S. Nishihara et Rl. Goode, EXPERIMENTAL-STUDY OF THE ACOUSTIC PROPERTIES OF INCUS REPLACEMENT PROSTHESES IN A HUMAN TEMPORAL BONE MODEL, The American journal of otology, 15(4), 1994, pp. 485-494
Many middle ear prostheses are available for reconstruction of a missi
ng or damaged incus. Little is known of the relative acoustic performa
nce of these prostheses in vitro and the parameters (mass, shape, tens
ion, angulation, area of head) that modify this performance. This repo
rt describes experiments in a human temporal bone model comparing the
effect on stapes displacement of six commercially available incus repl
acement prostheses (IRP). Measurements were performed using a laser Do
ppler vibrometer before and after incus removal and IRP placement betw
een the tympanic membrane (TM) and stapes head. In addition, experimen
ts were performed on the effect of increasing prosthesis mass, varying
the tension between TM and stapes head, changing the surface area in
contact with the TM, and comparing different TM contact sites. All pro
stheses tested showed reasonable acoustic performance compared to the
baseline condition. Optimum tension between the TM and stapes head pro
duced the best overall sound transmission. The mid-malleus and umbo lo
cations were the best malleus contact sites; however, the posterior TM
contact site also worked well. Increased mass improved low frequency
transmission and impaired higher frequency transmission, whereas a lar
ger contact area with the TM contributed to increased gain in the mid
frequencies.