Delayed-onset of Pseudomonas infection in a hydroxyapatite orbital implant: a case report

Hydroxyapatite (HA) orbital implant, a multiple porous coralloid-like material, is frequently used in orbital reconstruction after enucleation or evisceration surgery. HA implants contain multiple interconnected pores in which rich fibrovascular tissue ingrowth could theoretically help to resist infection. Infection of hydroxyapatite implants are rare. Most HA implant infections occur before complete vascularization. We present this first case in Taiwan of delayed-onset Pseudomonas infection five years after receiving the HA implant. There was not much improvement after intensive medications, so removal of the implant was finally performed. The pathology study disclosed diffuse inflammatory cell infiltration in the whole implant with a necrotic central core. Rich fibrovascular ingrowth was also noted. Once a porous HA implant is infected, the infection is difficult to control and becomes more severe due to the dead space of the interconnected pores. Removal of the implant seems to be the only successful treatment modality.