The principal aim of this research is to develop a material suitable for a long-term percutaneous interface. Percutaneous devices (PDs) are implants which permanently penetrate through the skin through a surgically created cutaneous opening. Presently, there are implants designed for use as dental prosthesis; catheters for perfusion or dialysis; electrical connections for power, signals, probes, or detectors; skeletally attached artificial limbs; fracture fixation devices, and windows in the skin. Despite systematic studies of the pathophysiology of percutaneous interface healing, consistent long-term viability of the PD-tissue interface has not been achieved. For porous PDs it appears, however, that all presently known failure modes could be eliminated by decreasing the chronic inflammatory response and by increasing the rate and maturity of tissue ingrowth. Therefore, this study will examine the relationship of fiber diameter, pore size, fabric thickness, and preparation protocol to the chronic inflammatory response, as well as the rate and maturity of tissue ingrowth. Subcutaneous and percutaneous implants in dogs will help determine both the tissue response for various time periods and also the relationship of these responses to PD success. These results ultimately can be used to suggest design improvements for all porous soft-tissue implants in humans, not just for PDs. Analysis of implants will be done using optical microscopy (using both connective tissue stains and enzyme histochemistry), scanning and transmission electron microscopy, vascular microcasting, and interfacial peel stress analysis.
