title: Intra-osseous ultrasound for pedicle screw positioning in the subaxial cervical spine: an experimental study.
abstract: BACKGROUND
  In contrast to other regions of the human spine, dorsal fixation with rods and pedicle screws is comparatively rarely performed in the cervical spine. Although this technique provides a higher mechanical strength than the more frequently used lateral mass screws, many surgeons fear the relatively high rate of misplacements. This higher incidence is mainly due to the complex vertebral anatomy in this spinal segment. For correct screw placement, the availability of an immediate and efficient intra-operative imaging tool to ascertain the accuracy of the pedicle screw hole position would be beneficial. We have previously investigated the usefulness of an intraspinal, specifically, intra-osseous ultrasound technique in the lumbar spine. In this study its accuracy as a means of controlling intrapedicular screw hole positioning has been evaluated in the cervical spine.
  
  
  METHODS
  An endovascular ultrasound transducer was used for the intra-luminal scanning of 54 pedicle screw holes in cadaveric human spine specimens. Twenty-three of these had been intentionally misplaced (cortex breached). The resulting image files were assessed by three investigators blinded to both the procedure and the corresponding CT findings.
  
  
  RESULTS
  The investigators differentiated correctly between adequately and poorly placed pedicle screw holes in 96% of cases. False negatives and false positives both occurred in no more than 1.8% of cases.
  
  
  CONCLUSIONS
  Intrapedicular ultrasonography of pedicle screw holes in the cervical spine is a promising technique for the intra-operative assessment of bore hole placement and may increase operative safety and postoperative outcome in posterior cervical fusion surgery.
authors: Department of Neurosurgery, Georg August University of Göttingen, 37075 Göttingen, Germany. sven.kantelhardt@web.de
authors: Sven Rainer
authors: SR
authors: Kantelhardt
authors: Hans Christoph
authors: HC
authors: Bock
authors: Laila
authors: L
authors: Siam
authors: Jörg
authors: J
authors: Larsen
authors: Ralf
authors: R
authors: Burger
authors: Wolfgang
authors: W
authors: Schillinger
authors: Volker
authors: V
authors: Bockermann
authors: Veit
authors: V
authors: Rohde
authors: Alf
authors: A
authors: Giese
mesh_terms: D001863:Bone Screws; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D004867:Equipment Design; D007431:Intraoperative Complications / Q000000981:diagnostic imaging* / Q000601:surgery*; D012680:Sensitivity and Specificity; D013123:Spinal Fusion / Q000295:instrumentation*; D014057:Tomography, X-Ray Computed; D014159:Transducers; D017211:Treatment Failure; D018084:Ultrasonography, Interventional / Q000295:instrumentation*