title: Ex vivo experiments of a new injection cannula for vertebroplasty.
abstract: METHODS
  An experimental study using cadaveric vertebrae.
  
  
  OBJECTIVE
  To measure the injection pressure in an ex vivo model and determine whether the redesigned cannula, featuring 2 distinct sections of different diameters, significantly reduces the injection pressure.
  
  
  BACKGROUND
  An important limitation of vertebroplasty is the excessive pressure required to inject sufficient cement. The redesigned cannula accounts for the "bottleneck" of the injection previously identified. It has a distal section that is adapted to the pedicles and a proximal section with a larger diameter.
  
  
  METHODS
  Two cannulas were tested, a conventional 8-gauge and the redesigned cannula. There were 3 mL of cement injected in small strokes of 0.75 mL into the left and right hemivertebrae. A custom-made injection device monitored the injection pressure and cement volume.
  
  
  RESULTS
  Average injection pressure was 2.3 MPa, often approaching the human physical limit and resulting in insufficient filling. The average pressure of the redesigned cannula was 44% lower than that of the conventional cannula, a highly significant result (P < 0.001).
  
  
  CONCLUSIONS
  The new cannula may improve vertebroplasty by significantly easing cement injection. It is cost effective and can be easily integrated into the existing procedure.
authors.affiliation: Laboratoire de biomécanique, Génie mécanique, Université de Sherbrooke, Québec, Canada. Gamal.Baroud@USherbrooke.ca
authors.forename: Gamal
authors.initials: G
authors.lastname: Baroud
authors.forename: Pierre-Luc
authors.initials: PL
authors.lastname: Martin
authors.forename: François
authors.initials: F
authors.lastname: Cabana
mesh_terms: D001178:Arthroplasty / Q000295:instrumentation* / Q000379:methods; D001843:Bone Cements / Q000627:therapeutic use*; D015519:Bone Density; D002404:Catheterization / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D006801:Humans; D007267:Injections; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery; D011859:Radiography; D013131:Spine / Q000601:surgery*; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery
chemical_list: D001843:Bone Cements