title: Lumbar facet anatomy changes in spondylolysis: a comparative skeletal study.
abstract: Opinions differ as to the exact mechanism responsible for spondylolysis (SP) and whether individuals with specific morphological characteristics of the lumbar vertebral neural arch are predisposed to SP. The aim of our study was to reveal the association between SP and the architecture of lumbar articular facets and the inter-facet region.
  
  
  METHODS
  Using a Microscribe three-dimensional apparatus (Immersion Co., San Jose, CA, USA), length, width and depth of all articular facets and all inter-facet distances in the lumbar spine (L1-L5) were measured. From the Hamann-Todd Human Osteological Collection (Cleveland Museum of Natural History, OH, USA) 120 normal male skeletons with lumbar spines in the control group and 115 with bilateral SP at L5 were selected. Analysis of variance was employed to examine the differences between spondylolytic and normal spines.
  
  
  RESULTS
  Three profound differences between SP and the norm appeared: (1) in individuals with SP, the size and shape of L4's neural arch had significantly greater inter-facet widths, significantly shorter inter-facet heights and significantly shorter and narrower articular facets; (2) only in the L4 vertebra in individuals with SP was the inferior inter-facet width greater in size than the superior inter-facet width of the vertebra below (L5) (38.7 mm versus 40 mm); (3) in all lumbar vertebrae, the right inferior articular facets in individuals with SP were flatter compared to the control group.
  
  
  CONCLUSIONS
  Individuals with L4 "SP" characteristics are at a greater risk of developing fatigue fractures in the form of spondylolysis at L5.
authors: Spinal Research Laboratory, Physical Therapy, The Stanley Steyer School of Health Professions, Sackler Faculty of Medicine, Tel-Aviv University, P.O. Box 39040, 69978 Tel-Aviv, Israel. yossefm@post.tau.ac.il
authors: Youssef
authors: Y
authors: Masharawi
authors: Gali
authors: G
authors: Dar
authors: Smadar
authors: S
authors: Peleg
authors: Nili
authors: N
authors: Steinberg
authors: Dvora
authors: D
authors: Alperovitch-Najenson
authors: Khalil
authors: K
authors: Salame
authors: Israel
authors: I
authors: Hershkovitz
mesh_terms: D006801:Humans; D008159:Lumbar Vertebrae / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D013169:Spondylolysis / Q000453:epidemiology / Q000473:pathology*; D021801:Zygapophyseal Joint / Q000473:pathology*