Clinical and Histologic Behavior of Exposed Porous High-Density Polyethylene Implants

Abstract

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.

Comparison of alloplastic implants for facial bones by scintigraphy and histology: an experimental study

“…Two months after implantation, there was complete or near complete accumulation especially in the hydroxyapatite implants scintigraphically and the histological examination revealed vascularisation and new bone formation. Although the pore size (125 to 200 mm) of porous polyethylene is suitable for bone ingrowth, only fibrous tissue ingrowth was observed as reported by other investigators [10,13]. Slight increase (+ or ++) in tracer accumulation was noted in the porous polyethylene implant region two months after surgery but there was no osseous formation inside the pores.…”

“…Autologous tissue has the morbidity of harvesting, the difficulty of remodelling in addition to the limited amount available [13]. Materials investigated for this purpose are chemically diverse and include ceramics, composites, bone derivatives, and natural and synthetic polymers.…”

Modified Turkish delight: morcellized polyethylene dorsal graft for rhinoplasty

“…Its large pore size, allows for aggressive soft tissue infiltration and long-term stabilization. Resistance to extrusion has been noted in several studies 8 . Ingrowth of the wellvascularized connective tissue, with minimal foreign-body reaction, gradually decreasing over time after implantation, indicates excellent biocompatibility and the probability of indefinite stability of the polyethylene implants used for reconstruction of the nasal dorsum 6 .…”

Evaluation and Management of Exposed High-density Porous Polyethylene Implants

“…On the other hand, the additional morbidity and time of harvesting, high resorption rates and limited availability of donor tissue force the surgeon to use alloplastic materials. 3,8,9 The accelerated development in biomaterial technologies helped to reach the almost-ideal implants, but unfortunately, various disadvantages with each still occur occasionally.…”

“…Some authors believe that exposures are secondary to ischemic damage of the overlying skin; they also feel that the HDPPE implants are not extruded because of the stabilization afforded by the surrounding fibrous ingrowth. 8 In this study we aimed to evaluate the exposed implants and management of the exposed implants with various procedures because there is no consensus or algorithm for the exposed HDPPE implants.…”