Damaged ossicles
Serious ear infections and head injuries can damage the ossicles (tiny bones) in the middle ear that pass sound waves from the eardrum to the inner ear, causing hearing loss. Occasionally, babies are born with misshapen ossicles.
Treatment
A surgical operation is sometimes offered to fix or replace damaged ossicles. How much your hearing will improve after surgery depends on the cause and how severe the damage has been to the ossicles and middle ear.