Manipulating the mobile stapes during tympanoplasty: the risk of stapedial luxation.

Manipulating the mobile stapes is a central procedure during tympanoplasty, i.e., mounting a prosthesis onto the stapedial head or dissecting cholesteatoma matrix off the oval window niche. An excessive displacement of the stapedial suprastructure as caused by these manipulations with hand-held instruments might result in a rupture of the annular ligament. Bacteria invading through this perilymphatic fistula threaten the inner ear. In experiments with temporal bones, the author investigated the rupture mechanisms of the annular ligament with definite stapedial manipulations. Leaks, which became detectable by exerting pressure on the inner ear fluid, occur only when all suspension fibers are completely ruptured. Further clinical aspects with different directions of stapedial manipulations are demonstrated.