Measurement of vertebral cortical integrity during pedicle exploration for intrapedicular fixation.
METHODS
This study determined the predictive ability of electrical impedance measurement in detecting cortical perforation in a porcine model of pedicular exploration.


OBJECTIVE
This study tested the hypothesis that a large decrease in electrical impedance would occur as a result of perforation of the vertebral cortex by the pedicle probe.


BACKGROUND
The resistivity of cortical bone has been reported to be 25 to 100 times greater than that of soft tissues.


METHODS
A total of 42 pedicles of the lumbar spines of six swine were explored using the instrumented pedicle probes.


RESULTS
Using a 1 microAmp 30-Hz current source, measurement of electrical impedance predicted cortical rupture with a sensitivity, specificity, and accuracy of 95%. Maximum applied voltages of 2.8 mV did not result in myogenic stimulus.


CONCLUSIONS
Electrical impedance measurement provides an accurate real-time measurement of cortical perforation. This technique is adapted readily for use with pedicular screws and screw tape. Further investigation to determine the clinical use of this technique is recommended.
Myers
B S
BS
Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA.
Hasty
C C
CC
Floberg
D R
DR
Hoffman
R D
RD
Leone
B J
BJ
Richardson
W J
WJ
D000818:Animals; D001863:Bone Screws; D017097:Electric Impedance; D016268:Internal Fixators; D008159:Lumbar Vertebrae / Q000601:surgery*; D016343:Monitoring, Intraoperative / Q000295:instrumentation*; D013552:Swine