Freeze-dried human cancellous bone as orbital implant in an animal model

Abstract

Objective: To determine if freeze-dried human cancellous bone is biocompatible and can be used as an integrated orbital implant.

Methods: This is an experimental study of 10 rabbits that underwent unilateral enucleation with placement of a 14mm spherical orbital implant made from freeze dried cancellous bone of human femoral heads. The implants were harvested after six weeks. Grossly, the rabbits were observed for occurrence of inflammation and implant extrusion. Histologically, the extent of fibrovascular ingrowth was assessed.

Results: Six rabbits completed six weeks of observation. All implants were exposed at the time of harvest, although there was no evidence of gross infection or inflammation. None of the implants were extruded. Fibrovascular ingrowth was observed in the outer third zone. A few plasma cells were seen, mostly in the periphery, and scattered among red blood cells in the center of the implant.

Conclusions: Orbital implant made from freeze-dried human cancellous bone is comparable to commercially available porous implants with regard to the presence of fibrovascular ingrowth when implanted in rabbit eyes. This lessens the chance of implant extrusion. The absence of implant rejection in this study is an encouraging indication that it should be tested in humans.