Tissue reaction to middle ear prostheses: in vivo observation (rabbit ear lobe) of polyethylene tube, stainless steel wire and absorbable gelatin sponge used in middle ear surgery.

Over the past ten years, polyethylene tube, stainless steel wire and absorbable gelatin sponge have come to be used in middle ear surgery. A modified Williams' steel chamber with a transparent central area was embedded in a rabbit ear lobe surgically, and cross-sectioned polyethylene tube, stainless steel wire or absorbable gelatin sponge were inserted respectively. The in vivo tissue reaction to each of these installed materials was observed daily microscopically. Finally, in the case of both the cross-sectioned polyethylene tube and the stainless steel wire, the chambers were fixed with 10% formalin solution and the contents stained for histological study. The results were as follows: Absorbable gelatin sponge was absorbed completely by phagocytosis in 62 days. Polyethylene tube was encapsulated by a layer of fibroblasts by day 110 in one case and by day 140 in another case; these findings were confirmed histologically on day 110 and 281. Almost all the surface of the stainless steel wire was encapsulated by a layer consisting of giant cells, on which a dense fibrous layer was superimposed by day 82. It is concluded that polyethylene tube, stainless steel wire, and absorbable gelatin sponge should be well tolerated in middle ear surgery.