Introduction: All current soft tissue substitutes demonstrate various degrees of resorption and/or rejection. We assessed how chemical crosslinking of an available porcine dermal product affects tissue tolerance, tissue characteristics, long-term retention.

Methods: Twenty-four mice were subcutaneously implanted with a single 2 cm x 2 cm x 1mm material. Six mice were harvested at 3, 6, 9, and 12 months. In vivo implants were qualitatively assessed. Specimens were evaluated histologically. A pathologist assessed tissue response. Implant retention was determined by microscopy.

Results: All implants were thinly encapsulated indicating minimal foreign body response. One mouse (1/24) extruded the implant at nine months. All other implants demonstrated scattered areas of fibrovascular in-growth, which became apparent at the 6-month time interval and progressed. Many fibrovascular centers began to calcify and develop osseous-like growth cones envaginating the implant at 6 months. Qualitatively all implants became stiff with loss of pliability. Implants retained the original implant thickness of 1mm.

Conclusions: Collagen cross-linking improves long-term retention, but at the expense of losing pliability and soft tissue characteristics. Stiffness obviously impacts which planes can be implanted. The inability of collagenases to breakdown the implant may have significant consequences when implants do become infected.