclerosis of the contralateral pedicle
Classification
Hollenberg classification 6
This is a classification system mostly based on MRI features
-
Gradegrade 0:(Normalnormal pars interarticularis). MRI; MRI:Nono signal abnormality, pars interarticularis intact -
Gradegrade I: stress reaction). MRI; MRI:Marrow edema. Intactmarrow oedema; intact cortical margins. -
Gradegrade II:(Incompleteincomplete stress fracture). MRI: Marrow edema. Incomplete; MRI: marrow oedema; incomplete cortical fracture or fissure. -
Gradegrade III:(Acuteacute complete stress fracture). MRI: Marrow edema. Complete; MRI: marrow oedema; complete cortical fracture extending through pars interarticularis. -
Gradegrade IV:(Chronicchronic stress fracture). MRI; MRI:Nono marrow edema. Fractures completely extending through pars interarticularis.
Treatment and prognosis
Surgery is only considered in rare circumstances as most cases respond to conservative management 2.
Differential diagnosis
-</ul><h4>Hollenberg classification <sup>6</sup>-</h4><ul>- +</ul><h4>Classification</h4><h5>Hollenberg classification <sup>6</sup>
- +</h5><p>This is a classification system mostly based on MRI features</p><ul>
-<strong>Grade 0</strong> (Normal pars interarticularis). MRI: No signal abnormality, pars interarticularis intact</li>- +<strong>grade 0:</strong> normal pars interarticularis; MRI: no signal abnormality, pars interarticularis intact</li>
-<strong>Grade I </strong>(Stress reaction). MRI: Marrow edema. Intact cortical margins.</li>- +<strong>grade I:</strong> stress reaction; MRI: marrow oedema; intact cortical margins.</li>
-<strong>Grade II</strong> (Incomplete stress fracture). MRI: Marrow edema. Incomplete cortical fracture or fissure. </li>- +<strong>grade II:</strong> incomplete stress fracture; MRI: marrow oedema; incomplete cortical fracture or fissure. </li>
-<strong>Grade III</strong> (Acute complete stress fracture). MRI: Marrow edema. Complete cortical fracture extending through pars interarticularis. </li>- +<strong>grade III: </strong>acute complete stress fracture; MRI: marrow oedema; complete cortical fracture extending through pars interarticularis. </li>
-<strong>Grade IV </strong>(Chronic stress fracture). MRI: No marrow edema. Fractures completely extending through pars interarticularis. </li>- +<strong>grade IV: </strong>chronic stress fracture); MRI: no marrow edema. Fractures completely extending through pars interarticularis. </li>
References changed:
- 6. Hollenberg G, Beattie P, Meyers S, Weinberg E, Adams M. Stress Reactions of the Lumbar Pars Interarticularis. Spine (Phila Pa 1976). 2002;27(2):181-6. <a href="https://doi.org/10.1097/00007632-200201150-00012">doi:10.1097/00007632-200201150-00012</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/11805665">Pubmed</a>
- 6. Hollenberg GM, Beattie PF, Meyers SP, Weinberg EP, Adams MJ. Stress reactions of the lumbar pars interarticularis: the development of a new MRI classification system. Spine (Phila Pa 1976). 2002 Jan 15;27(2):181-6. doi: 10.1097/00007632-200201150-00012. PMID: 11805665.
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