Clinical and histologic behavior of exposed porous high-density polyethylene implants.

Reconstruction in the head and neck is difficult and often requires complex solutions to restore functional and aesthetic form. While autogenous tissue is preferred, many alloplasts have been investigated. These materials, however, are foreign bodies, and most alloplasts tolerate exposure and infection poorly. An alloplast's in vivo behavior is a function not only of its composition but also of its form and macrostructure, as well as the interaction at the host-implant interface. Porous high-density polyethylene is well tolerated by surrounding tissue, and its porous core is rapidly infiltrated by host tissue. In order to further investigate the response of porous high-density polyethylene under adverse conditions, we implanted three porous high-density polyethylene disks and one silicone disk underneath the dorsal skin in each of 12 rats. The implants were exposed at differing times after implantation. After 7 days, the exposed areas were either skin grafted or allowed to close by secondary intention. Silicone implants all tolerated exposure poorly. Porous high-density polyethylene implants exposed soon after implantation also tolerated exposure poorly; however, none of these extruded. Porous high-density polyethylene implants exposed after the host tissue had invaded the pores tolerated exposure well, healing either by secondary intention or by skin grafting. Porous high-density polyethylene is a safe and reliable material for use in aesthetic and functional reconstruction of the head and neck. Porous high-density polyethylene and possibly other porous alloplasts tolerate exposure well once host fibrovascular tissue has invaded the implant pores. Further investigation of differing clinical settings and implant behavior is currently in progress.