title: The pathogenesis of slippage and deformity in the pediatric lumbar spine: a radiographic and histologic study using a new rat in vivo model.
abstract: METHODS
  Rat lumbar spines with posterior destabilizing surgery were evaluated radiographically and histologically.
  
  
  OBJECTIVE
  To create an appropriate rat model showing the vertebral slippage and deformities frequently observed in pediatric patients with spondylolysis, and to clarify their pathogenesis.
  
  
  BACKGROUND
  There are controversial hypotheses regarding the pathogenesis of slippage and deformities of the pediatric spine with pars defects. Furthermore, there is no appropriate animal model mimicking those conditions.
  
  
  METHODS
  After posterior destabilizing surgery, the lumbar spines of young (4-week-old) and adult (26-week-old) rats were radiographically examined at weekly intervals during 3 weeks, and histologically 3 weeks after the surgery.
  
  
  RESULTS
  Slippage occurred in the young rats, but not in the adult rats. In the young rats, 7.2% slippage was observed 1 week after the surgery, whereas the slippage in the adult rats was 0%. The difference in percentage of slippage between the two groups was significant (P < 0.05). Lumbar deformity also was seen in the young rats, but not in the adult rats. The lumbar index of L6, as an indicator of L6 rounding, was 91.7% immediately after surgery. It had decreased to 87.7, 84.6, and 74%, respectively, 1, 2, and 3 weeks after surgery. Histologic examination showed growth plate injury in the young group and pronounced disc degeneration in the adult group.
  
  
  CONCLUSIONS
  The young rat with posterior destabilizing surgery was an appropriate animal model, mimicking the slippage and deformities radiographically seen in pediatric patients with spondylolysis. The histologic examination indicated that vertebral growth plate impairment was the basic lesion causing such slippage and deformities in pediatric spines.
authors.affiliation: Department of Orthopedics, School of Medicine, The University of Tokushima, Tokushima, Japan.
authors.forename: Tadanori
authors.initials: T
authors.lastname: Sakamaki
authors.forename: Koichi
authors.initials: K
authors.lastname: Sairyo
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Katoh
authors.forename: Hideko
authors.initials: H
authors.lastname: Endo
authors.forename: Shinji
authors.initials: S
authors.lastname: Komatsubara
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Sano
authors.forename: Natsuo
authors.initials: N
authors.lastname: Yasui
mesh_terms: D000375:Aging; D000818:Animals; D002648:Child; D004195:Disease Models, Animal; D018450:Disease Progression; D005260:Female; D006801:Humans; D007796:Laminectomy; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D008161:Lumbosacral Region; D011859:Radiography; D051381:Rats; D017208:Rats, Wistar; D013121:Spinal Curvatures / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000503:physiopathology; D013131:Spine / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000503:physiopathology; D013169:Spondylolysis / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D021801:Zygapophyseal Joint / Q000601:surgery