The motion of conventional and novel total ossicular replacement prostheses during changes in static pressure

Abstract

To investigate the motion of prostheses used to reconstruct ears with an absent stapes arch. We have studied the motion of conventional total ossicular replacement prostheses (TORPs) and a novel incus-stapes replica prosthesis (ISRP), which connects the malleus head to the footplate, during changes in middle ear pressure (+400 to -400 dPa) in fresh human temporal bones using digital video clips and photographs. The pressure in the (sealed) external auditory meatus was varied using a manual tympanometer. The displacements of the prostheses in the medial to lateral plane have been measured using the dimensioning tool of Corel Draw. During changes in static pressure, TORPs move more in the lateral to medial plane than ISRPs. The motion of ISRPs is similar to that of the intact ossicular chain. The ISRP design is less likely to damage the cochlea during changes in static pressure than a conventional TORP, but the maximum medial displacement of the TORPs studied was less than 0.1 mm.