Histologic Evaluation of Micronized AlloDerm After Injection Laryngoplasty in a Rabbit Model.

Objectives/hypothesis: Micronized AlloDerm is a commonly used injectable material for injection laryngoplasty; however, the histologic response to laryngeal implantation and resorption rate over time have not been elucidated. This study aimed to evaluate the in vivo response of micronized AlloDerm over time after laryngeal implantation using a rabbit model.

Study Design: Animal model.

Methods: The left recurrent laryngeal nerve was sectioned in five New Zealand White rabbits to create a vocal cord paralysis. Two weeks later, injection laryngoplasty was performed with 100 μL of micronized AlloDerm. Animals were sacrificed 4 (two rabbits) and 12 (three rabbits) weeks after injection. Histologic sections were stained and evaluated by a single pathologist. Volume estimates were made by assuming the implant took an ellipsoid shape using dimensions calculated from histologic slides.

Results: In all cases, histological analysis revealed a lymphocytic inflammatory response infiltrating the peripheral margins of injection. After 4 weeks, the volume of injected material remaining in two rabbits was 404 and 278 mm (average 341 mm ). After 12 weeks, the volume of injected material remaining in three rabbits was 0, 61, and 124 mm (average 62 mm ), an 82% difference in volume of material between animals sacrificed at 4 weeks versus 12 weeks.

Conclusions: Injection laryngoplasty using micronized AlloDerm induces a lymphocytic inflammatory response after injection in a rabbit model. Though a significant amount of material remains after 4 weeks, by 12 weeks the majority has been reabsorbed.

Level Of Evidence: NA Laryngoscope, 127:E166-E169, 2017.