Proplast and Plastipore.

Sixteen Proplast and 52 Plastipore prostheses, removed at revision surgery, have been examined histologically and the findings illustrated. The macroscopic appearance of the prostheses was preserved. Fibrous tissue capsule formation was common. It has been expected that the prostheses will be invaded by fibrous tissue and thereby stabilized. Fibrous tissue ingrowth was consistently seen in Proplast but not Plastipore prostheses. Multinucleated foreign body giant cells were present in large numbers in both types. There was histological evidence of breakdown of the prostheses.