title: A multi-level rapid prototyping drill guide template reduces the perforation risk of pedicle screw placement in the lumbar and sacral spine.
abstract: BACKGROUND
  The method of free-hand pedicle screw placement is generally safe although it carries potential risks. For this reason, several highly accurate computer-assisted systems were developed and are currently on the market. However, these devices have certain disadvantages. We have developed a method of pedicle screw placement in the lumbar and sacral region using a multi-level drill guide template, created with the rapid prototyping technology and have validated it in a clinical study. The aim of the study was to manufacture and evaluate the accuracy of a multi-level drill guide template for lumbar and first sacral pedicle screw placement and to compare it with the free-hand technique under fluoroscopy supervision.
  
  
  METHODS
  In 2011 and 2012, a randomized clinical trial was performed on 20 patients. 54 screws were implanted in the trial group using templates and 54 in the control group using the fluoroscopy-supervised free-hand technique. Furthermore, applicability for the first sacral level was tested. Preoperative CT-scans were taken and templates were designed using the selective laser sintering method. Postoperative evaluation and statistical analysis of pedicle violation, displacement, screw length and deviation were performed for both groups.
  
  
  RESULTS
  The incidence of cortex perforation was significantly reduced in the template group; likewise, the deviation and displacement level of screws in the sagittal plane. In both groups there was no significantly important difference in deviation and displacement level in the transversal plane as not in pedicle screw length. The results for the first sacral level resembled the main investigated group.
  
  
  CONCLUSIONS
  The method significantly lowers the incidence of cortex perforation and is therefore potentially applicable in clinical practice, especially in some selected cases. The applied method, however, carries a potential for errors during manufacturing and practical usage and therefore still requires further improvements.
authors: Department of Orthopaedic Surgery, UKC Maribor, Ljubljanska ulica 5, 2000 Maribor, Slovenia. matjaz.merc@gmail.com
authors: Matjaz
authors: M
authors: Merc
authors: Igor
authors: I
authors: Drstvensek
authors: Matjaz
authors: M
authors: Vogrin
authors: Tomaz
authors: T
authors: Brajlih
authors: Gregor
authors: G
authors: Recnik
mesh_terms: D001863:Bone Screws / Q000009:adverse effects*; D005260:Female; D005471:Fluoroscopy; D005593:Fracture Fixation, Internal / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D007049:Iatrogenic Disease / Q000517:prevention & control; D007431:Intraoperative Complications / Q000517:prevention & control*; D008161:Lumbosacral Region / Q000293:injuries / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D061646:Operative Time; D011446:Prospective Studies; D016103:Spinal Fractures / Q000601:surgery*; D013123:Spinal Fusion / Q000295:instrumentation / Q000379:methods*; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome