Ovine model for auricular reconstruction: porous polyethylene implants.

Objectives: We developed a large animal model for auricular reconstruction with engineered cartilage frameworks and evaluated the performance of porous polyethylene auricular implants in this model. Methods: Eighteen high-density porous polyethylene auricular frameworks were implanted subcutaneously in the infraauricular areas of 9 sheep. The implants were harvested 17 weeks later for gross and histologic examination. The perioperative and postoperative courses were carefully documented. Results: Five implants became exposed, and 2 implants needed to be removed at 7 weeks. Additionally, 1 infected implant was removed at 2 weeks. Seromas developed in 2 implants because of drain failures and were drained successfully during the first postoperative week. There were no other surgical site complications. The remaining 10 implants had an acceptable cosmetic appearance at 17 weeks. Conclusions: The perioperative complication rate in the ovine porous polyethylene auricular implant model was higher than that reported for auricular reconstructions in humans. The implant exposures were likely caused by ischemia and excessive stress on the thin overlying skin, because vascularized flap coverage was not used. The histologic findings were comparable to the results reported for other animal models. This large animal model is appropriate for auricular reconstruction experiments, including engineered constructs.