Abstract
The technical details of 1 550 stapedectomy operations for otosclerosis are discussed. The operation is based on the technique described by Shea using a Teflon piston for reconstruction. Emphasis is laid on the extreme care and precision in making a calibrated trepanation hole as well as on the trimming and the positioning of the Teflon prosthesis. The concave perilymph meniscus protects the labyrinth from the penetration of foreign particles. The fact that only the vestibular endothelium builds up the effective obturating membrane, constitutes another fundamental aspect. The shape of this membrane is greatly defined by the contact angle of the perilymph on the prosthesis.