Related Experiment Video
Updated: May 1, 2026
An Anesthesia, Surgery, and Harvest Method for the Evaluation of Transpedicular Screws Using an In Vivo Porcine Lumbar Spine Model
Published on: May 31, 2017
Can triggered electromyography be used to evaluate pedicle screw placement in hydroxyapatite-coated screws: an
Timothy T Davis1, Stephanie Tadlock, Johannes Bernbeck
1*Orthopedic Pain Specialists, Santa Monica, California, U.S.A.; †Alpha Diagnostics, Santa Monica, California, U.S.A.; and ‡Orthopedic Surgery Department, Kaiser Medical Group Los Angeles, California, U.S.A.
Objectives:
To assess if hydroxyapatite (HA)-coated titanium pedicle screws exhibit the same electroconductive characteristics as non-HA-coated screws.
Methods:
Resistance measurements were obtained from a random sampling of 10 HA-coated pedicle screws and 10 non-HA-coated screws, and surgical conditions simulated. Surface resistivity measurements were taken for each screw to determine voltage drop over its entire length.
Results:
The non-HA-coated screws tested showed low resistive properties and proved to be an ideal conductor of electrical current. The resistive properties associated with the HA-coated pedicle screws were found to be similar to those of commonly used insulators removing the effectiveness of triggered electromyographic responses.
Conclusions:
Based on test results, these data suggest that the resistance value of the HA-coated screw is large enough to prevent modern Intra-Operative Monitoring (IOM) equipment from delivering the necessary current through the shank of the screw to create a diagnostic electromyographic response. Any response that would be produced would be because of shunting of electric current from the non-coated head of the screw into adjacent tissue and not through the shank of the screw. These study results suggest that HA-coated screws cannot be stimulated to assist in determining the accuracy of pedicle screw placement.
