title: Histological and immunohistological analysis of degenerative changes in the cranial cruciate ligament in a canine model of excessive tibial plateau angle.
abstract: OBJECTIVE
  To create a canine model of excessive tibial plateau angle (eTPA) and assess the chondroid metaplasia and extracellular matrix alteration in the cranial cruciate ligament.
  
  
  METHODS
  Seven mature female Beagles were included. Cylindrical osteotomy was performed bilaterally in the proximal tibia. The TPA was increased to approximately 40° in the left tibia (eTPA stifle) and left unchanged in the right tibia (control stifle). Exercise stress was started at three months postoperatively, and at 12 months postoperatively the dogs were euthanatized and the cranial cruciate ligaments were collected. The specimens were subjected to haematoxylin and eosin staining to assess the ligamentocyte morphology and immunostaining to assess the type I (COLI), type II (COLII), and type III (COLIII) collagen, and the sry-type HMG box 9 (SOX9) staining.
  
  
  RESULTS
  Macroscopic cranial cruciate ligament injury was absent in six dogs but present in the eTPA stifle of one dog, which was excluded from the analysis. The ligamentocyte density decreased and the percentage of round ligamentocytes increased in the eTPA stifles. The COLII, COLIII, and SOX9 staining increased significantly and COLI deposition decreased in the eTPA stifles compared to the control stifle.
  
  
  CONCLUSIONS
  The extracellular matrix changed, COLI deposition decreased, and COLIII and SOX9 staining increased in the cranial cruciate ligament of the eTPA stifles. SOX9 may contribute to COLII synthesis in the extracellular matrix of the cranial cruciate ligament in eTPA stifles, and eTPA may promote chondroid metaplasia and extracellular matrix alteration.
authors.affiliation: T. Ichinohe, Laboratory of Veterinary Surgery, Nippon Veterinary and Life Science University, 1-7-1 Kyounan, Musashino, Tokyo 180-8602, Japan, Phone: +81 422 314 151, Fax: +81 367 341 944, E-mail: tom.ichinohe@gmail.com.
authors.forename: T
authors.initials: T
authors.lastname: Ichinohe
authors.forename: N
authors.initials: N
authors.lastname: Kanno
authors.forename: Y
authors.initials: Y
authors.lastname: Harada
authors.forename: T
authors.initials: T
authors.lastname: Yogo
authors.forename: M
authors.initials: M
authors.lastname: Tagawa
authors.forename: Y
authors.initials: Y
authors.lastname: Hara
mesh_terms: D000818:Animals; D016118:Anterior Cruciate Ligament / Q000276:immunology / Q000473:pathology* / Q000601:surgery; D000070598:Anterior Cruciate Ligament Injuries; D004283:Dog Diseases / Q000276:immunology / Q000473:pathology* / Q000601:surgery; D004285:Dogs; D005260:Female; D010027:Osteotomy / Q000379:methods / Q000662:veterinary; D012421:Rupture; D013264:Stifle / Q000276:immunology / Q000473:pathology; D013977:Tibia / Q000276:immunology / Q000473:pathology* / Q000601:surgery
keywords: Cranial cruciate ligament; chondroid metaplasia; dog; excessive tibial plateau angle; extracellular matrix