[Craniofacial augmentation with porous polyethylene implants (Medpor: first clinical results].

SUBJECT: Porous polyethylene (Medpor) is an alloplastic material commonly used in craniofacial reconstruction. We report about our first clinical experiences with Medpor for facial augmentation procedures. PATIENTS AND METHODS: We treated 27 patients between 2001 and 2005 (11 female, 16 male) with 48 Medpor-implants. The indications for application of porous polyethylene implants in our clinic were congenital malformations (15), post-traumatic defects (10), and reconstructions after tumor resection (2). The implants were used for nasal/paranasal augmentations (16), for zygomatico-orbital augmentations (18), and for augmentations of the chin and malar region (11). The procedures were performed in a standardized manner. We used prefabricated, self-contoured implants and fixed them subperiosteally with titanium osteosynthesis screws. All operations were performed under general anesthesia. We evaluated the aesthetic results and the ingrowth behavior clinically and histologically.
RESULTS: We achieved good aesthetic results and the patients showed no signs of discomfort or rejection. Four patients required a second intervention. These revision surgeries included two cases of local infections and two for aesthetic contouring. The necessary reduction of the implants allowed the harvesting of tissue and implant samples for microscopy.
CONCLUSION: Porous polyethylene implants showed a good fibrovascular integration without encapsulation under the light microscope. Giant cells were detected on the surface of the implants. Besides this there was evidence for resorption of the implant material. Fixation with titanium screws is very effective. No implant dislocation or implant fracture occurred. The implants showed high volume stability and were easily handled and contoured. It is not possible to visualize Medpor implants with current imaging techniques, because polyethylene shows no contrast.