title: [Biomechanical aspects of vertebral augmentation].
abstract: BACKGROUND
  With increasing age, bone mass decreases and the structure of the cancellous bone in the vertebral body changes. Especially in osteoporotic patients, but also with metastases in the vertebral body, this leads to decreased strength and, thus, to an increased risk of vertebral fractures. It is expected that this problem will increase significantly because of demographic developments. To treat or to prevent such vertebral fractures, different augmentation techniques have been developed. They can mainly be divided into vertebroplasty or kyphoplasty procedures.
  
  
  OBJECTIVE
  The goal of this paper is to summarize biomechanical aspects of these augmentations procedures and to present some alternative methods.
  
  
  METHODS
  With vertebroplasty, the loss of bone mass is balanced by injecting bone cement which improves the failure strength of the affected vertebral body. With kyphoplasty, cavities are created and these are filled with bone cement.
  
  
  RESULTS
  Disadvantages of vertebroplasty are uncontrollable cement extrusion and increased fracture risk in the adjacent vertebral bodies. With balloon kyphoplasty, the adjacent cancellous bone is compacted during dilation and, thus, does not allow good integration with the remaining trabeculae. In addition, this method is associated with an increased risk of fracture in the adjacent vertebrae. To counter these disadvantages, a number of new types of cement and alternative augmentation methods are being developed, with which the vertebral body may be filled or distracted.
  
  
  CONCLUSIONS
  The efficacy of these new methods should be tested in appropriate experimental biomechanical studies before they are used in patients.
authors.affiliation: Institut für Unfallchirurgische Forschung und Biomechanik, Zentrum für Muskuloskelettale Forschung Ulm (ZMFU), Universitätsklinikum Ulm, Helmholtzstr. 14, 89081, Ulm, Deutschland. hans-joachim.wilke@uni-ulm.de.
authors.forename: H-J
authors.initials: HJ
authors.lastname: Wilke
mesh_terms: D001843:Bone Cements / Q000627:therapeutic use*; D019245:Compressive Strength; D006801:Humans; D010027:Osteotomy / Q000295:instrumentation / Q000379:methods*; D019651:Plastic Surgery Procedures / Q000295:instrumentation / Q000379:methods; D016103:Spinal Fractures / Q000503:physiopathology* / Q000628:therapy*; D013718:Tensile Strength; D016896:Treatment Outcome; D054854:Vertebroplasty / Q000295:instrumentation / Q000379:methods*
chemical_list: D001843:Bone Cements
keywords: Biomechanical phenomena; Bone fractures; Cement extrusion; Kyphoplasty; Vertebroplasty