Artificial hip joints make life easier for many people. A new generation of implants should be able to do even more: Rostock researchers are working on a prosthesis that is equipped with sensors and circuits. The goal: the joint should think for itself.
Artificial joints last longer and longer, but not forever. In the future, younger patients in particular will have to undergo repeated operations to replace worn joint prostheses. The fact that an artificial hip doesn’t last forever is due to wear and tear on the one hand, and overuse on the other, says Daniel Klüß, who heads the Innoproof test laboratory in Rostock. Can overuse be overcome? “Clear yes,” said Klüß.
Electrically active implants are being developed for this purpose at the University of Rostock. Among other things, the researchers want to find out how electrical voltage can be generated from mechanical energy generated when running or walking. This is the most important prerequisite for accommodating intelligence in the hip joint of the future, explains Klüß.
For this purpose, the hip prosthesis is equipped with a so-called piezo ceramic. “In the laboratory test, the mechanical energy of the deformation of the ceramic material used is converted into electrical energy.” The deformation of the ceramic occurs, for example, when a patient regularly loads his implant while walking. “The resulting electrical energy is collected, in technical jargon we speak of energy harvesting, in order to supply sensors and electrical circuits in the implant with it,” says Klüß.
The sensors and circuits in the intelligent hip implant should later enable completely new functions. The researchers aim, for example, for the artificial hip to measure the quality of the surrounding bone and how firmly the implant is still anchored in the bone.
The newly developed diagnostic system should also be able to provide information about how active the patient actually is. Because: The more active the patient, the more electrical voltage is generated. By reading the sensor, doctors can later see whether, for example, exercises during rehabilitation have been completed conscientiously or whether the patient has overloaded his implant with his daily jog in the park or, conversely, has taken it easy on the couch at home, explains Klüß.
But the intelligent joint offers even more potential: “We want to use the electrical energy to stimulate bone growth.” This is particularly important for patients who have already had their second or third hip operation.