title: Mechanical properties of femoral trabecular bone in dogs.
abstract: BACKGROUND
  Studying mechanical properties of canine trabecular bone is important for a better understanding of fracture mechanics or bone disorders and is also needed for numerical simulation of canine femora. No detailed data about elastic moduli and degrees of anisotropy of canine femoral trabecular bone has been published so far, hence the purpose of this study was to measure the elastic modulus of trabecular bone in canine femoral heads by ultrasound testing and to assess whether assuming isotropy of the cancellous bone in femoral heads in dogs is a valid simplification.
  
  
  METHODS
  From 8 euthanized dogs, both femora were obtained and cubic specimens were cut from the centre of the femoral head which were oriented along the main pressure and tension trajectories. The specimens were tested using a 100 MHz ultrasound transducer in all three orthogonal directions. The directional elastic moduli of trabecular bone tissue and degrees of anisotropy were calculated.
  
  
  RESULTS
  The elastic modulus along principal bone trajectories was found to be 11.2 GPa +/- 0.4, 10.5 +/- 2.1 GPa and 10.5 +/- 1.8 GPa, respectively. The mean density of the specimens was 1.40 +/- 0.09 g/cm3. The degrees of anisotropy revealed a significant inverse relationship with specimen densities. No significant differences were found between the elastic moduli in x, y and z directions, suggesting an effective isotropy of trabecular bone tissue in canine femoral heads.
  
  
  CONCLUSIONS
  This study presents detailed data about elastic moduli of trabecular bone tissue obtained from canine femoral heads. Limitations of the study are the relatively small number of animals investigated and the measurement of whole specimen densities instead of trabecular bone densities which might lead to an underestimation of Young's moduli. Publications on elastic moduli of trabecular bone tissue present results that are similar to our data.
  
  
  CONCLUSIONS
  This study provides data about directional elastic moduli and degrees of anisotropy of canine femoral head trabecular bone and might be useful for biomechanical modeling of proximal canine femora.
authors.affiliation: Department of Orthopaedic Surgery, Hannover Medical School, Anna-von-Borries-Str, 1-7, 30625 Hannover, Germany. thomas.pressel@gmx.de
authors.forename: Thomas
authors.initials: T
authors.lastname: Pressel
authors.forename: Anas
authors.initials: A
authors.lastname: Bouguecha
authors.forename: Ute
authors.initials: U
authors.lastname: Vogt
authors.forename: Andrea
authors.initials: A
authors.lastname: Meyer-Lindenberg
authors.forename: Bernd-Arno
authors.initials: BA
authors.lastname: Behrens
authors.forename: Ingo
authors.initials: I
authors.lastname: Nolte
authors.forename: Henning
authors.initials: H
authors.lastname: Windhagen
mesh_terms: D000818:Animals; D016880:Anisotropy; D015519:Bone Density / Q000502:physiology*; D004285:Dogs; D004548:Elasticity; D005269:Femur / Q000000981:diagnostic imaging* / Q000502:physiology*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D066298:In Vitro Techniques; D013314:Stress, Mechanical; D014463:Ultrasonography; D016474:Weight-Bearing / Q000502:physiology*