Electromagnetic Navigation

Electromagnetic navigation is a way of tracking surgical instruments in real time using a magnetic field rather than a camera. This distinction matters most in endoscopic spine surgery. Traditional (optical) navigation relies on cameras that must "see" reflective markers, which needs a clear line of sight — awkward when the surgeon is working down a narrow tube. Electromagnetic navigation has no such requirement: tiny sensors built into the instruments are tracked through a magnetic field, so their exact position is known even when they are deep inside the body or inside an endoscopic working channel. This makes it a natural fit for keyhole and endoscopic techniques.

• People undergoing endoscopic spine surgery, where line-of-sight optical navigation is impractical
• People undergoing percutaneous (through-the-skin) procedures such as screw placement
• Situations where reducing intraoperative X-ray exposure is desirable
• Its use is determined by the surgeon and the procedure

• A control unit generates a low-strength electromagnetic field around the surgical area. Small sensors are attached to the patient and built into the tracked instruments or the endoscope. As the instruments move within the field, the sensors report their precise position back to the navigation computer, which displays them on the patient's scan images in real time. Because tracking does not depend on a camera seeing the instrument, it works seamlessly inside the small channels used in endoscopic surgery — helping the surgeon steer the scope and instruments to exactly the right spot, confirm the working level, and judge how much bone or disc has been removed, all with less need for repeated live X-ray.

• Real-time tracking without needing line of sight — ideal for working inside endoscopic channels
• Reduces the amount of live X-ray (fluoroscopy) needed, lowering radiation to patient and team
• Reported shorter operating and cannula-placement times in endoscopic and percutaneous procedures
• Helps confirm the working level and the extent of decompression during keyhole surgery
• Improves precision in a setting where the target cannot be seen directly at first

• Navigation is an aid that supports, not replaces, the surgeon's judgement and skill
• The magnetic field can in principle be affected by nearby metal instruments, so systems and workflow are designed to manage this
• Set-up and registration must be done carefully; technical issues can require falling back on standard X-ray guidance
• The underlying procedure carries its own risks

• Conventional fluoroscopy (live X-ray) guidance
• Optical (camera-based) navigation, where line of sight allows
• O-arm or intraoperative CT navigation
• Robotic-assisted guidance

Electromagnetic navigation does not change your recovery, which depends on the operation. Its value is in making endoscopic and percutaneous surgery more precise and in reducing radiation exposure during the procedure. Your surgeon will explain how it supports your specific operation.

• —Royal College of Radiologists — iRefer: Making the Best Use of Clinical Radiology
• —British Association of Spine Surgeons (BASS)
• —UK Health Security Agency — Ionising Radiation: Patient Dose Information

This information is for general patient education and is not a substitute for an individual consultation. Always seek personalised advice from a qualified spinal specialist.