title: Use of a screw-syringe injector for cement delivery during kyphoplasty: technical report.
abstract: OBJECTIVE
  Percutaneous kyphoplasty is postulated to have several advantages over percutaneous vertebroplasty for the treatment of vertebral compression fractures and is gaining increased popularity. However, cement delivery with the KyphX kit (Kyphon, Inc., Santa Clara, CA), the only commercially available device for percutaneous kyphoplasty, is relatively problematic. This kit uses a series of "bone filler device" (BFD) tubes. Each BFD must be loaded manually with cement, which is then injected into the kyphoplasty cavity by manually depressing an inner stylet. The high profile of the BFD cannulas and their stylets requires frequent repositioning of the image intensifier tube and table. Because each accommodates only a small volume, the BFDs must be exchanged frequently. This delivery method also places the operator's hands directly in the field of radiation. We sought to overcome these limitations.
  
  
  METHODS
  Dissatisfied with the shortcomings of the BFDs, we substituted the EZflow screw-syringe injector (Parallax Medical, Mountain View, CA) we use to deliver cement during conventional percutaneous vertebroplasty. This amalgam of the KyphX kit and the screw-syringe injector has been used for kyphoplasty treatment of 26 thoracolumbar compression fractures in 17 patients.
  
  
  RESULTS
  The screw-syringe injector allows controlled volumetric delivery of large boluses of high-viscosity cement without having to refill the reservoir. It minimizes radiation exposure and does not require repositioning of the x-ray tubes. It may theoretically allow decompression should cement extrusion occur. Also, it delivers cement to the interstices of bony trabeculae outside the kyphoplasty cavity, thus combining the mechanical benefits of percutaneous kyphoplasty and percutaneous vertebroplasty.
  
  
  CONCLUSIONS
  The use of a screw-syringe injector has several merits over the customary means of cement delivery during kyphoplasty.
authors.affiliation: Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, California, USA. amar@aya.yale.edu
authors.forename: Arun Paul
authors.initials: AP
authors.lastname: Amar
authors.forename: Donald W
authors.initials: DW
authors.lastname: Larsen
authors.forename: George P
authors.initials: GP
authors.lastname: Teitelbaum
mesh_terms: D001843:Bone Cements / Q000627:therapeutic use*; D001863:Bone Screws; D005593:Fracture Fixation, Internal / Q000379:methods*; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000293:injuries* / Q000601:surgery*; D011859:Radiography; D013117:Spinal Cord Compression / Q000000981:diagnostic imaging / Q000209:etiology* / Q000601:surgery*; D016103:Spinal Fractures / Q000150:complications* / Q000000981:diagnostic imaging / Q000601:surgery*; D013594:Syringes; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000293:injuries* / Q000601:surgery*
chemical_list: D001843:Bone Cements