Better Test for Bionic Joint Infections
Reported August 16, 2007
(Ivanhoe Newswire) — An undetected infection around a prosthetic joint can mean more surgery for patients who have already gone through the process of replacing a knee, shoulder or hip. Now, scientists have a better way to test for microscopic germs living on patients’ replacement parts.
Mayo Clinic researchers in Rochester, Minn., have discovered a new, more accurate way to detect infections in prosthetic joints. The new test samples bacteria sticking to the actual prosthetic surface. Conventional screenings only sample the surrounding tissue. Researchers report the new method could lead to better treatments and healthier joints for patients.
Researchers studied 331 patients with prosthetic hip or knee joints who were having them removed for infection or other reasons. The new test detected 78.5 percent of infections compared to the conventional screening, which detected 60.8 percent.
“The problem with the conventional method is that you need multiple tissue specimens, because the sensitivity of a single specimen is not good. In other words, the infection might be missed with just one sample,” lead author Robin Patel, M.D., was quoted as saying.
During the new test, surgeons remove a prosthetic joint, as they normally would, place it in a container, and send it to the lab. A solution is then added to the container, which is shaken and exposed to ultrasonic waves to remove bacteria growing on the surface.
Researchers were able to identify a wide variety of bacteria causing prosthetic joint infections. The new knowledge will allow doctors to give patients the correct treatment for their specific infection.
Dr. Patel reported patients with prosthetic joints may not even know they have an infection. Often, pain is the only symptom.
About 750,000 total hip and knee replacement surgeries are performed in the United States every year. According to the American Academy of Orthopedic Surgeons, this number is expected to increase to 2.5 million by 2030.
SOURCE: The New England Journal of Medicine, 2007;357:654-63