title: Forty-five-degree or higher insertion angles are required to penetrate the opposite cortex in bicortical applications of Kirschner wires: an in vitro study on sheep bones.
abstract: OBJECTIVE
  Slippage of the wires over the opposite cortex from the endosteal side is frequent and can lead to insufficient stability. This in vitro biomechanical study was planned to investigate the angle of wire insertion that leads to trans cortex perforation.
  
  
  METHODS
  Long bones of sheep were cut longitudinally into two pieces and half bones were stabilised on a frame. Three orthopaedic surgeons performed the experiment using ten wires of four different diameters at two different drilling speeds. Each wire was introduced from the endosteal side at angles starting at 30° in 5° increments until perforation. When perforation was achieved, the angle was recorded. To determinate the critical angle of perforation, receiver operating characteristic (ROC) curve analyses was performed. Two-way factorial analysis of variance (ANOVA) and Kruskal-Wallis tests were used for statistical comparisons.
  
  
  RESULTS
  Kirschner-wire insertion angles of ≥ 45° provided perforation with a percentage of 83.9 %. Wire diameter, drilling speed and surgeon variables had no effect on perforation angles (p > 0.05).
  
  
  CONCLUSIONS
  If preoperative evaluation of fractures to be fixed by K wires reveals the need for oblique wire insertion angle < 45°, a standard trocar-tip K wire application would lead to slippage of the wire tip on the endosteal surface of the opposite cortex. According to this study, the operative plan should be changed if such obliquity of the K wire is mandatory during bicortical applications.
authors.affiliation: School of Medicine, Department of Orthopaedics and Traumatology, University of Mersin, Mersin, Turkey. drmcolak@hotmail.com
authors.forename: Mehmet
authors.initials: M
authors.lastname: Colak
authors.forename: Burak
authors.initials: B
authors.lastname: Gurer
authors.forename: Mehmet Ali
authors.initials: MA
authors.lastname: Sungur
authors.forename: Metin Manouchehr
authors.initials: MM
authors.lastname: Eskandari
mesh_terms: D000818:Animals; D001864:Bone Wires; D005593:Fracture Fixation, Internal / Q000295:instrumentation* / Q000379:methods*; D050723:Fractures, Bone / Q000601:surgery*; D007593:Joint Instability / Q000517:prevention & control; D023421:Models, Animal; D012372:ROC Curve; D012756:Sheep / Q000502:physiology*