Abstract
Abstract: :
Purpose: The hydroxyapatite implant is biocompatible, restores orbital volume and is fast gaining popularity as the implant of choice. It is thought that with its numerous tiny interconnecting pores, which encourage fibrovascular ingrowth, risk of implant migration is reduced, but the resulting spicules have been postulated to cause inflammation, edema and prevent epithelialisation. This is a comparison of the complications of the hydroxyapatite implant against non-integrated (acrylic, glass, silicon) implants. Methods: This is a retrospective comparative study of 59 sockets that were enucleated with implantation at the Singapore National Eye Center from January 1991 to December 2000. The outcomes measured were the complications of implant migration, exposure and extrusion, and conjunctival dehiscence. Statistical analysis was done using the two-sample test of proportion. Results: 21 patients had the hydroxyapatite implant and 38 patients had non-integrated implants ( 27 acrylic, 9 glass and 2 silicon). The mean duration of follow up was 2.7 years for the hydroxyapatite implant and 4.0 years for the non-integrated implants. 3 patients with pre-existing severe socket contracture before enucleation surgery was excluded from the statistical analysis. 5 cases of implant migration were encountered; all of these were sockets fitted with nonintegrated acrylic implants. Only one of these implants was wrapped with primary banked sclera while the other four were unwrapped. There was a higher rate of conjunctival dehiscence for sockets with hydroxyapatite implants (6 out of 21) as compared to sockets with non-integrated implants (3 out of 35). This was statistically significant (p=0.048; two-sample test of proportion). Conclusions: The hydroxyapatite implant, with its pores that allow fibrovascular ingrowth, has addressed the dreaded complication of implant migration following enucleation surgery. However, the spicules increase the risks of conjunctival dehiscence, and more basic research into the histopathological processes involved would contribute to our quest for the ideal implant. For the moment, the significantly cheaper non-integrated implants, when wrapped, may still have a very useful place in the rehabilitation of anophthalmic sockets.
Keywords: clinical (human) or epidemiologic studies: out • conjunctiva • wound healing