Homograft tympanic membrane in cats.

Abstract

AbstractA total of 91 cats were evaluated to determine the effectiveness and nature of closure of total tympanic membrane perforations with homografts preserved in buffered formaldehyde, 70 percent alcohol, benzalkonium in Tis‐U‐Sol (1:750 solution), or Cialit (1:5,000 aqueous solution). Controls consisted of unoperated ears, ears with partial and total perforations that were not grafted, ears in which the total tympanic membrane was removed and immediately replaced, and ears grafted with fresh homograft tympanic membranes.The study revealed that the removal of the tympanic annulus was necessary to prevent spontaneous regrowth of a new tympanic membrane. The percentage of successful closures of tympanic membrane perforations according to the preservative was formaldehyde 50 percent, alcohol 50 percent, benzalkonium 45 percent, and Cialit 30 percent. The rate of successful closures with fresh autograft tympanic membranes was 40 percent and with fresh homografts 25 percent. The homografts preserved in formaldehyde or alcohol were more rigid and easier to handle than were those preserved in benzalkonium or Cialit.The histologic findings were similar in ears that had developed a new tympanic membrane after grafting with preserved homograft tympanic membranes and in ears with fresh homografts or autografts. The graft served as an inert scaffold for the new tympanic membrane to grow across. Gelfoam used in the middle ear to support either a homograft or an autograft became incorporated into the new tympanic membrane and was associated with a foreign‐body reaction. There was, however, no evidence of an immunologic reaction to the homograft.