Smart knee implants may be a possible alternative to surgery thanks to researchers at Binghamton University and State University of New York.
Knee replacement surgery is a common procedure and continues to increase each year. Many of those surgeries are often done to replace an older implant or one that has been worn out. Often, this means patients are expected to stay active after they undergo their surgery, but this activity can cause wear and tear on the implant. Most times, doctors don’t know if the patient is overexerting their implant to strenuous exercise regimes until symptoms develop. By this point, the implant has most likely already undergone damage. For a young patient, having knee replacement surgery every five or 10 years isn’t something you readily want to go through, and finding the perfect amount of exercise can be seemingly daunting.
In response to this dilemma, researchers decided it was time to create a smart knee implant that could monitor changes in activity in real time.
“We are working on a knee implant that has built-in sensors that can monitor how much pressure is being put on the implant so doctors can have a clearer understanding of how much activity is negatively affecting the implant,” said Assistant Professor Sherry Towfighian from Binghamton University, lead investigator on the study.
The sensors on the knee implant would allow doctors to tell patients when a specific movement is too much for the implant to handle. This way, patients can quickly adjust their physical movements in order to mitigate the destruction of their implant. It could also help doctors identify a specific exercise routine for each individual and cater to their needs.
Although the sensors solved the problem of wear and tear on the implant, it did bring in another problem. Researchers did not want to power the sensors with a battery that needed to be replaced periodically. This would be contrary to the purpose of the smart implant. So, the researchers worked on an energy harvesting mechanism that could power the knee implant from motion. Wathiq Ibrahim, a postdoc in Towfighian’s research group, developed a prototype of the energy harvester, which was tested under a mechanical machine to examine its output under equivalent body loads.
The researchers used triboelectric energy to power the smart implant, an energy that is collected from friction. Therefore, when someone walked, the friction would power the load sensors.
Additionally, associate professor Emre Salman from Stony Brook University designed the circuit and determined it would need 4.6 microwatts. Their research showed that an average person’s walk produced six microwatts of power, which was more than enough to power the sensors.
The researchers hope that these smart implants will both provide doctors with reliable feedback and influence the design of future implants.
“The sensors will tell us more about the demands that are placed on implants, and with that knowledge, researchers can start to improve the implants even more,” Towfighian said.
