title: In silico investigation of vertebroplasty as a stand-alone treatment for vertebral burst fractures.
abstract: The use of percutaneous vertebroplasty as a stand-alone treatment for stable vertebral burst fractures has been investigated in vitro and in clinical studies. These studies present inconsistent results on the mechanical response of vertebroplasty-treated burst fractures. In addition, observations of the loss of sagittal alignment after vertebroplasty raise questions on the applicability of vertebroplasty for burst fractures. Therefore, the aim of this study was to investigate the mechanical stability of burst fractures after stand-alone treatment by vertebroplasty.
  
  
  
  Finite element simulations were performed with models generated from two laboratory-induced burst fractures in human thoracolumbar specimens. The burst fracture models were virtually injected with various cement volumes using a unipedicular or bipedicular approach. The models were subjected to four individual loads (compression, lateral bending, extension and torsion) and a multi-axial load case in the physiological range.
  
  
  
  All treated burst fractures showed improvements in stiffness and a reduction in inter-fragmentary displacements, thus potentially providing a suitable mechanical environment for fracture healing. However, large volumes of the trabecular bone (<43%), cement (<53%) and bone-cement composite (<58%) were predicted to experience strain levels exceeding the yield point. While damage was not specifically modeled, this implies a potential collapse of the treated vertebra due to local failure.
  
  
  
  To improve the primary stability and to prevent the collapse of treated burst fractures, the use of posterior instrumentation is suggested as an adjunct to vertebroplasty.
authors.affiliation: Institute for Biomechanics, ETH-Zurich, Zurich, Switzerland. Electronic address: ikoh@ethz.ch.
authors.forename: Ilsoo
authors.initials: I
authors.lastname: Koh
authors.affiliation: Institute for Biomechanics, ETH-Zurich, Zurich, Switzerland.
authors.forename: Giacomo
authors.initials: G
authors.lastname: Marini
authors.affiliation: Institute for Biomechanics, ETH-Zurich, Zurich, Switzerland.
authors.forename: René P
authors.initials: RP
authors.lastname: Widmer
authors.affiliation: School of Mechanical Engineering, University of Leeds, Leeds, UK.
authors.forename: Nicola
authors.initials: N
authors.lastname: Brandolini
authors.affiliation: Institute for Biomechanics, ETH-Zurich, Zurich, Switzerland.
authors.forename: Benedikt
authors.initials: B
authors.lastname: Helgason
authors.affiliation: Institute for Biomechanics, ETH-Zurich, Zurich, Switzerland.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Ferguson
mesh_terms: D000368:Aged; D001843:Bone Cements / Q000627:therapeutic use; D003198:Computer Simulation; D005260:Female; D020342:Finite Element Analysis; D005593:Fracture Fixation, Internal / Q000379:methods; D006801:Humans; D008159:Lumbar Vertebrae / Q000293:injuries* / Q000503:physiopathology / Q000601:surgery; D016103:Spinal Fractures / Q000503:physiopathology* / Q000601:surgery*; D013314:Stress, Mechanical; D013904:Thoracic Vertebrae / Q000293:injuries* / Q000503:physiopathology / Q000601:surgery; D054854:Vertebroplasty / Q000379:methods*
chemical_list: D001843:Bone Cements
keywords: Biomechanics; Burst fracture; Finite-element; Vertebroplasty