Fixation effects of different types of cannulated screws on vertical femoral neck fracture: A finite element analysis and experimental study

Shi Zhan, Dajun Jiang, Ming Ling, Jian Ding, Kai Yang, Lei Duan, Tsung Yuan Tsai, Yong Feng, Bart van Trigt, Weitao Jia*, Changqing Zhang, Hai Hu

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

Abstract

Femoral neck fractures (FNFs) in young patients usually result from high-energy violence, and the vertical transcervical type is typically challenging for its instability. FNFs are commonly treated with three cannulated screws (CS), but the role of screws type on fixation effects (FE) is unclear. The purpose of this study was to evaluate the FE of ten types of CS with different diameters, lengths, depths, and pitches of thread via finite element analysis which was validated by a biomechanical test. Ten vertical FNF models were grouped, fixed by ten types of CS, respectively, all in a parallel, inverted triangular configuration. Their FE were scored comprehensively from six aspects via an entropy evaluation method, as higher scores showed better results. For partial-thread screws, thread length and thread shape factor (TSF) are determinative factors on stability of FNF only if thread depth is not too thick, and they have less cut-out risk, better compression effects and better detached resistance of fracture than full-thread screws, whereas full-thread screws appear to have better shear and shortening resistance. A combination of two superior partial-thread screws and one inferior full-thread screw for vertical FNF may get optimal biomechanical outcomes. The type of cannulated screw is important to consider when treating vertical FNF.

Original languageEnglish
Pages (from-to)32-39
JournalMedical Engineering and Physics
Volume97
DOIs
Publication statusPublished - 2021

Bibliographical note

Accepted Author Manuscript

Keywords

  • Biomechanics
  • Finite element analysis
  • Types of screws
  • Vertical femoral neck fracture

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