title: Effect of a supplemental plate on the stiffness of a type I external fixator.
abstract: OBJECTIVE
  To assess the effect of a supplemental plate on the stiffness of a six-pin unilateral external skeletal fixator.
  
  
  METHODS
  Mechanical testing performed on models.
  
  
  METHODS
  Wooden (birch) dowels were used to create five models of a fracture. A commercially available external fixation system was applied to the model with a uniform unilateral six-pin fixator design. The models were mechanically tested with and without a supplemental plate attached to the 2 clamps adjacent to the fracture gap. Testing was conducted in axial loading, medial to lateral bending, and cranial to caudal bending.
  
  
  RESULTS
  Results showed a 4.42-fold increase in stiffness in axial load, a 4.23-fold increase in stiffness in medial to lateral bending, and a 1.94-fold increase in stiffness in cranial to caudal bending with the addition of the plate.
  
  
  CONCLUSIONS
  The addition of a supplemental plate increases the mechanical stiffness of unilateral fixators. This was especially true in axial load and medial to lateral bending.
  
  
  CONCLUSIONS
  A supplemental plate can be used with unilateral fixators to increase stiffness of the fixator. Conversely, the plate can be removed to decrease stiffness without the removal of fixation pins.
authors.affiliation: Orthopedic Research Laboratory, Tufts University School of Veterinary Medicine, North Grafton, MA, USA.
authors.forename: Jana L
authors.initials: JL
authors.lastname: Norris
authors.forename: Karl H
authors.initials: KH
authors.lastname: Kraus
authors.forename: James P
authors.initials: JP
authors.lastname: O'Leary
mesh_terms: D000818:Animals; D004867:Equipment Design; D016267:External Fixators / Q000145:classification*; D005592:Fracture Fixation / Q000295:instrumentation / Q000662:veterinary*; D050723:Fractures, Bone / Q000601:surgery / Q000662:veterinary*; D008422:Materials Testing