Fixation effects of different types of cannulated screws on vertical femoral neck fracture: A finite element analysis and experimental study. (November 2021)

• Record Type: Journal Article
• Authors: Zhan, Shi; Jiang, Dajun; Ling, Ming; Ding, Jian; Yang, Kai; Duan, Lei; Tsai, Tsung-Yuan; Feng, Yong; van Trigt, Bart; Jia, Weitao; Zhang, Changqing; Hu, Hai
• Is Part Of: Medical engineering & physics. Volume 97(2021)
• Page Start: 32
• Page End: 39
• Publication Date: 2021-11
• Subjects: Vertical femoral neck fracture -- Types of screws -- Finite element analysis -- Biomechanics; Biomedical engineering -- Periodicals; Biomedical Engineering -- Periodicals; Physics -- Periodicals; Génie biomédical -- Périodiques; Biomedical engineering; Electronic journals; Periodicals; 610.28
• DOI: 10.1016/j.medengphy.2021.09.007
• Languages: English
• ISSNs: 1350-4533

Abstract

Highlights: Fixation effects of ten types of common-used screws for vertical femoral neck fracture were analyzed biomechanically. The fixation performance of partial-thread screws was significantly better than that of full-thread screws, but full-thread screws showed excellent performance in protecting the FNF from shear and shortening. A combination of two superior partial-thread screws and one inferior full-thread screw for vertical FNF may get optimal biomechanical outcomes. Thread depth of partial-thread screws was found to be an important parameter which can affect the screws' fixation effects as important as thread length and thread shape factor (TSF). 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.