An important procedure in ossiculoplasty: autoclaving the ossicles

摘要

Autoclaving of the ossicles prior to ossiculoplasty is a very important procedure in surgery of cholesteatomatous chronic otitis media. Autoclaving allows the reuse of the ossicles removed from patients with cholesteatomatous chronic otitis media as an autograft. It also allows utilization of the malleus, incus and stapes taken from cadavers or of the uneroded malleus and incus removed from patients undergoing non-functional middle ear surgery chosen carefully with detailed history and laboratory analysis. The powerful disinfecting effect of the sterilising procedures of the homografts inactivates prion proteins which cause degenerative encephalopathies. In various studies, it has been concluded that autoclaving does not alter the matrix of the bone which is responsable for its biophysical properties, whereas it removes all viable cells within the bone and denatures the soft tissue attached to the surface of the ossicle. We have also found confirming histological results in our two previous studies published in 1999 and 2001. It is usually recommended that soft tissue on the surface of the ossicles is removed before autoclaving. It is also sufficient to autoclave the ossicles at 134℃, and at 2.5 atmosphere pressure for 5 minutes in a flash autoclave. The autoclaving time of the homograft ossicles must be longer, for 20 minutes. Following the autoclaving, these homograft ossicles should be kept at pH 5.6 for 3 days, then use a solution of 0.5 % formaldehyde at pH 7 and 4℃ for 21 days and it should be washed with physiologic saline solution three times for 7 minutes before use. Depending on the results obtained from our planned comparative experimental study, there will be no need for additional formaldehyde fixation procedure after autoclaving and the autoclaved ossicles will be used immediately without preservation in formaldehyde solution for 24 days.