title: A mechanical comparison of 4.5 mm narrow and 3.5 mm broad plating systems for stabilization of gapped fracture models.
abstract: OBJECTIVE
  To evaluate and compare the mechanical properties of 4.5 narrow and 3.5 broad plating systems using their respective cortical and cancellous screws in unstable, central, and eccentric gap fracture models.
  
  
  METHODS
  Mechanical evaluation and comparison of 2 dynamic compression plate (DCP) systems.
  
  
  METHODS
  Eighteen cortical and 30 cancellous gapped fracture models.
  
  
  METHODS
  DCP (4.5 mm narrow, 3.5 mm broad) with their respective cortical screws were applied to cortical bone density polyurethane foam blocks to construct center gap cortical fracture models that were tested in gap closing monotonic 4-point bending. DCP (4.5 mm narrow, 3.5 mm broad) with their respective cancellous screws were applied to cancellous bone density polyurethane foam blocks to construct eccentric gap cancellous fracture models. The cancellous constructs were tested in monotonic gap opening and gap closing cantilever bending and in cyclic axial loading. Univariate and multivariate repeated measures ANOVA were used to compare the maximum loads at failure of the 4.5 mm constructs and 3.5 mm constructs.
  
  
  RESULTS
  The 4.5 mm narrow plating system withstood significantly higher loads at failure than the 3.5 mm broad plating system in 4-point bending (P<.0001) and gap opening cantilever bending (P<.0001). The 4.5 mm system failed in gap closing cantilever bending by plastic deformation of the plate, whereas the 3.5 mm system failed by screw pullout. There was no difference between the 2 systems in cyclic axial loading.
  
  
  CONCLUSIONS
  Results indicate that the 4.5 mm narrow plating system has a mechanical advantage over the 3.5 mm broad plating system for stabilization of gapped fracture models.
  
  
  CONCLUSIONS
  The 4.5 mm narrow plating system may be mechanically advantageous compared with the 3.5 mm broad plating system for stabilizing unreconstructed comminuted long bone fractures in large dogs.
authors.affiliation: Indianapolis Veterinary Specialists, Indianapolis, IN 46250-1512, USA. silbervets@aol.com
authors.forename: John T
authors.initials: JT
authors.lastname: Silbernagel
authors.forename: Ann L
authors.initials: AL
authors.lastname: Johnson
authors.forename: Gerald J
authors.initials: GJ
authors.lastname: Pijanowski
authors.forename: Nichole
authors.initials: N
authors.lastname: Ehrhart
authors.forename: David J
authors.initials: DJ
authors.lastname: Schaeffer
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D001863:Bone Screws / Q000662:veterinary; D004285:Dogs / Q000293:injuries* / Q000601:surgery*; D005264:Femoral Fractures / Q000601:surgery / Q000662:veterinary*; D005593:Fracture Fixation, Internal / Q000379:methods / Q000662:veterinary*