title: The reduction of endplate fractures during balloon vertebroplasty: a detailed radiological analysis of the treatment of burst fractures using pedicle screws, balloon vertebroplasty, and calcium phosphate cement.
abstract: METHODS
  In a human cadaveric burst fracture model, the amount of endplate fracture reduction after posterior instrumentation and balloon vertebroplasty was investigated quantitatively.
  
  
  OBJECTIVE
  To assess, in a burst fracture model, the vertebral body and adjacent disc heights, in parallel sagittal planes with 3-dimensional (3D) rotational x-ray imaging, at various phases during pedicle screw fixation and subsequent balloon vertebroplasty.
  
  
  BACKGROUND
  In recent human cadaveric thoracolumbar fracture studies, it was found that vertebral body height could be restored significantly with inflatable bone tamps. However, limited quantitative data exist on the amount of fracture reduction that can be achieved and how much of the reduction will be lost after deflation and removal of the bone tamps before the cement is injected.
  
  
  METHODS
  Twenty burst fractures were created and balloon vertebroplasty with calcium phosphate cement was performed after pedicle screw instrumentation. A 3D dataset was obtained during the following phases: intact, fractured, after reduction and stabilization with pedicle screws, after inflation of the balloons, after deflation and removal of the balloons, after injection of the cement. The fractured vertebral body and adjacent disc heights were measured from five reconstructed sagittal images and compared for the six phases of the procedure. Furthermore, the difference between the vertebral body height centrally and peripherally was calculated.
  
  
  RESULTS
  The mean vertebral body height at the thoracic level was Tintact = 19.5 +/- 2.2 mm, Tfractured = 14.6 +/- 3.8 mm, Treduction = 17.3 +/- 2.2 mm, Tinflation = 20.1 +/- 2.0 mm, Tdeflation = 18.0 +/- 2.0 mm, and Tcement = 17.8 +/- 1.8 mm. The overall change in vertebral body height between these phases was significant (P < 0.001). At the lumbar level the mean vertebral body height was Tintact = 23.2 +/- 3.8 mm, Tfractured = 14.7 +/- 3.0 mm, Treduction = 18.4 +/- 2.5 mm, Tinflation = 23.2 +/- 3.5 mm, Tdeflation = 19.3 +/- 2.3 mm, and Tcement = 20.2 +/- 2.8 mm. The overall change in MCVBH between these phases was also significant (P < 0.001). The increase in vertebral body height resulted in a decrease of the adjacent disc height. No difference was found for the amount of endplate reduction in the center or at the periphery. No leakage of cement was detected in the spinal canal.
  
  
  CONCLUSIONS
  Reduction of endplate fractures, both in the center and at the periphery, seems feasible and safe with combined fracture reduction and balloon vertebroplasty. The endplate fracture reduction that was gained by inflation of the bone tamps could not be maintained after deflation.
authors.affiliation: Department of Orthopaedics, University Medical Center Utrecht, Utrecht, The Netherlands. jj.verlaan@wxs.nl
authors.forename: Jorrit-Jan
authors.initials: JJ
authors.lastname: Verlaan
authors.forename: Everine B
authors.initials: EB
authors.lastname: van de Kraats
authors.forename: F Cumhur
authors.initials: FC
authors.lastname: Oner
authors.forename: Theo
authors.initials: T
authors.lastname: van Walsum
authors.forename: Wiro J
authors.initials: WJ
authors.lastname: Niessen
authors.forename: Wouter J A
authors.initials: WJ
authors.lastname: Dhert
mesh_terms: D000368:Aged; D001843:Bone Cements / Q000627:therapeutic use*; D001858:Bone Nails; D001863:Bone Screws; D002102:Cadaver; D002130:Calcium Phosphates / Q000627:therapeutic use*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000293:injuries* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D019637:Orthopedic Procedures; D011859:Radiography; D012399:Rotation; D016103:Spinal Fractures / Q000000981:diagnostic imaging / Q000601:surgery*; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000293:injuries* / Q000601:surgery
chemical_list: D001843:Bone Cements; D002130:Calcium Phosphates; C020243:calcium phosphate