Laser doppler vibrometry data of the Clip piston MVP

Arnold A., Stieger CH., Häusler R.

Published: MEMRO 2006, 4th International Symposium on Middle Ear
Mechanics in Research and Otology: Selected Abstracts

Background: A new malleus handle prosthesis for malleo-vestibulopexy
and revision stapedotomy has been developed at our departement and successfully
used during the last five years. The piston prosthesis bears the
CliP®-mechanism to facilitate attachment to the malleus handle and length
and position can easily be adjusted intraoperatively with a movable hinge.

Objective: The study was devised to determine if the special developed
hinge of the CliP Piston MVP causes a loss of sound transfer from the malleus
grip to the vestibulum.

Methods: A middle ear model was set up, consisting of a vibrator normally
used in an active implantable hearing device with a metal arm in shape and
dimension of an actual malleus handle, where the CliP Piston MVP was attached
with the hinge bend to an angle of about 120°. The piston end of the
prosthesis dipped in a hole of a plastic container filled with water simulating
a piston hole in the footplate. The excitation level corresponded to more than
110 dB SPL for frequencies between 100 Hz – 10000 Hz. With a laser doppler
vibrometer the movements were picked up at different spots in the area
of the clip, the hinge and the piston.

Results: The overall characteristics of the transferfunction was practically
identical (difference < 3dB). Additionally biphasic resonance peaks
(5-10 dB) were observed around 1000 Hz. Discussion: Our results show
very stable transfer properties over the frequency band. The noticed resonance
peaks of 5-10 dB are very probably below significance level in
clinical pure tone audiometry. This is in accordance with our experience
from clinical practice.

Conclusion: The CliP Piston MVP provides good transfer characteristics
from the malleus handle to the vestibulum.