title: Biomechanical analysis of a new expandable vertebral body replacement combined with a new polyaxial antero-lateral plate and/or pedicle screws and rods.
abstract: OBJECTIVE
  Restoration of the anterior spinal profile and regular load-bearing is the main goal treating anterior spinal defects in case of fracture. Over the past years, development and clinical usage of cages for vertebral body replacement have increased rapidly. For an enhanced stabilization of rotationally unstable fractures, additional antero-lateral implants are common. The purpose of this study was the evaluation of the biomechanical behaviour of a recently modified, in situ distractible vertebral body replacement (VBR) combined with a newly developed antero-lateral polyaxial plate and/or pedicle screws and rods using a full corpectomy model as fracture simulation.
  
  
  METHODS
  Twelve human spinal specimens (Th12-L4) were tested in a six-degree-of-freedom spine tester applying pure moments of 7.5 Nm to evaluate the stiffness of three different test instrumentations using a total corpectomy L2 model: (1) VBR+antero-lateral plate; (2) VBR, antero-lateral plate+pedicle screws and rods and (3) VBR+pedicle screws and rods.
  
  
  RESULTS
  In the presented total corpectomy defect model, only the combined antero-posterior instrumentation (VBR, antero-lateral plate+pedicle screws and rods) could achieve higher stiffness in all three-movement planes than the intact specimen. In axial rotation, neither isolated anterior instrumentation (VBR+antero-lateral plate) nor isolated posterior instrumentation (VBR+pedicle screws and rods) could stabilize the total corpectomy compared to the intact state.
  
  
  CONCLUSIONS
  For rotationally unstable vertebral body fractures, only combined antero-posterior instrumentation could significantly decrease the range of motion (ROM) in all motion planes compared to the intact state.
authors: BG Trauma Center, Department of Trauma and Reconstructive Surgery, Eberhard-Karls-University Tübingen, Schnarrenbergstrasse 95, 72076, Tuebingen, Germany.
authors: Benjamin
authors: B
authors: Ulmar
authors: Stefanie
authors: S
authors: Erhart
authors: Stefan
authors: S
authors: Unger
authors: Kuno
authors: K
authors: Weise
authors: Werner
authors: W
authors: Schmoelz
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena / Q000502:physiology; D001858:Bone Nails / Q000592:standards; D001860:Bone Plates / Q000592:standards; D001863:Bone Screws / Q000592:standards; D002102:Cadaver; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000502:physiology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D019919:Prosthesis Implantation / Q000379:methods; D016103:Spinal Fractures / Q000503:physiopathology / Q000601:surgery*; D013123:Spinal Fusion / Q000295:instrumentation* / Q000379:methods*; D013904:Thoracic Vertebrae / Q000502:physiology / Q000601:surgery*