title: Murine model of oligotrophic tibial nonunion.
abstract: OBJECTIVE
  This study aimed to use modified distraction osteogenesis techniques to develop a reliable mouse fracture nonunion model with an oligotrophic phenotype.
  
  
  METHODS
  Twenty-six 10- to 14-week-old C57BL/6 male mice underwent a proximal diaphyseal tibial osteotomy with a 2-mm bone resection. An external fixation device was applied to the tibia using cerclage wires. A total of 2.25 mm of distraction was applied over 3 days, resulting in an average distraction gap of 4.28 mm. Plain radiographs were taken at regular intervals until euthanasia at 7 (n = 9), 10 (n = 13), or 12 (n = 4) weeks. After euthanasia, all samples were fixed in formalin, scanned with microcomputed tomography, decalcified in formic acid, prepared in paraffin, and stained with Alcian blue/Mayer's hematoxylin.
  
  
  RESULTS
  In the distraction groups, five mice were prematurely euthanized as a result of wound complications stemming from loss of distal fixation. Of the remaining 21, two healed, resulting in a 90% nonunion rate. These nonunions radiographically resembled clinical nonunions with tapered, cone-like fracture ends and histologically demonstrated evidence of attempted healing as seen with cartilage capping. Additionally, the plain radiographic appearance of those nonunions from mice euthanized at 10 and 12 weeks did not change over the final 4 to 6 weeks.
  
  
  CONCLUSIONS
  The use of 2-mm tibial resection osteotomy with 2-mm distraction provides a predictable model for fracture nonunion in mice with the oligotrophic phenotype closely resembling the clinical correlate. This model offers a promising means for characterization of the molecular events that occur during the development of fracture nonunion and for evaluation of noninvasive methods of nonunion rescue.
authors: Department of Orthopaedics and Rehabilitation, Strong Memorial Hospital, University of Rochester Medical Center, Rochester, NY, USA.
authors: Calvin T
authors: CT
authors: Hu
authors: Sarah C
authors: SC
authors: Offley
authors: Zaneb
authors: Z
authors: Yaseen
authors: Regis J
authors: RJ
authors: O'Keefe
authors: Catherine A
authors: CA
authors: Humphrey
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D017102:Fracture Healing; D017759:Fractures, Malunited / Q000000981:diagnostic imaging* / Q000473:pathology*; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D011859:Radiography; D013045:Species Specificity; D013978:Tibial Fractures / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000503:physiopathology