Biocompatible study of modified titanium skirt for keratoprosthesis

Objective The research is engaged in developing an improved titanium skirt for keratoprosthesis, the aim of this study was to evaluate biocompatible of keratoprosthesis of novel design.Methods The pure titanium skirt for keratoprosthesis with three hands were first Sandblasted, and then bioactive hydroxyapatite coated on Sandblasted titanium for keratoprosthesis by a acid-alkali chemical treatment. A total of 18 New Zealand white rabbits and 18 alkali burned rabbit corneas were respectively divided into three groups (Group A, B and C;Group E, F and G) with simple random sampling methods.The modified titanium skirt was inserted into the corneal stroma of Group A and E, and then the control skirt was inserted into Group B and F. Group C and H did not insert skirt as surgery control. The interfacial biointegration of skirt/cornea were examined under light microscopy by HE,TEM and SEM. The transparent center was implanted to rabbit corneas with modified titanium skirt after 3 months. Results Dense hydroxyapatite coating was deposited on the Sandblasted specimens by an acid-alkali chemical treatment. The number of corneal fibroblasts increased significantly in Group A compared with Group B, The extracellular matrix deposited on the surface of modified titanium skirt was more dense and tight than that of control skirt.There was a significant difference in the shear force of skirt among groups A and B (t = 3.297, P < 0.05 ), E and F(t =4.237, P <0.05),and taking out the skirt in Group A and E were more difficulty than that in Group B and F after 3 months. The observation of the tissue sections of modified skirt inserted eyes revealed that there were cells and collagen-like fibres perpendicular to or at an angle to the rough interface and the cellular function was extremely active, in accordance with the results of TEM. Compared with healthy host tissue, skirt/cornea healing after alkali burn was impaired. Conclusions Hydroxyapatite modified Sandblasted titanium skirt for keratoprosthesis can promote the interfacial biointegration of skirt and host cornea, no matter in healthy cornea or diseased cornea (alkali burn cornea). Hydroxyapatite coating improved the bioactivity of titanium. Key words: Prostheses and implants; Titanium; Hydroxyapatites; Eye burns; Biocompatible materials