Histopathological and scanning electron microscopy findings of retrieved porous polyethylene implants.

Porous polyethylene (PPE) implants are biocompatible alloplastic materials commonly used for facial augmentation. However, the effect of sub-periosteal PPE application on the surrounding tissues has not been analyzed clearly. This report documents the case of a 22-year-old woman who underwent peri-alar augmentation with PPE to improve midface retrusion. Although no infection or inflammation occurred at the surgical site, the patient requested removal of the PPE implant for aesthetic reasons alone at 1 year after the surgery. The removed implant was subjected to histological and morphological evaluation using conventional histological staining and scanning electron microscopy (SEM). Histopathological staining revealed bone ingrowth into the pores of the implant near the boundary with the host bone. Little evidence of a foreign body reaction was observed. SEM revealed densely arranged collagen fibres and osteoblastic cells in the pores. Moreover, the outer surface of the PPE implant in contact with the periosteum showed fibrous tissue ingrowth, leading to tissue adhesion. These findings confirm bone ingrowth into the PPE pore structure in humans.