title: Biomechanical comparison of the K-ROD and Dynesys dynamic spinal fixator systems - a finite element analysis.
abstract: Dynamic spinal fixators, such as the Dynesys (DY) and K-ROD (KD) systems, are designed to restore spinal stability and to provide flexibility. The long-term complications of implant breakage and the biomechanics of the adjacent and the bridged levels using the KD system are still unknown. Therefore, this study aims to investigate and compare the biomechanical effects of the KD system and the DY system. Finite element (FE) models of the degenerated lumbar spine, the DY system, and the KD system were each reconstructed. Hybrid-controlled analysis was applied in the three FE models. The FE results indicated that the KD system supplies the most stiffness during extension and the least stiffness during flexion, in contrast to the DY system. In contrast to the DY system, the KD system increased the facet contact force of the adjacent level, but this system decreased the screw stress on the cranial adjacent disc and the pedicle during flexion.
authors.affiliation: Department of Mechanical Engineering, National Taiwan University, Taipei, Taiwan.
authors.forename: Hung-Ming
authors.initials: HM
authors.lastname: Lin
authors.forename: Yung-Ning
authors.initials: YN
authors.lastname: Pan
authors.forename: Chien-Lin
authors.initials: CL
authors.lastname: Liu
authors.forename: Li-Ying
authors.initials: LY
authors.lastname: Huang
authors.forename: Chang-Hung
authors.initials: CH
authors.lastname: Huang
authors.forename: Chen-Sheng
authors.initials: CS
authors.lastname: Chen
mesh_terms: D001696:Biomechanical Phenomena; D020342:Finite Element Analysis; D006801:Humans; D016268:Internal Fixators; D008159:Lumbar Vertebrae / Q000033:anatomy & histology* / Q000737:chemistry / Q000601:surgery; D008953:Models, Anatomic; D008954:Models, Biological; D013314:Stress, Mechanical
keywords: Dynesys; Finite element analysis; K-ROD system; biomechanics; dynamic spinal stabilization devices