title: Traumatic brain injury and bone healing: radiographic and biomechanical analyses of bone formation and stability in a combined murine trauma model.
abstract: BACKGROUND
  The combination of traumatic brain injury (TBI) and long-bone fractures has previously been reported to lead to exuberant callus formation. The aim of this experimental study was to radiographically and biomechanically study the effect of TBI on bone healing in a mouse model.
  
  
  METHODS
  138 female C57/Black6N mice were assigned to four groups (fracture (Fx) / TBI / combined trauma (Fx/TBI) / controls). Femoral osteotomy and TBI served as variables: osteotomies were stabilized with external fixators, TBI was induced with controlled cortical impact injury. During an observation period of four weeks, in vivo micro-CT scans of femora were performed on a weekly basis. Biomechanical testing of femora was performed ex vivo.
  
  
  RESULTS
  The combined-trauma group showed increased bone volume, higher mineral density, and a higher rate of gap bridging compared to the fracture group. The combined-trauma group showed increased torsional strength at four weeks.
  
  
  CONCLUSIONS
  TBI results in an increased formation of callus and mineral density compared to normal bone healing in mice. This fact combined with a tendency towards accelerated gap bridging leads to increased torsional strength. The present study underscores the empirical clinical evidence that TBI stimulates bone healing. Identification of underlying pathways could lead to new strategies for bone-stimulating approaches in fracture care.
authors.affiliation: Center for Musculoskeletal Surgery, Charité - University Medicine Berlin, Augustenburger Platz 1, 13353, Berlin, Germany.
authors.forename: R J
authors.initials: RJ
authors.lastname: Locher
authors.forename: T
authors.initials: T
authors.lastname: Lünnemann
authors.forename: A
authors.initials: A
authors.lastname: Garbe
authors.forename: K- D
authors.initials: K
authors.lastname: Schaser
authors.forename: K
authors.initials: K
authors.lastname: Schmidt-Bleek
authors.forename: G
authors.initials: G
authors.lastname: Duda
authors.forename: S
authors.initials: S
authors.lastname: Tsitsilonis
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002146:Bony Callus / Q000000981:diagnostic imaging*; D001930:Brain Injuries / Q000150:complications*; D004195:Disease Models, Animal; D005260:Female; D017102:Fracture Healing / Q000502:physiology*; D050723:Fractures, Bone / Q000150:complications*; D051379:Mice; D008810:Mice, Inbred C57BL; D010012:Osteogenesis / Q000502:physiology; D055114:X-Ray Microtomography