A Comparative, Long-Term Assessment of Four Soft Tissue Substitutes

Background: The ideal product for soft tissue replacement is durable, nonimmunogenic, and noninfectious. AlloDerm (LifeCell Corp., Branchburg, New Jersey), Enduragen (Stryker Corp., Kalamazoo, Michigan), and DermaMatrix (Synthes, Inc., West Chester, Pennsylvania) are frequently used for soft tissue replacement, but comparative analysis of these materials over an extended time period has not been reported. DuraMatrix (bovine tendon matrix; Stryker Corp.) is also promising, demonstrating desirable properties not only as a dural substitute but also for soft tissue replacement. Objectives: The authors analyze in vivo gross and microscopic changes over time with four commercially available dermal matrices, utilizing the murine model for a controlled environment. Methods: AlloDerm, Enduragen, DermaMatrix, and DuraMatrix implants measuring 1 x 1 cm were each implanted in 40 adult mice, in individual dorsal submuscular pockets. The mice were then sacrificed in groups of 10 at three, six, nine, and 12 months. The implants and surrounding tissues were excised and evaluated for gross and microscopic appearance. Results: Histological analysis of the specimens demonstrated similar encapsulation, implant infiltration, and surrounding inflammation over time. Enduragen implants demonstrated the least amount of host cell infiltration, whereas AlloDerm demonstrated the most. Grossly, Enduragen maintained its original shape and became firmer over time, whereas AlloDerm became spherical and softer. DermaMatrix and DuraMatrix both maintained their original shape and consistency. Implant migration, explantation, infection, or allergic reactions were not noted. Conclusions: All of the materials studied demonstrated high levels of host tolerance and tissue integration. AlloDerm demonstrated signs of resorption, whereas Enduragen maintained its size and became firmer in consistency. Together with the histological results, this suggests a proportional relationship between the amount of host cell integration and implant resorption.