The anterior tympanomeatal angle: the aetiology, surgery and avoidance of blunting and annular cholesteatoma.

Forty-eight cases of anterior annular cholesteatoma were treated surgically. All these cholesteatomas had occurred following surgical repair of the tympanic membrane by the onlay method. To confirm the likely aetiological causes, 49 specimens of the anterior annular sulcus were studied histologically. It was found that in 31% of specimens there was a fold of epithelium penetrating deep into the subepithelial tissue. In 6 specimens there were epithelial cones present and in 9 specimens excessive subepithelial fibrous tissue was noted. The complication of "blunting" caused by the onlay technique is almost impossible to avoid. A more dangerous complication is annular cholesteatoma. The surgery of blunting and annular cholesteatoma and the principles of the underlay method of grafting are described.