Intelligent knee implants can soon be a reality thanks to the research carried out by a team that includes professors at the University of Binghamton, at the State University of New York.
Knee replacement surgery is the most frequent joint replacement procedure, with the number of surgeries increasing every year. Many of these surgeries are performed to replace an older implant or one that has been worn out. Increasingly, this surgery is being carried out for younger and more active patients who are facing a dilemma. When subjected to surgery, it expects them to remain physically active for their overall health, but this activity can also be worn out of the new implant. Often doctors do not know if patients are overexpressing until they begin to develop symptoms. At this point, the implant damage has already been done. For a young patient, going through the knee replacement surgery every five or ten years is a daunting task, but finding a perfect balance of activity levels to maintain the integrity of the implant has been equally discouraging. .
The researchers decided it was time to create smarter knee implants that could control changes in activity as they happened. Assistant professor Sherry Towfighian of the University of Binghamton was the main principal researcher of the study, which has been supported by the National Institutes of Health (NIH).
"We are working on a knee implant that has integrated sensors that can control the pressure on the implant so that doctors can have a clearer understanding of the amount of activity that negatively affects the implant," said Towfighian .
Sensors allow doctors to inform patients when a given movement has become implanted so that patients can adjust quickly and avoid further implant damage. It helps them find the sweet spot for each individual patient.
While the sensors solved a problem, they brought another one. The researchers did not want to feed the sensors with a battery that could have to be replaced periodically and, therefore, to defeat the intention of a smart implant. Instead of this, they worked on an energy-saving mechanism that can promote the knee movement. Wathiq Ibrahim, a postdoctoral group in the Towfighian group, developed a prototype of the energy harvester and proved that, under a mechanical testing machine, it examined its production under equivalent body loads.
They used triboelectric energy, a type of energy that is collected from friction. Once someone walks, you can use the friction of the microfires that come in contact with each other to feed the load sensors.
Associate professor Emre Salman of the University of Stony Brook designed the circuit and determined that he would need 4.6 microwaves. Preliminary tests showed that the average person's walk will produce six microlats of power, more than enough to feed the sensors. This part of the research was complemented by the assistance of Assistant Professor Ryan Willing of the University of Western Ontario, who worked on implant design and on the sensor package.
These smart implants will not only give feedback to doctors but will help researchers in the development of future implants. "The sensors will tell us more about the demands that are placed on the implants and, with this knowledge, the researchers can begin to improve the implants even more," said Towfighian.
Towfighian hopes that the combination of activity sensors and a self-propelled system will increase the life of the knee implants and reduce the need for follow-up surgeries. For young patients who consider the possibility of knee replacement surgery, this development can change their lives.