title: Cement filling control and bone marrow removal in vertebral body augmentation by unipedicular aspiration technique: an experimental study using leakage model.
abstract: METHODS
  Experimental design using a laboratory leakage model.
  
  
  OBJECTIVE
  To examine that a new aspiration technique, with a double conduit cannula design, improves the uniformity of cement filling, thus significantly reducing the risk of extraosseous leakage.
  
  
  BACKGROUND
  In vertebral augmentation, understanding the forces governing the intravertebral cement flow is essential for controlling the cement formation. A path of least resistance posed by the irregularities in the bone matrix or vertebral shell increases the risk of leak. We have previously shown that using viscous cement reduces the leakage risk. However, this may damage the already weak bone due to the high forces required for the cement to enter the bone cavities.
  
  
  METHODS
  An experimental leakage model for vertebral augmentation was used-with a path, simulating a blood vessel, to provoke leakage. A novel cannula with 2 concentric conduits was used. The inner conduit is used for cement delivery and the outer conduit for aspiration. A mixed level with 2 factors (2 x 2(2)) experiment design was used to examine the ability of aspiration to direct the cement flow in both low and high viscous cement regimes.
  
  
  RESULTS
  Aspiration significantly enhanced the filling uniformity and reduced the risk of leakage. The reduction in leak with the suction simultaneous to the injection for low viscosity cement, elapsed time 4 minutes, was 1.5 cc (alpha = 0.05). In the suction experiments, the reduction in leakage as compared with the reference condition for the 8 minutes elapsed time was 0.5 cc, (alpha = 0.05).
  
  
  CONCLUSIONS
  The aspiration technique combined with a new cannula design improved the uniformity of filling. The aspiration technique helps in removal of the displaced bone marrow or tumor tissue. The aspiration applied with the new cannula requires only a single incision. Thus, it does not result in an increased invasiveness.
authors.affiliation: Biomechanics Laboratory, Mechanical Engineering Department, Université de Sherbrooke, Sherbrooke, QC, Canada.
authors.forename: Ramy
authors.initials: R
authors.lastname: Mohamed
authors.forename: Christian
authors.initials: C
authors.lastname: Silbermann
authors.forename: Ali
authors.initials: A
authors.lastname: Ahmari
authors.forename: Marc
authors.initials: M
authors.lastname: Bohner
authors.forename: Stephan
authors.initials: S
authors.lastname: Becker
authors.forename: Gamal
authors.initials: G
authors.lastname: Baroud
mesh_terms: D001843:Bone Cements / Q000737:chemistry; D001853:Bone Marrow / Q000601:surgery*; D002404:Catheterization / Q000295:instrumentation; D008954:Models, Biological; D054854:Vertebroplasty / Q000295:instrumentation* / Q000379:methods
chemical_list: D001843:Bone Cements