Can triggered electromyography be used to evaluate pedicle screw placement in hydroxyapatite-coated screws: An electrical examination

Timothy T. Davis, Stephanie Tadlock, Johannes Bernbeck, Daniel A. Fung, Diana M. Molinares

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)138-142
Number of pages5
JournalJournal of Clinical Neurophysiology
Volume31
Issue number2
DOIs
StatePublished - Apr 2014
Externally publishedYes

Keywords

  • Electromyography
  • EMG
  • Hydroxyapatite
  • Lumbar spine surgery
  • Pedicle screw

ASJC Scopus subject areas

  • Physiology
  • Neurology
  • Clinical Neurology
  • Physiology (medical)

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