title: A slip above a slip: retrolisthesis of the motion segment above a spondylolytic spondylolisthesis.
abstract: OBJECTIVE
  The purpose of this study is to assess the degenerative changes in the motion segments above a L5S1 spondylolytic spondylolisthesis and to view these in light of the retrolisthesis in the segment immediately above the slip.                                                 A spondylolytic spondylolisthesis causes an abnormal motion and predisposes to degenerative changes at the L5S1 disc. Degenerative changes in the adjacent segments would influence the symptomatology and natural history of the disease and the treatment options. The extent of degenerative changes in the levels immediately above a L5S1 spondylolytic spondylolisthesis is not well documented in the literature. We have noted retrolisthesis at this level, but this has not been previously reported or assessed.
  
  
  METHODS
  Thirty-eight patients with a symptomatic L5S1 spondylolytic spondylolisthesis with a mean age of 52.8 years (95% CI 47.2-58.4); 55.3% (n = 21) females and 44.7% (n = 17) males. We assessed the lumbar lordosis, slip angle, sacral slope, grade of the slip, facet angles at L34 and L45 on both sides, facet degenerative score (cartilage and sclerosis values), disc degenerative score (Pfirrmann) at L34, L45 and L5S1 and the presence of retrolisthesis at L45.
  
  
  RESULTS
  We noted that 29% (11) had a retrolisthesis at L45. The degenerative scores reduced significantly from L5S1 through L45 and L34. Slip angle and L45 disc degenerative score were the only factors that occurred consistently in patients with a retrolisthesis.
  
  
  CONCLUSIONS
  There is a cascade of degenerative changes that involve both the disc and the facet joints at the levels above a spondylolytic spondylolisthesis. The degenerative changes at the L45 disc and a higher slip angle are consistent findings in patients with a retrolisthesis at the level above the slip.
authors.affiliation: Bristol Orthopaedic Spine Service, North Bristol Trust, Frenchay Hospital, Beckspool Road, Bristol, BS16 1LE, UK. Jwalant_mehta@hotmail.com
authors.forename: Jwalant S
authors.initials: JS
authors.lastname: Mehta
authors.forename: S
authors.initials: S
authors.lastname: Kochhar
authors.forename: I J
authors.initials: IJ
authors.lastname: Harding
mesh_terms: D005260:Female; D006801:Humans; D007403:Intervertebral Disc / Q000473:pathology*; D008161:Lumbosacral Region; D008297:Male; D008875:Middle Aged; D013168:Spondylolisthesis / Q000473:pathology*; D013169:Spondylolysis / Q000473:pathology; D021801:Zygapophyseal Joint / Q000473:pathology*