title: Spondylolysis and isthmic spondylolisthesis: impact of vertebral hypoplasia on the use of the Meyerding classification.
abstract: BACKGROUND
  Spondylolysis and isthmic spondylolisthesis are common multifactorial disorders. The extent of slipping of the spondylolytic vertebra is considered a major predicator for prognosis and further follow-up. Vertebral hypoplasia is a common finding associated with spondylolysis. The purpose of this study is to evaluate the incidence of hypoplastic vertebral bodies in patients with spondylolysis and in the general population and to analyse the impact of the findings on the measurement and grading of spondylolisthesis.
  
  
  METHODS
  140 patients with 141 levels of spondylolysis identified by MRI were included in this study. The slippage of the spondylolytic vertebral body and the size in the midline sagittal image were measured and correlated. In addition, a randomised control group was evaluated to test the hypothesis that shortened, hypoplastic vertebral bodies can also be found in the general population.
  
  
  RESULTS
  Shortened, hypoplastic vertebrae were found in 50 patients with spondylolysis and none was found in the control group. These shortened vertebrae mimicked spondylolisthesis and in 19 patients the slippage equalled the shortening, thus mimicking spondylolisthesis, although only spondylolysis was present.
  
  
  CONCLUSIONS
  Sagittal shortening of the spondylolytic vertebra is common and may mimic spondylolisthesis. In order to define and measure spondylolisthesis the shortening of the spondylolytic vertebra has to be taken into account.
authors.affiliation: Privatpraxis für Upright MRT, Cologne, Germany. p.niggemann@mrt-koeln.de
authors.forename: P
authors.initials: P
authors.lastname: Niggemann
authors.forename: J
authors.initials: J
authors.lastname: Kuchta
authors.forename: D
authors.initials: D
authors.lastname: Grosskurth
authors.forename: H K
authors.initials: HK
authors.lastname: Beyer
authors.forename: J
authors.initials: J
authors.lastname: Hoeffer
authors.forename: K S
authors.initials: KS
authors.lastname: Delank
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D005260:Female; D006801:Humans; D007511:Ischemia; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011897:Random Allocation; D013131:Spine / Q000473:pathology*; D013168:Spondylolisthesis / Q000145:classification*; D013169:Spondylolysis / Q000473:pathology*