title: Histopathological features of bone regeneration in a canine segmental ulnar defect model.
abstract: BACKGROUND
  Today, finding an ideal biomaterial to treat the large bone defects, delayed unions and non-unions remains a challenge for orthopaedic surgeions and researchers. Several studies have been carried out on the subject of bone regeneration, each having its own advantages. The present study has been designed in vivo to evaluate the effects of cellular auto-transplantation of tail vertebrae on healing of experimental critical bone defect in a dog model.
  
  
  METHODS
  Six indigenous breeds of dog with 32 ± 3.6 kg average weight from both sexes (5 males and 1 female) received bilateral critical-sized ulnar segmental defects. After determining the health condition, divided to 2 groups: The Group I were kept as control I (n = 1) while in Group II (experimental group; n = 5) bioactive bone implants were inserted. The defects were implanted with either autogeneic coccygeal bone grafts in dogs with 3-4 cm diaphyseal defects in the ulna. Defects were stabilized with internal plate fixation, and the control defects were not stabilized. Animals were euthanized at 16 weeks and analyzed by histopathology.
  
  
  RESULTS
  Histological evaluation of this new bone at sixteen weeks postoperatively revealed primarily lamellar bone, with the formation of new cortices and normal-appearing marrow elements. And also reformation cortical compartment and reconstitution of marrow space were observed at the graft-host interface together with graft resorption and necrosis responses. Finally, our data were consistent with the osteoconducting function of the tail autograft.
  
  
  CONCLUSIONS
  Our results suggested that the tail vertebrae autograft seemed to be a new source of autogenous cortical bone in order to supporting segmental long bone defects in dogs. Furthermore, cellular autotransplantation was found to be a successful replacement for the tail vertebrae allograft bone at 3-4 cm segmental defects in the canine mid- ulna. Clinical application using graft expanders or bone autotransplantation should be used carefully and requires further investigation.
  The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/2028232688119271.
authors.forename: Rahim
authors.initials: R
authors.lastname: Hobbenaghi
authors.forename: Pariya
authors.initials: P
authors.lastname: Mahboob
authors.forename: Siamak
authors.initials: S
authors.lastname: Saifzadeh
authors.affiliation: Department of Pathobiology, Faculty of Veterinary Medicine, Tehran University, Tehran, Iran. javadpatho@gmail.com.
authors.forename: Javad
authors.initials: J
authors.lastname: Javanbakht
authors.forename: Javad Yaghoobi Yeganeh
authors.initials: JY
authors.lastname: Manesh
authors.forename: Rasool
authors.initials: R
authors.lastname: Mortezaee
authors.forename: Seyed Rashid
authors.initials: SR
authors.lastname: Touni
authors.forename: Ehsan
authors.initials: E
authors.lastname: Hosseini
authors.forename: Shahin
authors.initials: S
authors.lastname: Aghajanshakeri
authors.forename: Milad
authors.initials: M
authors.lastname: Moloudizargari
authors.forename: Soheil
authors.initials: S
authors.lastname: Javaherypour
mesh_terms: D000818:Animals; D001861:Bone Regeneration / Q000502:physiology*; D016025:Bone Transplantation / Q000379:methods*; D004195:Disease Models, Animal; D004285:Dogs; D005260:Female; D008297:Male; D014182:Transplantation, Autologous; D014457:Ulna