Histology of extruded Plasti-Pore ossicular prostheses.

Twenty-three Plasti-Pore ossicular prostheses removed from the human middle ear following partial or total extrusion were investigated by light microscopy. No specific tissue reaction other than the ingrowth of histiocytic cells elicited from the porous Plasti-Pore was found. The only histologic feature typical of extruded prostheses was the presence of granulocytes in all parts extruded. In our opinion this finding was the inflammatory reaction following the ischemic necrosis of tissue grown inside the pores and the superimposed bacterial colonization. We concluded that no histologic feature supports a biologic cause of extrusion, and that extrusion instead is related to biofunctional characteristics.