Ossicular chain is the small bones of the middle ear which are articulated to form a chain for the transmission of sound from the tympanic membrane to the oval window. In its early stages, cholesteatoma tends to attack the ossicles, the small bones conducting sound from the eardrum to the inner ear. Due to the erosion of the ossicles, there is a discontinuity of the ossicular chain and sound waves cannot transmit to the inner ear, as a result, hearing loss develops.
Ossiculoplasty is defined as the reconstruction of the ossicular chain. The ideal prosthesis for ossicular reconstruction should be biocompatible, stable, safe, easily insertable, and capable of yielding optimal sound transmission. The most commonly used autograft material has been the incus body, which is often reshaped to fit between the manubrium of the malleus and the stapes capitulum. Alloplastic materials can also be used for ossicular reconstruction today. Alloplastic materials can be classified as biocompatible, bioinert, or bioactive such as polyethylene tubing, Teflon, and Proplast are used.
Conductive hearing loss from ossicular chain abnormalities may result from either discontinuity or fixation of the ossicular chain. In order of frequency, discontinuity most commonly occurs because of an eroded incudostapedial joint (occurring in approximately 80% of patients with ossicular discontinuity), an absent incus, or an absent incus and stapes superstructure. Ossicular fixation, exclusive of otosclerosis, most commonly occurs from malleus head ankylosis or from ossicular tympanosclerosis.
The status of the ossicular remnants determines which implant can be used. In general, better hearing results are achieved when as much of the remaining functional ossicular chain as possible is used during reconstruction.
A PORP (partial ossicular replacement prosthesis) is the best option for ossicular reconstruction when the malleus and incus are absent in the presence of an intact stapes.
A TORP (total ossicular replacement prosthesis) is the best option for reconstruction when the only footplate is present.
