Pre-clinical subdural tissue reaction and absorption study of absorbable hemostatic devices

SURGIFOAM (Absorbable Gelatin Sponge, USP), a new absorbable hemostatic sponge, GELFOAM (Absorbable Gelatin Sponge, USP) or Avitene (microfibrillar collagen hemostat) were evaluated in a three-month tissue reaction and absorption study in rabbits. Bilateral craniotomy was followed by subdural implantation of each hemostatic device. A sham control group was treated in a similar way except that no material was implanted. Implantation of these hemostatic devices for 15, 43, or 92 days did not result in any deaths or clinical neurobehavioral abnormalities, changes in cerebrospinal fluid, or significant macroscopic observations at necropsy. The tissue reaction to SURGIFOAM sponge was characterized by transient granulomatous inflammation that was slightly less intense than that observed for GELFOAM sponge which correlated to slightly longer absorption. In contrast, the tissue reaction to Avitene hemostat was characterized by moderate to marked granulomatous inflammation with an acute inflammatory component indicating a greater degree of tissue irritancy. Sequelae of this reaction were still observed at 92 days post-implantation. The tissue reaction in humans to SURGIFOAM sponge used as a hemostatic agent for neurologic surgical procedures is expected to be comparable to that observed with GELFOAM sponge, resulting in no significant adverse reactions for patients. This animal model was useful to assess the tissue reaction and absorption of biomaterials implanted in contact with the central nervous system, and it was able to differentiate between materials of biologic origin.