Tympanoplasty with mastoid obliteration using hydroxyapatite granules for aural cholestatoma. A clinical and experimental study.

Hydroxyapatite granules were employed for mastoid obliteration in cases of aural cholesteatoma. After eradicating a cholesteatoma by the canal-down technique, the canal wall was reconstructed with cortical bone chips, and the mastoid cavity was obliterated with hydroxyapatite granules. Tympanoplasty by this technique was performed on 48 ears with aural cholesteatoma. There was no recurrence of cholesteatoma during the follow-up period of two years after surgery. One case of residual cholesteatoma was found in the mesotympanum. There were two cases in which the hydroxyapatite granules became exposed through the posterior canal skin. An air-bone gap of less than 20 dB was achieved in 73% of all the patients. Experimental studies in guinea pigs have demonstrated that hydroxyapatite granules do not undergo morphological changes in and are tightly interdigitated with newly formed bone tissue growing from bulla bone one year after hydroxyapatite implantation in the temporal bullae. The newly-formed bone showed incomplete osteon structures. Excellent biocompatibility and bone adaptability of hydroxyapatite granules were demonstrated experimentally. It is concluded that tympanoplasty with mastoid obliteration using hydroxyapatite is safe and useful for avoiding mastoid cavity problems and for preventing the recurrence of cholesteatoma.