title: A biomechanical strength comparison of external fixators.
abstract: BACKGROUND
  The purpose of this study was to biomechanically test the current commercially available uniplanar, half-pin external fixators, comparing stiffness, weight, and cost.
  
  
  METHODS
  The Hammer, HexFix, Hoffmann, Monotube Blue, Monotube Red, Torus, TraumaFix, and Ultra-X were tested using previously published methods. The Instron 4500 was used to assess the strength characteristics in axial, torsional, anteroposterior, and lateral bending of each device. Weight was based on the unassembled fixator construct. Cost was determined from the purchase price of each individual fixator.
  
  
  RESULTS
  The results of this study revealed that the Torus was the stiffest external fixator tested in torsion. The Monotube Red was the stiffest in axial loading, anteroposterior bending, and lateral bending. The Hammer and Hoffmann external fixators were the heaviest constructs. The Torus and HexFix were the most expensive.
  
  
  CONCLUSIONS
  Many factors, including stiffness, weight, cost, ease of application, fracture characteristics, and personal preference, go into deciding which external fixator to use. The data presented compare stiffness characteristics of several fixators under standardized loading conditions. These data indicate that the Torus and Monotube Red provide the greatest stiffness when comparing all modes of failure.
authors.affiliation: Department of Orthopaedics, Dwight David Eisenhower Army Medical Center, Fort Gordon, Georgia 30905, USA.
authors.forename: S J
authors.initials: SJ
authors.lastname: Sladicka
authors.forename: S R
authors.initials: SR
authors.lastname: Duffin
authors.forename: J M
authors.initials: JM
authors.lastname: Erpelding
mesh_terms: D001696:Biomechanical Phenomena; D016267:External Fixators / Q000592:standards*; D006801:Humans; D011474:Prosthesis Design; D013718:Tensile Strength