Accurate placement of screws in spinal surgery is vital to mitigate risks like instability, nerve damage, or spinal cord injury, which can lead to various complications such as pain, sensory loss, muscle weakness, or paralysis below the injury site [33]. However, success rates in screw placement vary widely, ranging from 27.6% to 100% [56].
Advanced techniques, like pedicle screw placement (PSP) with enhanced guidance systems, aim to provide surgeons with better spatial awareness to prevent cortical breaches. Various guidance methods,
such as fluoroscopy, computer-assisted techniques, neurophysiological monitoring, and Electrical Impedance Spectroscopy (EIS) enabled by the PediGuard, have been developed and utilized in spinal fusion surgeries [18]. Despite their efficacy in reducing complications, these systems have limitations such as increased radiation exposure, prolonged surgery time, or lack of real-time feedback.
This study compares two sensing techniques, Electrical Impedance Spectroscopy (EIS)) and Diffuse Reflection Spectroscopy (DRS), for spinal fusion surgery. Both methods are employed to detect cortical
breaches during PSP by distinguishing between cancellous and cortical bone. Before experimentation, certain gaps in understanding must be addressed, including exploring the working principle of EIS for
vertebrae tissue and developing classifiers for both single and multiple frequencies. Additionally, efforts are made to create a vertebrae phantom with realistic electric and optical properties. EIS demonstrates an increase in impedance for cortical bone compared to cancellous bone due to the latter’s weblike structure with highly vascularized yellow bone marrow. Single-frequency analysis outperforms multiple-frequency analysis in distinguishing between vertebrae tissues. However, the development of a better model or the use of multiple single-frequency classifiers may enhance predictive
accuracy. Despite attempts to create an accurate vertebrae phantom, limitations in adjusting dielectric properties result in the utilization of the best-fit recipe.
Comparison between EIS and DRS reveals both are effective in detecting cortical breaches and tissues, with DRS exhibiting a longer look-ahead distance. EIS operates more like a step function, making it susceptible to distortions, suggesting DRS outperforms EIS in spinal fusion surgeries.