title: Three-dimensional finite element analysis used to compare six different methods of syndesmosis fixation with 3.5- or 4.5-mm titanium screws: a biomechanical study.
abstract: BACKGROUND
  Use of thicker and longer (four cortices) screws or of multiple screws seems to be more stable and efficient for syndesmosis fixation.
  
  
  METHODS
  A three-dimensional finite element model of an ankle was constructed from serial axial sections from an existing two-dimensional computed tomographic image. Constructions of syndesmosis fixation with 3.5-mm single tricortical, 3.5-mm single quadricortical, 3.5-mm double tricortical, 3.5-mm double quadricortical, 4.5-mm single tricortical, and 4.5-mm single quadricortical screws were performed on this model. Physiologic loads approximating those during stance phase normal walking were applied to this ankle system. Stress values on the screws using the six fixation methods were compared.
  
  
  RESULTS
  The highest maximum stress was determined over 3.5-mm cortical screws applied as single quadricortical, and the lowest maximum stress was determined over the 4.5-mm cortical screw applied as single quadricortical. Stress on the 3.5-mm single screw with quadricortical application was found to be higher than that with tricortical application and also compared with the 4.5-mm quadricortical screw application. Differences between the 4.5-mm single tricortical and quadricortical screws and between the 3.5-mm single tricortical and 3.5-mm double tricortical screw applications were not significant.
  
  
  CONCLUSIONS
  Quadricortical application of 3.5-mm single screws and tricortical application of 3.5-mm double cortical screws are not good choices for syndesmosis fixation. If the plan is tricortical application, a 3.5-mm single cortical screw is adequate. If quadricortical application of syndesmosis fixation is planned, a 4.5-mm cortical screw should be used.
authors.affiliation: Department of Orthopedics and Traumatology, University of Afyon Kocatepe, School of Medicine, Afyonkarahisar, Turkey. mserhan2005@hotmail.com
authors.forename: Mehmet Serhan
authors.initials: MS
authors.lastname: Er
authors.forename: Ozgur
authors.initials: O
authors.lastname: Verim
authors.forename: Levent
authors.initials: L
authors.lastname: Altinel
authors.forename: Suleyman
authors.initials: S
authors.lastname: Tasgetiren
mesh_terms: D001696:Biomechanical Phenomena; D001863:Bone Screws; D002102:Cadaver; D020342:Finite Element Analysis; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D050723:Fractures, Bone; D006801:Humans; D021621:Imaging, Three-Dimensional; D008422:Materials Testing / Q000379:methods; D015203:Reproducibility of Results; D014025:Titanium
chemical_list: D014025:Titanium