Final answer:
The procedure where the stapes is replaced with a prosthesis is called a stapedectomy, and it is typically done to improve hearing when the stapes bone is affected.
Step-by-step explanation:
When the stapes is permanently removed and replaced with a prosthesis, the procedure is called a stapedectomy. This surgical procedure is undertaken when there is a problem with a patient's hearing due to the immobility or malfunction of the stapes bone in the middle ear. Replacing the stapes with a prosthesis can restore or improve hearing in cases of otosclerosis, which is a common cause of hearing loss when abnormal bone growth immobilizes the stapes.