gms | German Medical Science

The existing Clip-Piston prosthesis A`Wengen for stapes surgery guarantees the desired safe coupling of the clip only for certain dimensions of the long process of incus. In case of small diameters, there is a loose coupling and consequently a bad sound transfer. In case of very big diameters, the clamping force is too high and a strong force is necessary to slip over the clip on the process of incus. This causes a high risk of damaging the ossicular chain like luxation of incus.

Based on a series of exact measurements of the shape of long process, a new clip was developed which fits optimal even for small and as well for big diameters of incus and guarantees a good sound transfer. On the other hand, the force to slip it on place is reduced by more than 40% leading to an easier application, which is significantly safer for the patient. Moreover, a homogeneous distribution of mechanical stress within the clip was achieved reducing the risk of plastic deformation during application.

The shape of new clip was found using Finite Element simulations and these calculations have been verified by measurements in the lab. A series of prototypes applied on cadaveric temporal bones confirmed the expected firm coupling and reduced application force. First experiences from clinical practice with the new prosthesis approve all expectations concerning the good coupling between clip and incus, an easy handling with an application easier and safer as before.