title: Double-plating of ovine critical sized defects of the tibia: a low morbidity model enabling continuous in vivo monitoring of bone healing.
abstract: BACKGROUND
  Recent studies using sheep critical sized defect models to test tissue engineered products report high morbidity and complications rates. This study evaluates a large bone defect model in the sheep tibia, stabilized with two, a novel Carbon fibre Poly-ether-ether-ketone (CF-PEEK) and a locking compression plate (LCP) which could sustain duration for up to 6 month with an acceptable low complication rate.
  
  
  METHODS
  A large bone defect of 3 cm was performed in the mid diaphysis of the right tibia in 33 sheep. The defect was stabilised with the CF - PEEK plate and an LCP. All sheep were supported with slings for 8 weeks after surgery. The study was carried out for 3 months in 6 and for 6 months in 27 animals.
  
  
  RESULTS
  The surgical procedure could easily be performed in all sheep and continuous in vivo radiographic evaluation of the defect was possible. This long bone critical sized defect model shows with 6.1% a low rate of complications compared with numbers mentioned in the literature.
  
  
  CONCLUSIONS
  This experimental animal model could serve as a standard model in comparative research. A well defined standard model would reduce the number of experimental animals needed in future studies and would therefore add to ethical considerations.
authors.affiliation: AO Research Institute, Davos, Switzerland. ja.hahn@web.de
authors.forename: Joachim A
authors.initials: JA
authors.lastname: Hahn
authors.forename: Tanja S
authors.initials: TS
authors.lastname: Witte
authors.forename: Daniel
authors.initials: D
authors.lastname: Arens
authors.forename: Alexandra
authors.initials: A
authors.lastname: Pearce
authors.forename: Simon
authors.initials: S
authors.lastname: Pearce
mesh_terms: D023401:Animal Use Alternatives; D000818:Animals; D001577:Benzophenones; D001672:Biocompatible Materials / Q000009:adverse effects; D001860:Bone Plates; D002244:Carbon; D018483:Diaphyses / Q000000981:diagnostic imaging / Q000293:injuries / Q000601:surgery; D004195:Disease Models, Animal; D005593:Fracture Fixation, Internal / Q000295:instrumentation* / Q000379:methods*; D017102:Fracture Healing / Q000187:drug effects / Q000502:physiology; D007659:Ketones / Q000009:adverse effects; D008136:Longevity / Q000187:drug effects; D010012:Osteogenesis / Q000187:drug effects / Q000502:physiology; D011092:Polyethylene Glycols / Q000009:adverse effects; D011108:Polymers; D011183:Postoperative Complications; D011474:Prosthesis Design; D011859:Radiography; D012756:Sheep; D013977:Tibia / Q000000981:diagnostic imaging / Q000293:injuries / Q000601:surgery*
chemical_list: D001577:Benzophenones; D001672:Biocompatible Materials; D007659:Ketones; D011108:Polymers; C063834:polyetheretherketone; D011092:Polyethylene Glycols; D002244:Carbon