Ossiculoplasty is the surgical restoration of the sound transmitting mechanism of the middle ear. The ossicles (malleus, incus, and stapes) are three bones in the middle ear that assist in the mechanical transduction of sound energy. The sound energy is collected by the tympanic membrane, transmitted across the middle ear along with the three middle ear bones and into the fluid-filled cochlea. Collectively, the middle ear bones are known as the ossicular chain. There are three types of synthetic ossicular prostheses: partial ossicular replacement prosthesis (PORP), total ossicular replacement prosthesis (TORP), and incus interpositional or incus replacement prosthesis.
Why is an ossiculoplasty performed?
It is usually performed in patients who have a problem with their ossicular chain that is causing a hearing loss, usually a conductive hearing loss. People may develop an ossicular chain problem for several reasons including:
- Trauma – this is most commonly seen in road traffic accidents when the temporal bone of the skull (the part of the skull that houses structures of the ear) is fractured. During such an injury, the ossicles may become dislocated. Barotrauma (trauma due to pressure changes) or acoustic trauma (trauma due to very loud noises) may also cause ossicular disruption.
- Infection – chronic infection within the middle ear may cause erosion of one or more of the ossicles over time. The most common place for erosion to occur is at the point where the incus (anvil) meets the stapes (stirrup).
- Cholesteatoma – this is a skin cyst that develops due to an abnormal migration of dead skin into the middle ear. The cholesteatoma may result in recurrent infections that can cause erosion or may itself directly erode the ossicles.
- Immobility – occasionally people are born with ossicles that do not move properly due to abnormal connections between the bones.