Spondylolisthesis with an intact vertebral arch and associated advanced arthritic changes in the facet joints at the level of vertebral displacement is termed degenerative spondylisthesis (DS). The displacement most commonly occurs at the L4/L5 level and rarely exceeds 30% of the width of the adjacent vertebral body. Degenerative spondylisthesis has been the subject of numerous studies since first described by Junghanns in 1930. Many authors have postulated on various risk factors associated with the pathogenesis of DS, yet controversies regarding those risk factors and the etiology of DS still exist.
The primary types of interest to us are the isthmic and degenerative with pars interarticularis defect.Some use etiology and classify spondylolisthesis as acquired or developmental.
, Kimmerly anomaly, posticus ponticusCalcific bridge between the lateral mass and posterior tubercleIn 15% of the populationProper testing for VBAI is recommended (George's test, etc.)Approximately 10% of the patients with arcuate foramen demonstrate signs and symptoms
Significance –minimal clinical significance or risk –question of vertebral artery occlusion
Agenesis of posterior tubercleNo spinolaminar line on posterior tubercleStress hypertrophyFailure in segmentation
Agenesis of posterior arch of C1
Posterior Arch Maldevelopment at L5Associated with spina bifida oculta
Underdevelopment Neck of Scotty dog extremely thinNo contact sports because could cause fracture
Spondylolitic Spondylolisthesis AnterolisthesisLook at Myerding's scale and Ullman's lineSlippage of the L5 body anterior on sacral baseMost reliable way to make sure this does not change overtime is to use the percentage methodSurgical stabilization could be an option (more than 3mm of translation)Etiology is trauma, congenital, stress fracture (obesity, constant loading), pathology (metastasis), or elongated pars (fracture that healed longer)Stress fracture is the most common etiologyDegenerative is the second most common etiologyAverage age of onset of a stress fracture is 18 months old*3 mm or more of translation in considered unstable*