title: Intraosseous ultrasonography to determine the accuracy of drill hole positioning prior to the placement of pedicle screws: an experimental study.
abstract: OBJECTIVE
  Dorsal fixation with rods and pedicle screws (PSs) is the most frequently used surgery to correct traumatic and degenerative instabilities of the human spine. Prior to screw placement, screw holes are drilled along the vertebral pedicles. Despite the use of a variety of techniques, misplacement of screw holes, and consequently of the PSs, is a common problem. The authors investigated the usefulness of an intraspinal, intraosseous ultrasonography technique to determine the accuracy of drill hole positioning.
  
  
  METHODS
  An endovascular ultrasound transducer was used for the intraluminal scanning of bore holes in trabecular bovine bone, 12 pedicle drill holes in cadaveric human spine, and 4 pedicle drill holes in a patient undergoing thoracic spondylodesis. Seven of the experimental bore holes in the cadaveric spine were placed optimally (that is, inside the pedicle) and 5 were placed suboptimally (breaching the medial or lateral cortical surface of the pedicle). Computed tomography scans were obtained in the patient and cadaveric specimen after the procedure.
  
  
  RESULTS
  The image quality achieved in examinations of native bovine bone tissue, the formalin-fixed human spine specimen, and human vertebrae in vivo was equal. The authors endosonographically identified correct intrapedicular and intravertebral positions as well as poor (cortex breached) placement of drill holes.
  
  
  CONCLUSIONS
  Intraosseous ultrasonography is a promising technique for the investigation of PS holes prior to screw implantation, and may add to the safety of PS placement.
authors: Department of Neurosurgery, Georg-August-University Göttingen, Göttingen, Germany. sven.kantelhardt@web.de
authors: Sven Rainer
authors: SR
authors: Kantelhardt
authors: Jörg
authors: J
authors: Larsen
authors: Volker
authors: V
authors: Bockermann
authors: Wolfgang
authors: W
authors: Schillinger
authors: Alf
authors: A
authors: Giese
authors: Veit
authors: V
authors: Rohde
mesh_terms: D000818:Animals; D001863:Bone Screws; D002417:Cattle; D015299:Discitis / Q000000981:diagnostic imaging / Q000601:surgery*; D005471:Fluoroscopy; D006801:Humans; D013123:Spinal Fusion / Q000379:methods*; D016896:Treatment Outcome; D018084:Ultrasonography, Interventional