title: Establishment of a femoral critical-size bone defect model in immunodeficient mice.
abstract: BACKGROUND
  The development of innovative therapies for bone regeneration requires the use of advanced site-specific bone defect small-animal models. The achievement of proper fixation with a murine model is challenging due to the small dimensions of the murine femur. The aim of this investigation was to find the optimal defect size for a murine critical-size bone defect model using external fixation method.
  
  
  METHODS
  An external fixation device was attached to the right femur of 30 mice. Femoral bone defects of 1 mm (n = 10), 2 mm (n = 10), and 3 mm (n = 10) were created. Wounds were closed without any additional treatment. To investigate bone healing during the 12-wk observation period, x-ray analysis, histomorphology, immunohistochemistry, and μCT scans were performed.
  
  
  RESULTS
  MicroCT analyses after 12 wk showed that 3/8 1-mm defects, 5/8 2-mm defects, and 8/8 3-mm defects remained as nonunions. The defect volumes were 0.36 ± 0.42 mm³ (1-mm group), 1.40 ± 0.88 mm³ (2-mm group), and 2.88 ± 0.28 mm³ (3-mm group; P < 0.001, between all groups).
  
  
  CONCLUSIONS
  Using external fixation, a defect size of 3 mm is necessary to reliably create a persisting femoral bone defect in nude mice.
authors: Department of Orthopedic Surgery, Stanford University, Stanford, California; Department of Orthopaedics and Centre for Translational Bone, Joint and Soft Tissue Research, University Hospital Carl Gustav Carus at Technical University Dresden, Germany. stefan.zwingenberger@uniklinikum-dresden.de
authors: Stefan
authors: S
authors: Zwingenberger
authors: Eik
authors: E
authors: Niederlohmann
authors: Corina
authors: C
authors: Vater
authors: Stefan
authors: S
authors: Rammelt
authors: Romano
authors: R
authors: Matthys
authors: Ricardo
authors: R
authors: Bernhardt
authors: Roberto Daniel
authors: RD
authors: Valladares
authors: Stuart Barry
authors: SB
authors: Goodman
authors: Maik
authors: M
authors: Stiehler
mesh_terms: D000818:Animals; D016267:External Fixators; D005269:Femur / Q000293:injuries / Q000601:surgery*; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D023421:Models, Animal; D023822:Tissue Engineering; D055114:X-Ray Microtomography