title: Analysis of biomechanical changes after removal of instrumentation in lumbar arthrodesis by finite element analysis.
abstract: The purpose of this study is to investigate the change in biomechanical milieu following removal of pedicle screws in instrumented single level lumbar arthrodesis. Using a validated finite element (FE) model of the intact lumbar spine (L2-5), two scenarios of L3-4 lumbar fusion were simulated: posterolateral fusion (PLF) at L3-4 using pedicle screws (PLF with pedicle screws; WiP) and L3-4 lumbar posterolateral fusion state after removal of pedicle screws (PLF without pedicle screws; WoP). The WiP model had greater range of motion (ROM) at each adjacent segment than the WoP model. This phenomenon became pronounced at the proximal adjacent segment under flexion moment. Similarly, removal of pedicle screws (the WoP model) relieved the maximal von Mises stress at adjacent segments under 4 moments compared to the WiP model. This study demonstrated that removal of pedicle screws could decrease stiffness of fusion segments, which would reduce the disk stress of adjacent segments.
authors.affiliation: Yonsei sarang Hospital, Seoul, Korea.
authors.forename: Ho-Joong
authors.initials: HJ
authors.lastname: Kim
authors.forename: Heoung-Jae
authors.initials: HJ
authors.lastname: Chun
authors.forename: Seong-Hwan
authors.initials: SH
authors.lastname: Moon
authors.forename: Kyoung-Tak
authors.initials: KT
authors.lastname: Kang
authors.forename: Hak-Sun
authors.initials: HS
authors.lastname: Kim
authors.forename: Jin-Oh
authors.initials: JO
authors.lastname: Park
authors.forename: Eun-Su
authors.initials: ES
authors.lastname: Moon
authors.forename: Joon-Seok
authors.initials: JS
authors.lastname: Sohn
authors.forename: Hwan-Mo
authors.initials: HM
authors.lastname: Lee
mesh_terms: D001696:Biomechanical Phenomena; D001863:Bone Screws; D020878:Device Removal; D020342:Finite Element Analysis; D006801:Humans; D008159:Lumbar Vertebrae / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D016059:Range of Motion, Articular; D013123:Spinal Fusion / Q000295:instrumentation*