Long-term fate of Plastipore in the middle ear.

Four Plastipore prostheses, removed at revision surgery 7-10 years after implantation, have been examined. The gross appearance of the prostheses was preserved. The prostheses were surrounded by a fibrous tissue capsule and showed fibrous tissue ingrowth localized in peripheral zones. Foreign-body giant cells and macrophages were detected in small numbers. Histologic evidence of breakdown of the prostheses, in the form of microdisintegration of the walls of micropores, was detected on a small scale. Compared to the massive foreign-body reactions reported in short-term studies, the tissue reaction apparently subsides with time and becomes insignificant. Strict criteria for insertion should be regarded.