Comparisons of the mechanics of partial and total ossicular replacement prostheses with cartilage in a cadaveric temporal bone preparation

Conclusions: Reconstruction of the ossicular chain differentially affects the motion of the tympanic membrane (TM) and the stapes.

Objectives: To determine the effect of different ossicular replacement procedures on the sound-induced motion of the TM and stapes.

Methods: A combination of digital stroboscopic holography and laser Doppler vibrometry was used to determine the sound-induced motion of the TM and stapes in cadaveric temporal bones in which the ossicular chain was reconstructed using 12 varied standard techniques. The variations included the use of total or partial ossicular prosthesis, size of cartilage interposed between the TM and the prosthesis, and the length or fit of the prosthesis between the TM and stapes. The measurements were carried out in repeated measures format, so that each manipulation was performed in each temporal bone.

Results: The volume displacement of the TM was in general reduced by reconstruction, with the largest reductions occurring with high-frequency stimulation in the reconstructions with a 'large' cartilage oval interposed between the TM and the prosthesis. Larger stapes motions in response to low-frequency sound were observed with either 'loose' or 'best' fit TORP with a 'small' cartilage plate between the TM and the prosthesis.