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Measurement of vertebral cortical integrity during pedicle exploration for intrapedicular fixation
B S Myers1, C C Hasty, D R Floberg
1Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA.
Study Design:
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.
Summary Of Background Data:
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.