The ENTific Centre
Porous polyethylene Medpor implants
This is a rigid implants material that resists shrink wrapping well. Its porous surface allows blood vessels and connective tissue to grow into the implant; this "vascularises" the implant. In addition the pore size of the implant is < 1µm; this is smaller than the dimension of bacterial organisms. Together the pore size barrier and vascularity helps to prevent infection. Adequate soft tissue coverage over all porous polyethylene surfaces is imperative to prevent complications of infection and extrusion (Berghaus et al). In the authors'opinion, clients with thicker nasal skin would be better suited as Medpor implant candidates when compared with thinner skinned individuals.
The Medpor implants are used for dorsal grafting and columella struts (Romo et al). They can be easily trimmed to size with the scalpel. Due to their rigidity, they are easy to use and quite firm to the touch beneath the tissue coverage. Medpor implants are however not as soft as, for example, silicone implants. Hence fine per-operative sculpturing of the porous polyethylene implant is not as easily performed and the use of cutting or diamond burr drills for sculpturing should be avoided as they seal off the porous surface. The implant is usually impregnated in a Betadine-saline solution prior to insertion, to further minimise bacterial soiling.
Medpor implants are ideal for structural grafting of the Asian columella. They provide strong tip support and projection (see Figure 12), improving the functional airway as well as the aesthetics. A pocket is fashioned between the meso-crural cartilages of the lower laterals into which the Medpor columella sheet is inserted; the implant sheet is then secured with ample soft tissue coverage. A word of caution for the patient – whenever Medpor implants are applied in the flexible lower third of the nose, the natural flexibility of the lower nasal tip will be impaired with a firm and relatively unyielding nasal tip to the touch as the final result.
Medpor implants are also suitable for dorsal augmentation in Asian rhinoplasty. Dorsal radix augmentation, where there is good soft tissue coverage, is excellent. The Medpor implant is placed in a subperiosteal pocket that is the usual 10% larger than its dimension; this prevents excessive postoperative implant migration. The conferred rigidity, when felt through the skin, of the Medpor radix implant mirrors that of the expected underlying nasal dorsum, and appears quite natural at this site.
The authors have also successfully applied Medpor dorsal implants to augment the dorsum e.g. for saddle nose deformity. However clinicians should probably exercise greater care whenever using, or extending, the Medpor implant over the dorsal aspect of the lower third of the nose i.e. in the supratip area. The relatively flexibility of this area of the nose, the closer proximity of the implant to the incisions and the relatively thinner mucosal tissue coverage, can potentially lead to higher implant loss rates here. Care should always be taken to ensure adequate soft tissue coverage over the implant at all times. In the event of infection with overlying erythema, appropriate antibiotic therapy should be instituted. Implant removal is necessary if there is no response to the antibiotic treatment or impending implant extrusion. Sharp dissection over the implant surface is required with a scalpel blade or sharp iris scissors, to divide the micro-vessels and connective tissue that would have grown in continuity into the implant body through the surface pores.