Implantable hearing aids are gaining importance for the treatment of sensorineural hearing loss and also for mixed hearing loss. The various hearing aid systems, combined with different middle ear situations, give rise to a wide range of different reconstructions. This article attempts to summarize the current knowledge concerning the mechanical interaction between active middle ear implants (AMEls) and the normal or reconstructed middle ear. Some basic characteristics of the different AMEls are provided in conjunction with the middle ear mechanics. The interaction of AMEls and middle ear and the influence of various boundary conditions are discussed in more detail.