title: The fixation strength of scaphoid bone screws: an in vitro investigation using polyurethane foam.
abstract: OBJECTIVE
  To compare the compression strength and pull-apart resistance of 5 single-piece scaphoid bone compression screws (Acutrak, Asnis, Herbert, Herbert-Whipple, and Little Grafter), with those of 2 dual-component screws (Kompressor and TwinFix).
  
  
  METHODS
  Two blocks of polyurethane foam were compressed with a screw while held in a tension test machine, with the force measured at full insertion of the screw. The 2 blocks were then pulled apart, and the maximum resistive force was measured.
  
  
  RESULTS
  The dual-component screws (Kompressor and TwinFix) gave greater compression force than the single-component screws, with the Kompressor screw giving statistically significantly greater compression than the TwinFix. The pull-apart resistance forces did not show such clear differences.
  
  
  CONCLUSIONS
  The Kompressor screw achieves the greatest compressive forces and has one of the highest pull-apart forces.
  
  
  CONCLUSIONS
  When compression and pull-apart resistance are considered, the Kompressor screw has advantages over other methods of scaphoid fixation.
authors.affiliation: Centre for Hand and Upper Limb Surgery, Wigan, Lancashire, UK.
authors.forename: Louise A
authors.initials: LA
authors.lastname: Crawford
authors.forename: Eric S
authors.initials: ES
authors.lastname: Powell
authors.forename: Ian A
authors.initials: IA
authors.lastname: Trail
mesh_terms: D001863:Bone Screws; D019245:Compressive Strength; D004867:Equipment Design; D004868:Equipment Failure; D006801:Humans; D008953:Models, Anatomic; D011140:Polyurethanes; D021361:Scaphoid Bone / Q000601:surgery*; D013718:Tensile Strength
chemical_list: D011140:Polyurethanes; C028279:polyurethane foam