Introduction Active and passive prostheses for hearing rehabilitation are anchored to the anatomical structures in the middle ear using various methods. Such coupling must be able to resist dislocation due to atmospheric pressure fluctuations and forces caused by the implant's own movements in the case of active components. Furthermore, there is the possibility of a dislocation due to an accident-related external force acting on the skull.
Material and methods In this study a method is presented to experimentally quantify the risk of prosthesis dislocation due to the application of force to the skull. This is realised by means of drop tests in a calibrated test rig. A frame made of item profiles was fitted with a vertically movable, rail-mounted carriage. A temporal bone including the implant to be examined and acceleration sensors were firmly attached to the carriage. The drop test was then carried out with different spatial orientations of the temporal bone. Using the sensors, the severity of the simulated accident was compared to the Head Injury Criterion (HIC) from automotive crash tests.
Results HIC values of up to 1'000 were be achieved with the test rig. This corresponds to a severe concussion or the Euro-NCAP classification "red". The method was tested on a sensor in the incudostapedial joint as an example. A photographic before/after comparison and a functional test did not reveal any dislocation.
Discussion The method can be applied to any other prosthesis in the middle ear. The necessity of such an experiment depends on the quality of the coupling and the weight of the prosthesis itself.
Poster-PDF
A-1404.pdf
