title: An in vivo comparison of the potential for extravertebral cement leak after vertebroplasty and kyphoplasty.
abstract: METHODS
  A prospective in vivo study was conducted during the performance of kyphoplasty for the treatment of osteoporotic vertebral compression fractures, comparing extravertebral contrast extravasation with kyphoplasty and vertebroplasty.
  
  
  OBJECTIVE
  To determine the frequency and pattern of extravertebral contrast extravasation after intravertebral injection during kyphoplasty and vertebroplasty, which have implications for cement leakage during these procedures.
  
  
  BACKGROUND
  Vertebroplasty involves the injection of cement directly into the cancellous bone of a fractured vertebral body in an attempt to stabilize the fracture. High rates of extravertebral cement leakage have been noted. Injection of contrast into the vertebral body under fluoroscopy has been recommended in an attempt to predict and minimize cement leakage. An alternative procedure, balloon kyphoplasty, involves the percutaneous placement of an inflatable bone tamp into the fractured vertebral body. As the tamp is inflated, vertebral body height is restored and a cavity is created within the vertebral body, allowing for low-pressure cement filling of the cavity.
  
  
  METHODS
  During 20 kyphoplasty surgeries for vertebral compression fractures, contrast studies were performed. Immediately after positioning of an 11-gauge biopsy needle within the midvertebral body, 5 mL of Omnipaque was injected, mimicking vertebroplasty injection. Cinefluoroscopic images were obtained during injection. After bilateral fracture reduction and intravertebral cavity creation using inflatable bone tamps (kyphoplasty), contrast was injected again, mimicking cement injection during kyphoplasty. Scoring of the extravertebral contrast leakage was based on filling of the inferior vena cava and epidural vessels, as well as direct contrast extension through the vertebral cortex.
  
  
  RESULTS
  The mean contrast leak scores for vertebroplasty- and kyphoplasty-stage injections were, respectively, 4.3 and 0.8 of 6 (P = 0.0001). The scores for epidural vessel and inferior vena cava filling and transcortical contrast leak each was significantly lower for kyphoplasty- than for vertebroplasty-stage injections (P = 0.0001 each).
  
  
  CONCLUSIONS
  The findings showed less vascular and transcortical extravasation of injected contrast with kyphoplasty than with vertebroplasty. Although leakage of contrast may not correlate precisely with polymethylmethacrylate leakage, the authors believe this study highlights the relative safety of these procedures.
authors.affiliation: University of Chicago Spine Center, Chicago, Illinois 60640, USA. fphillip@weisshospital.org
authors.forename: Frank M
authors.initials: FM
authors.lastname: Phillips
authors.forename: F
authors.initials: F
authors.lastname: Todd Wetzel
authors.forename: Isadore
authors.initials: I
authors.lastname: Lieberman
authors.forename: Marrion
authors.initials: M
authors.lastname: Campbell-Hupp
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001843:Bone Cements / Q000009:adverse effects / Q000627:therapeutic use*; D002933:Cineradiography; D005119:Extravasation of Diagnostic and Therapeutic Materials / Q000150:complications / Q000175:diagnosis* / Q000000981:diagnostic imaging; D006801:Humans; D007431:Intraoperative Complications / Q000175:diagnosis / Q000209:etiology; D007738:Kyphosis / Q000209:etiology / Q000628:therapy*; D008875:Middle Aged; D019637:Orthopedic Procedures / Q000009:adverse effects; D010024:Osteoporosis / Q000150:complications; D011446:Prospective Studies; D016103:Spinal Fractures / Q000209:etiology / Q000628:therapy*; D013131:Spine / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000601:surgery
chemical_list: D001843:Bone Cements