title: Comparison of the bending performance of solid and cannulated spinal pedicle screws using finite element analyses and biomechanical tests.
abstract: Spinal pedicle screw fixations have been used extensively to treat fracture, tumor, infection, or degeneration of the spine. Cannulated spinal pedicle screws with bone cement augmentation might be a useful method to ameliorate screw loosening. However, cannulated spinal pedicle screws might also increase the risk of screw breakage. Thus, the purpose of this study was to investigate the bending performance of different spinal pedicle screws with either solid design or cannulated design. Three-dimensional finite element models, which consisted of the spinal pedicle screw and the screw's hosting material, were first constructed. Next, monotonic and cyclic cantilever bending tests were both applied to validate the results of the finite element analyses. Finally, both the numerical and experimental approaches were evaluated and compared. The results indicated that the cylindrical spinal pedicle screws with a cannulated design had significantly poorer bending performance. In addition, conical spinal pedicle screws maintained the original bending performance, whether they were solid or of cannulated design. This study may provide useful recommendations to orthopedic surgeons before surgery, and it may also provide design rationales to biomechanical engineers during the development of spinal pedicle screws.
authors.affiliation: Department of Orthopedic Surgery, Shin Kong Wu Ho-Su Memorial Hospital, Taipei 111, Taiwan, ROC ; College of Medicine, Fu Jen Catholic University, Taipei 242, Taiwan, ROC ; School of Medicine, Taipei Medical University, Taipei 110, Taiwan, ROC.
authors.forename: Kao-Shang
authors.initials: KS
authors.lastname: Shih
authors.affiliation: Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, No. 43, Sec. 4, Keelung Rd, Taipei 106, Taiwan, ROC . Electronic address: hsucc@mail.ntust.edu.tw.
authors.forename: Ching-Chi
authors.initials: CC
authors.lastname: Hsu
authors.affiliation: Department of Orthopedic Surgery, Shin Kong Wu Ho-Su Memorial Hospital, Taipei 111, Taiwan, ROC ; College of Medicine, Fu Jen Catholic University, Taipei 242, Taiwan, ROC ; School of Medicine, Taipei Medical University, Taipei 110, Taiwan, ROC.
authors.forename: Sheng-Mou
authors.initials: SM
authors.lastname: Hou
authors.affiliation: Graduate Institute of Biomedical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan, ROC.
authors.forename: Shan-Chuen
authors.initials: SC
authors.lastname: Yu
authors.affiliation: Department of Orthopedic Surgery, Shin Kong Wu Ho-Su Memorial Hospital, Taipei 111, Taiwan, ROC ; College of Medicine, Fu Jen Catholic University, Taipei 242, Taiwan, ROC.
authors.forename: Chen-Kun
authors.initials: CK
authors.lastname: Liaw
mesh_terms: D003198:Computer Simulation; D004867:Equipment Design; D004868:Equipment Failure; D020342:Finite Element Analysis; D008422:Materials Testing; D008962:Models, Theoretical; D065289:Pedicle Screws; D013131:Spine / Q000601:surgery*
keywords: Bending performance; Biomechanical test; Breakage; Cannulated pedicle screw; Finite element analysis