A thermal image showing that the alternating magnetic fields selectively heating the metal knee joint.
Scientists at UT Southwestern Medical Center have developed a new technique using high-frequency alternating magnetic fields to heat artificial joints in the body and destroy bacterial films on their surfaces.
Bacterial infections on artificial joints used in knee and hip replacements are a common and serious complication. The bacteria tend to form slimy films on the metal surfaces of the joints called biofilms, and they are difficult to treat using antibiotics.
Dr. David Greenberg, of UT Southwestern Medical Center, describes the solution the researchers developed. “We were looking for better ways to target and treat biofilms,” he says. 
“Our idea was to put a coil around the joint and run a current through it to create alternating magnetic fields. Human tissue isn’t conductive but metal is, so only the implant would heat up.” The principle is the same as that in induction cooktops, which use magnetic fields to heat metal pots for cooking.
The scientists hoped that they could generate enough heat on the metal surfaces to kill any bacteria while avoiding damage to nearby tissue. First, they tested the system on metal joints in the lab and found that they could generate enough heat to kill bacteria.
Then they used the system in mice to show that a short-duration, high-power burst of the magnetic field minimized damage to nearby tissue. This approach meant that they could rapidly achieve a high temperature on the metal surface of an implant before there was time for the heat to build up in the surrounding tissues. The team have now planned more safety tests to see if the system could be used in human patients.
Here’s a video from UT Southwestern Medical Center about the research:
Study in Scientific Reports: Employing high-frequency alternating magnetic fields for the non-invasive treatment of prosthetic joint infections…
