title: Intraosseous ultrasound in the placement of pedicle screws in the lumbar spine.
abstract: METHODS
  Experimental and intraoperative evaluation of the efficiency of a novel technique.
  
  
  OBJECTIVE
  To determine the accuracy of pedicle screw hole placements before screw implantation in the lumbar spine.
  
  
  BACKGROUND
  Deviations from planned trajectories occur in a significant number of screw placements in posterior lumbar fixation. Several techniques have been proposed to minimize this complication, although none has gained general acceptance. This may be due to costs associated with their implementation or considerably extended operating times required by some techniques.
  
  
  METHODS
  Pedicle screw holes were placed in 24 pedicles of 2 postmortem human lumbar spine specimens. Sixteen optimal trajectories were placed and 8 intentional cortical breaches. Each pedicular drill hole was examined using a 360 degrees ultrasound transducer and CT scanning. The ultrasonographic images were reviewed by 3 independent investigators who were blinded to the CT findings. In addition, 20 screw holes were placed intraoperatively in 3 patients, and equally assessed by intraoperative intraosseous ultrasonography and postoperative CT scanning.
  
  
  RESULTS
  Ultrasonographic images of pedicle screw holes in postmortem human spine specimen were correctly interpreted in 99% of cases. No cortical breech was missed, i.e., no false-negatives occurred. Intraoperative findings closely matched the experimental data. None of the intraoperative ultrasound scans demonstrated a cortical breach, a finding confirmed by postoperative CT. The intraoperative time required for the ultrasonographic analysis of each pedicle was about 1 minute and the interpretation of the resulting images was judged intuitive by the evaluating neurosurgeons.
  
  
  CONCLUSIONS
  Intraosseous ultrasound is a highly reliable technique for the intraoperative assessment of pedicle screw holes before pedicle screw placement. Additional expenses with respect to procedure time and manpower are minimal.
authors.affiliation: Department of Neurosurgery, Georg-August-University Göttingen, Göttingen, Germany. sven.kantelhardt@web.de
authors.forename: Sven R
authors.initials: SR
authors.lastname: Kantelhardt
authors.forename: Christoph H
authors.initials: CH
authors.lastname: Bock
authors.forename: Jörg
authors.initials: J
authors.lastname: Larsen
authors.forename: Volker
authors.initials: V
authors.lastname: Bockermann
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Schillinger
authors.forename: Veit
authors.initials: V
authors.lastname: Rohde
authors.forename: Alf
authors.initials: A
authors.lastname: Giese
mesh_terms: D001863:Bone Screws; D002102:Cadaver; D005240:Feasibility Studies; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D019637:Orthopedic Procedures / Q000295:instrumentation* / Q000379:methods*; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D018084:Ultrasonography, Interventional