Intra-osseous ultrasound for pedicle screw positioning in the subaxial cervical spine: an experimental study.
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.
Kantelhardt
Sven Rainer
SR
Department of Neurosurgery, Georg August University of Göttingen, 37075 Göttingen, Germany. sven.kantelhardt@web.de
Bock
Hans Christoph
HC
Siam
Laila
L
Larsen
Jörg
J
Burger
Ralf
R
Schillinger
Wolfgang
W
Bockermann
Volker
V
Rohde
Veit
V
Giese
Alf
A
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*