The lessons of middle-ear function in non-mammals: improving columellar prostheses.

Due to the simplicity of their manufacture and placement, middle-ear prostheses are generally constructed using only a single 'ossicle'. The variety of pathologies frequently make it necessary to devise individual solutions and the results are often unsatisfactory. Many methods of improving the prostheses have been tried, with very mixed results. Even until recently, the fundamental assumptions underlying the use of single-ossicle, or columellar, prosthesis have been questioned, with suggestions that this type of prosthesis should be abandoned in favour of attempts to reconstruct a true three-ossicle middle ear. As some of the assumptions in the literature regarding columellar middle ears are incorrect and some published information is not easily accessible, a brief review of pertinent details of non-mammalian systems is given here.