title: [Three-dimensional finite element analysis of biomechanical characteristics of cancellous screw in different bone densities].
abstract: OBJECTIVE
  To predict the cancellous screw stress distributions and pull-out strength in cancellous bone with different densities using 3-D finite element analysis and provide biomechanical evidence for screw implant in clinical practices.
  
  
  METHODS
  Three-dimensional models of bones with low, medium and high bone density and a fixation screw were generated in Solidworks. Finite element analysis was performed after importing these models to Abaqus to simulate the pull- out process.
  
  
  RESULTS
  Stress concentrated both at the surfaces where major diameter of the screw connected the bone and at the proximal half angle of the 3 proximal screw threads. Maximum Von Mises stress of the threads decreased along the long axis of the screw. The pull-out strengths of the cancellous screw were 208.9 N, 431.45 N, and 648.80 N in low, medium and high bone density, respectively.
  
  
  CONCLUSIONS
  During the pull-out process of cancellous screw, stress concentrates at the proximal end of the screw and the pull-out strengths are proportional to the cancellous bone density.
authors.affiliation: Department of Anatomy, Southern Medical University, Guangdong Provincial Medical Biomechanical Key Laboratory Guangdong, Guangzhou 510515, China. tianchong1985@yahoo.cn
authors.forename: Chong
authors.initials: C
authors.lastname: Tian
authors.forename: Mei-chao
authors.initials: MC
authors.lastname: Zhang
authors.forename: Jun
authors.initials: J
authors.lastname: Ouyang
mesh_terms: D001696:Biomechanical Phenomena; D015519:Bone Density; D001863:Bone Screws; D020342:Finite Element Analysis; D006801:Humans