A new variety of hydroxyapatite: The Chinese implant

Purpose: This study was designed to evaluate a new type of hydroxyapatite (HA) implant (produced in China) in a rabbit model. Methods: Three New Zealand white rabbits underwent enucleation of one eye followed by implantation of a 12-mm Chinese HA implant wrapped in Vicryl mesh (polyglactin 910). Magnetic resonance imaging was performed to assess host fibrovascularization of the implant 4, 8, and 12 weeks after implantation. One animal was sacrificed at each of these times for histopathologic examination. The Chinese implant was also examined chemically and by scanning electron microscopy. It was compared to the original BioEye and the third generation synthetic HA implant produced in France by FCI (FCI3). Results: This new variety of HA implant from China is heavier than the FCI, implant but lighter than the original BioEye. The Chinese implant was easy to work with and not fragile. The pore size was more uniform than the FCI, implant and similar to the BioEye implant clinically and by scanning electron microscopy. The pores in this implant are unidirectional. Analysis for impurities revealed a calcium oxide (CaO) content of 4.4%. Histopathologically, central vascularization occurred by 4 weeks and was similar in extent to the vascularization seen with the FCI, implant and the BioEye. Conclusions: The Chinese implant is less expensive then the BioEye and the FCI, implants, and appears to be a viable alternative to the BioEye. Further refinements are in progress to eliminate the CaO contaminant.