title: Effect of Augmentation Material Stiffness on Adjacent Vertebrae after Osteoporotic Vertebroplasty Using Finite Element Analysis with Different Loading Methods.
abstract: BACKGROUND
  Vertebroplasty is an effective treatment for osteoporotic vertebral fractures, which are one of the most common fractures associated with osteoporosis. However, clinical observation has shown that the risk of adjacent vertebral body fractures may increase after vertebroplasty. The mechanism underlying adjacent vertebral body fracture after vertebroplasty is not clear; excessive stiffness resulting from polymethyl methacrylate has been suspected as an important mechanism.
  
  
  OBJECTIVE
  The aim of our study was to compare the effects of bone cement stiffness on adjacent vertebrae after osteoporotic vertebroplasty under load-controlled versus displacement-controlled conditions.
  
  
  METHODS
  An experimental computer study using a finite element analysis.
  
  
  METHODS
  Medical research institute, university hospital, Korean.
  
  
  METHODS
  A three-dimensional digital anatomic model of L1/2 bone structure was reconstructed from human computed tomographic images. The reconstructed three-dimensional geometry was processed for finite element analysis such as meshing elements and applying material properties. Two boundary conditions, load-controlled and displacement-controlled methods, were applied to each of 5 deformation modes: compression, flexion, extension, lateral bending, and torsion.
  
  
  RESULTS
  The adjacent L1 vertebra, irrespective of augmentation, revealed nearly similar maximum von Mises stresses under the load-controlled condition. However, for the displacement-controlled condition, the maximum von Mises stresses in the cortical bone and inferior endplate of the adjacent L1 vertebra increased significantly after cement augmentation. This increase was more significant than that with stiffer bone cement under all modes, except the torsion mode.
  
  
  CONCLUSIONS
  The finite element model was simplified, excluding muscular forces and incorporating a large volume of bone cement, to more clearly demonstrate effects of bone cement stiffness on adjacent vertebrae after vertebroplasty.
  
  
  CONCLUSIONS
  Excessive stiffness of augmented bone cement increases the risk of adjacent vertebral fractures after vertebroplasty in an osteoporotic finite element model. This result was most prominently observed using the displacement-controlled method.
authors.forename: Ah-Reum
authors.initials: AR
authors.lastname: Cho
authors.affiliation: School of Mechanical Engineering, Kyungnam University, Changwon.
authors.forename: Sang-Bong
authors.initials: SB
authors.lastname: Cho
authors.affiliation: School of Mechanical Engineering, Kyungnam University, Changwon.
authors.forename: Jae-Ho
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Department of Anesthesia and Pain Medicine, School of Medicine, Pusan National University, Yangsan, Republic of Korea.
authors.forename: Kyung-Hoon
authors.initials: KH
authors.lastname: Kim
mesh_terms: D001843:Bone Cements / Q000592:standards* / Q000627:therapeutic use; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D008159:Lumbar Vertebrae / Q000601:surgery; D008422:Materials Testing / Q000379:methods / Q000592:standards*; D008875:Middle Aged; D008953:Models, Anatomic; D010024:Osteoporosis / Q000473:pathology / Q000601:surgery*; D019736:Prostheses and Implants / Q000592:standards; D016103:Spinal Fractures / Q000473:pathology / Q000601:surgery; D054854:Vertebroplasty / Q000592:standards*; D016474:Weight-Bearing
chemical_list: D001843:Bone Cements