title: Vertebral rounding deformity in pediatric spondylolisthesis occurs due to deficient of endochondral ossification of the growth plate: radiological, histological and immunohistochemical analysis of a rat spondylolisthesis model.
abstract: METHODS
  A study using rat spondylolisthesis models.
  
  
  OBJECTIVE
  To clarify pathomechanism of vertebral rounding deformity in pediatric spondylolisthesis.
  
  
  BACKGROUND
  For high-grade slippage, rounding of sacrum surface associated with L5 spondylolisthesis is reported to be the most responsible risk factor. However, the exact pathomechanism of the rounding deformity is yet to be clarified.
  
  
  METHODS
  Spondylolisthesis rat model (4-week-old) was used. Radiographs were taken weekly for 5 weeks after the surgery. The lumbar spines were harvested for histology. Hematoxylin and eosin, alcian blue staining, and tartrate-resistant acid phosphatase staining were used. Immunohistochemically, the growth plate cartilage was studied for type II and X collagen. A modified bone histomorphometric analysis was also performed.
  
  
  RESULTS
  Radiographs showed slippage 1 week after surgery. Rounding deformity was obvious 2 weeks after surgery. The rounding deformity progressed with time. Three weeks after surgery, the specific columns of growth plate were unclear at the anterior corner, which corresponded to the rounding surface observed on radiographs. Instead, a huge mass of cartilage was observed at that site. Tartrate-resistant acid phosphatase-positive cells were observed in the vicinity of the growth plate except in relation with the anterior corner. The growth plate and cartilage mass at the anterior corner stained positive for type II collagen. Chondrocytes in the hypertrophied layer stained positively for type X collagen; however, staining was faint at the anterior corner. The results suggested that the chondrocytes at the anterior did not form, morphologically and functionally, the normal growth plate. From histomorphometrical analysis, the normal posterior growth plate made endochondral bone growth in 510 +/- 20 microm for a week, whereas the anterior corner in 200 +/- 15 microm.
  
  
  CONCLUSIONS
  Deficient endochondral ossification of the growth plate in the anterior upper corner of the vertebra could be the pathomechanism of the rounding deformity of the sacrum.
authors.affiliation: Department of Orthopedics, Institute of Health Biosciences, The University of Tokushima Graduate School, 3-18-15, Kuramoto, Tokushima 770-8503, Japan.
authors.forename: Kosaku
authors.initials: K
authors.lastname: Higashino
authors.forename: Koichi
authors.initials: K
authors.lastname: Sairyo
authors.forename: Tadanori
authors.initials: T
authors.lastname: Sakamaki
authors.forename: Shinji
authors.initials: S
authors.lastname: Komatsubara
authors.forename: Kiminori
authors.initials: K
authors.lastname: Yukata
authors.forename: Naohito
authors.initials: N
authors.lastname: Hibino
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Kosaka
authors.forename: Toshinori
authors.initials: T
authors.lastname: Sakai
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Katoh
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Sano
authors.forename: Natsuo
authors.initials: N
authors.lastname: Yasui
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism; D000367:Age Factors; D000818:Animals; D002356:Cartilage / Q000378:metabolism / Q000473:pathology*; D019902:Chondrocytes / Q000378:metabolism / Q000473:pathology*; D024043:Collagen Type II / Q000378:metabolism; D024121:Collagen Type X / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D006132:Growth Plate / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology*; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000378:metabolism; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D009999:Ossification, Heterotopic / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology*; D011859:Radiography; D051381:Rats; D017208:Rats, Wistar; D013168:Spondylolisthesis / Q000000981:diagnostic imaging / Q000201:enzymology / Q000378:metabolism / Q000473:pathology*; D000071681:Tartrate-Resistant Acid Phosphatase; D013997:Time Factors
chemical_list: D024043:Collagen Type II; D024121:Collagen Type X; D007527:Isoenzymes; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase