Technology continues to improve and expand what doctors can do. A new laser-scanning microscope can tell if a patient’s hip replacement is infected. The time to get results is only about 30 minutes.
Hip infection is the second most likely cause of implant failure. Hospitals can’t afford to go without this new tool. It costs $50,000 to replace an infected artificial hip joint. The cost of the laser-scanning microscope is around $350,000. That seems high, but each year in the United States thousands of aging adults need joint replacements. The hospital would get back what it spent if only seven patients are saved from a failed revision surgery.
There are several ways to test for infection. One is to pass a cotton swab across the infected area. The second is to take samples of tissue from around the implant. In both methods, samples are then tested for bacteria and other organisms. This is called a tissue culture. A more thorough search for infective agents involves culturing the implant itself. The surface of the cup, the cement surfaces, and the stem are scraped. The scrapings are then cultured.
The hospital cultures must be held in the lab for up to seven days to detect many of the infectious agents. Even then not all the bacteria actually present shows up. In comparison, the laser-scanning microscope scans the implant and gives results within 30 minutes. It’s fast and doesn’t allow the samples to dry out. It also shows when there are multiple strains or subtypes of bacteria present.
In this study, researchers compared the results of tissue cultures from tissue samples and those taken from the actual implant. They used the standard hospital procedure and compared it to the newest method using the laser-scanning microscope. The authors point out that early detection of all the possible infectious agents is a big step toward reducing failure of hip revisions. It’s likely the new implant will get infected too if all the bugs aren’t gone before the new implant is put in.
On the basis of this study, it is suggested that tissue cultured from failed hip implants include scrapings from the original joint replacement. A laser scanning microscope will show the results quickly and accurately.