Ability to Adjust in Length and Damping: Missing Features in Middle Ear Implants?

Dominating part of the middle ear is the ossicular chain, a pin-jointed assembly of three bones (malleus, incus and stapes). If destroyed by disease or deteriorated by aging, it is fully or partially replaced by an alloplastic implant. A major issue for these devices is the possibility to adapt the implant in length during operation to cope anatomical variations. Several ideas to implement this feature are claimed in patents. Further, two major functionalities provided by the native ossicular chain are rather difficult to implement. This is the ability to adapt in length in-situ to compensate lateral displacement of the eardrum and a damping function to protect the inner ear at exceeding sound pressure levels. Some interesting approaches to implement these functionalities are protected by patents. A brief overview does depict current developments and may give inspiration to find new approaches to fuel the evolution of middle ear implants.