Late infection of hydroxyapatite orbital implants.

BACKGROUND

Exposure and minor complications of hydroxyapatite orbital implants are common. Infection appears to be rare and fibrovascular ingrowth into hydroxyapatite implants may make infection and extrusion less likely than with other types of orbital implant.

METHODS

We describe three cases of chronic low-grade infection of hydroxyapatite implants, occurring late after apparently uncomplicated surgery, with tiny or inapparent areas of conjunctival loss or exposure.

RESULTS

Two of the three cases grew Staphylococcus oureus on culture. All three implants ultimately needed to be removed. A characteristic histological pattern was seen, with abrupt transition between vascularized and abscessed implant.

CONCLUSIONS

Chronic infection of hydroxyapatite implants can occur late, in the absence of large conjunctival defects, or other obvious risk factors. While exposure of the implant to pathogens through a breach in the conjunctiva may have been a factor, it appeared that the infection may have arisen in an avascular portion of the implant prior to the conjunctival breakdown in one or more of these cases.