A scanning electron microscopic study of crimping of stapedial prostheses.

Objective: The aim of this study was to evaluate, through the Scanning Electron Microscopy, the loop closure of four types of stapedial prostheses and to compare the different systems of crimping to the long process of the incus.
Materials and Methods: Four types of stapedial prostheses (one platinum-teflon, two different titanium and one nitinol-teflon pistons) were inserted in 40 specially prepared temporal bones simulating the in vivo stapedotomy procedure. Two pistons were crimped by single manual manoeuvre with a McGee microforceps; the remainders were self-retained and thermal-crimped, respectively. All the specimens were evaluated through the Operative Microscopy and the Scanning Electron Microscopy.
Results: Through the Operative Microscopy, all prostheses apparently achieved a correct adhesion to the long process of the incus; on the contrary the Scanning Electron Microscopy study demonstrated some limits of the manual crimping and the different coupling with the ossicular chain of each type of stapedial prosthesis.
Conclusion: A complete adhesion of the prosthetic loop cannot be obtained because of the irregular profile of the incus at the site of attachment of the stapedial prosthesis. Consequently, on the basis of the morphological analysis with Scanning Electron Microscopy, in the surgical practice, the preference could be given to the stapedial prostheses that achieve greater contact such as the self-retaining and thermal crimping pistons compared to the standard sized prostheses considered.
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