title: Morphologic analysis of the facet joint in the immature lumbosacral spine with special reference to spondylolysis.
abstract: METHODS
  Morphological analysis was performed of the facet joint of the normal and spondylolytic lumbosacral spine in children and adolescents.
  
  
  OBJECTIVE
  This study was performed to estimate the influence of spondylolysis on growth of the neural arch of the lumbosacral spine.
  
  
  BACKGROUND
  The development of the facet joint and its relation to spondylolysis have not been documented in the literature.
  
  
  METHODS
  The dimension and orientation of the facet joint at L5/S were measured on radiographs and computed tomography scans from 144 boys without pars defects and 104 boys with pars defects. The latter group was further investigated according to the stage of pars defects. Patients in both groups were between 9 and 18 years of age.
  
  
  RESULTS
  Growth of the facet joint in the sagittal and transverse directions and the increase of the transverse angle were remarkable up to approximately 13 years of age. Concavity of the facet joints also progressed in children of the same age. The growth of the facet joint in patients with spondylolysis was significantly retarded as the pars defects advanced from the progressive to the terminal stage. The joint surface was more coronal in orientation and flatter in shape compared with controls.
  
  
  CONCLUSIONS
  The present results suggest that pars defects occurring in children disturb or retard the growth of the facet joint and that the morphological characteristics of the joint surfaces in patients with spondylolysis are the consequence of these defects.
authors.affiliation: Department of Orthopedic Surgery, School of Medicine, University of Tokushima, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Miyake
authors.forename: T
authors.initials: T
authors.lastname: Ikata
authors.forename: S
authors.initials: S
authors.lastname: Katoh
authors.forename: T
authors.initials: T
authors.lastname: Morita
mesh_terms: D000293:Adolescent; D000367:Age Factors; D002648:Child; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology*; D012447:Sacrum / Q000000981:diagnostic imaging / Q000473:pathology*; D013169:Spondylolysis / Q000000981:diagnostic imaging / Q000473:pathology*; D014057:Tomography, X-Ray Computed