Do Internal Orthopedic Screws Interfere with EKG?
No, internal orthopedic fixation screws (spinal, pelvic, or extremity hardware) do not interfere with standard surface electrocardiogram recordings. The ECG signal is generated by electrical activity of the heart and recorded from body surface electrodes, and metallic implants do not produce electrical signals or meaningfully alter the transmission of cardiac electrical potentials to the skin surface.
Why Orthopedic Hardware Does Not Affect EKG
ECG Signal Transmission Principles
The standard 12-lead ECG records potential differences between prescribed sites on the body surface that reflect transmembrane voltages in myocardial cells during depolarization and repolarization 1.
ECG voltage in any lead depends on the projection of the heart vector and is influenced by the geometry of the body and varying electric impedances of tissues in the torso 1.
The signal is attenuated and altered by torso inhomogeneities including thoracic tissue boundaries and variations in impedance, but these are natural biological factors, not metallic implants 1.
Sources of ECG Interference
The American Heart Association identifies specific sources of ECG interference, none of which include internal metallic hardware 1, 2:
- Low-frequency noise: baseline wander, movement, and respiration 1
- High-frequency noise: muscle artifact and power-line or radiated electromagnetic interference 1
- Motion artifacts: electrode and cable movement 2
- Power line interference: inadequate shielding or grounding 2
Distinction from MRI Artifacts
While orthopedic hardware creates significant susceptibility artifacts in MRI imaging that can obscure adjacent soft tissues 3, this is a completely different physical phenomenon related to magnetic field distortion.
ECG recording involves electrical potential measurement at the body surface, not magnetic resonance imaging 1.
The electrical impedance properties of metallic screws do not generate signals or meaningfully alter the passive transmission of cardiac electrical activity to surface electrodes 1.
Clinical Implications
No Special Precautions Needed
Standard ECG electrode placement and recording techniques should be used in patients with orthopedic hardware 2, 4.
Skin preparation (cleaning with alcohol, gentle abrasion) and proper electrode placement remain the key factors for high-quality ECG recordings 2.
The American College of Cardiology recommends using silver-silver chloride electrodes with proper skin preparation to minimize impedance, regardless of internal hardware 2.
Focus on Actual Sources of Interference
When ECG quality is poor in patients with orthopedic hardware, look for the true culprits 2, 4:
- Inadequate skin preparation (impedance >5000 Ω) 2
- Poor electrode contact 2
- Patient movement or muscle tension 2
- Power line interference from inadequate cable shielding 2
- Baseline wander from respiration or electrode movement 1
Electrophysiologic Monitoring Context
The research on pedicle screw placement using triggered electromyography 1, 5, 6 involves direct electrical stimulation of screws to test nerve proximity during surgery—this is fundamentally different from passive ECG recording.
These intraoperative monitoring techniques deliberately apply electrical current to hardware to elicit muscle responses, whereas ECG passively records cardiac electrical activity 1, 5.
Common Pitfall to Avoid
Do not attribute poor ECG quality to the presence of orthopedic hardware. If an ECG is suboptimal in a patient with spinal screws, pelvic fixation, or extremity hardware, systematically address the actual causes: verify proper skin preparation, check electrode contact quality, ensure adequate cable shielding, minimize patient movement, and use appropriate filter settings 2, 4.