Design and manufacturing concept of a postoperative adjustable prosthesis for ossicular chain reconstructions

The tympanoplasty-III is a widely used method to heal the conductive hearing loss with passive prostheses. One of the major challenges during this procedure is to determine the correct prosthesis length during the surgery, in order to apply an optimal tension on the tissues. However, a suboptimal tension on the tissues may occur because of a varying ambient pressure and tissue changes after the operation. This may decrease the quality of sound conduction, cause prosthesis luxation and even injure the tympanic membrane or inner ear. Yet, the state of the art prostheses can only be adjusted during the operation and they cannot adapt themselves to these postoperative changes. In this paper, we present a manufacturing concept for a new middle ear prosthesis that can adapt its length to postoperative changes. Our work on the manufacturing process includes an early concept evaluation with a finite element model as well as our first outcomes with the manufactured prosthesis models.