Demineralized bone matrix as an alternative for mastoid obliteration and posterior canal wall reconstruction: Results in an animal model

Hypothesis: This study was conducted to evaluate the use of Grafton human d emineralized bone matrix as a graft material for mastoid cavity obliteratio n and canal wall reconstruction in an animal model. Background: Canal wall down procedures in the treatment of cholesteatoma ma y result in a problematic mastoid cavity. Elimination of the mastoid cavity by obliteration or canal wall reconstruction can prevent or correct this p roblem. Many techniques and implant materials have been used for this appli cation, yet no single material has proven to be ideal. Methods: Athymic rats received tympanic bulla obliteration and lateral bull a wall reconstruction utilizing the Grafton Putty and Flex formulations, re spectively. Wound healing was monitored twice a week. Auditory brainstem ev oked responses were obtained 8 weeks after implantation. Nine weeks after i mplantation, the animals were killed, and histologic sections were prepared . A histologic bone formation score (range 0-4) was determined for each imp lant. Results: Wound healing occurred without complication. Auditory brainstem re sponse thresholds (average 23.5) fell within the normal range for all ears tested. The average histologic bone formation score for all implants was 3. 7 The average scores for obliteration implants and wall reconstruction impl ants were 3.5 and 3.9, respectively. All wall reconstruction implants under went partial or total collapse into the bulla. Conclusions: The high level of bone formation obtained by the use of Grafto n implants in this study makes this material a promising resource for use i n mastoid obliteration. The use of the material for canal wall reconstructi on will likely require a sturdier preparation to prevent collapse into the mastoid cavity.