Many patients suffering from arthrosis or other kinds of damage in the hip joint need an endoprosthesis at some point. However, this prosthesis can loosen again after some time, so that it must be replaced. A patient can only receive a prosthesis in the same joint twice in his life because part of the bone needs to be removed during implantation. In order to delay this replacement surgery for as long as possible, the TH Mittelhessen University of Applied Sciences develops a new diagnostic method: It is supposed to detect ultrasonic sounds that indicate the loosening of a prosthesis.