Scanning electron microscopic examination of porous orbital implants

To compare the structural makeup of five porous orbital implants: two made of coralline hydroxyapatite (Bio-Eye and Chinese implant), one of synthetic hydroxyapatite (FCI), one of porous polyethylene (Medpor) and one of alumina. The Bio-Eye, Medpor and alumina implants are currently available in Canada.

Pore size, pore interconnectivity and microcrystalline architecture.

The Bio-Eye had multiple interconnected pores ranging from 300 microns to 700 microns in width; higher-power views showed coarse-appearing crystals approximately 2 microns wide. The FCI implant showed similar interconnectivity of the pores but fewer pores, which were about 300 microns to 500 microns in size. Higher-power views showed hexagonal crystals about 1 micron to 5 microns in size. The Chinese hydroxyapatite implant had multiple interconnected pores ranging from 200 microns to 700 microns in size. The crystals were similar in appearance to those of the Bio-Eye but were smaller and more granular. The 150-micron pore size Medpor implant had irregularly shaped pores ranging from 100 microns to 500 microns in size. The 400-micron pore size implant had pores that looked more like channels that coalesced; the pores and channels ranged in size from 125 microns to 1000 microns. In both cases higher-power views showed a woven texture. In the alumina implant the pores were well connected and evenly distributed and were approximately 500 microns in size. On high-power studies the implant showed a cobblestone-like pattern of crystals approximately 4 microns to 5 microns wide.

There are notable differences in pore size, pore interconnectivity and microcrystalline architecture between the implants studied. These features may be important in the overall biocompatibility of the implant.