Surgical pathology of middle ear implants.

During the past 15 years a series of 25 middle ear implants was removed at the time of revision surgery and prepared for histological study. These revision operations were performed because of failure to control the disease and/or persistent or recurring hearing loss. The ossicular and cortical bone autografts showed similar behavior in that they underwent creeping substitution with vitalized bone in amounts varying from 0% to 83%. There was no correlation to duration of implantation. The four cartilage grafts, on macroscopic evaluation, showed a loss of rigidity. Two of three cartilage autografts showed a high rate of survival of chondrocytes. The two TORP prostheses showed extensive invasion of their porous spaces with foreign body giant cells. One of the latter, implanted for over four years showed fibrous replacement of plastic material. The two polyethylene tubes showed intraluminal foreign body reaction and new bone formation.