Which procedure is performed to remove diseased or damaged mastoid cells while preserving the ossicular chain?

The procedure performed to remove diseased or damaged mastoid cells while preserving the ossicular chain is best described by mastoidectomy. This surgical technique specifically entails removing infected or pathological tissue from the mastoid cavity, which is located just behind the ear. A key aspect of this surgery is that it is typically structured to retain the integrity of the ossicular chain—the series of tiny bones in the middle ear that are essential for hearing.

In contrast, a radical mastoidectomy usually involves more extensive removal of both the mastoid air cells and the ossicular chain, which often results in the loss of hearing function in that ear. A stapedectomy is a distinct procedure targeting the stapes bone in the middle ear, typically performed to improve hearing in cases of otosclerosis. Fenestration, on the other hand, is related to creating a new opening in the inner ear, often not associated with mastoid surgery directly.

Thus, mastoidectomy focuses on cleaning the mastoid area while prioritizing the preservation of hearing by keeping the ossicular chain unharmed. This makes it the correct choice for the described procedure.