The resorption of bone-implanted corals varies with porosity but also with the host reaction.

Three different exoskeletons of coral species Porites asteroides (P), Montastrea annularis (M), and Dichocoenia stokesi (D) were implanted for 2-20 weeks in rabbits. At 2, 4, 8, or 20 weeks, the exoskeletons presented variations in their resorptions depending on the species. To understand the variations in the decreasing speed of the implants despite their similar chemical composition, a study of the surface and architecture of the coral was carried out using scanning electronic microscopy, porosity was evaluated, and growth and differentiation of osteogenic cells cultured in vitro were observed for more than 1 month. At the cellular level, the surface of the implants was identical. Three-dimensional structures of the implants were variable, but the porosity values [P = 42.7%, M = 40.7%, and D = 17.4%] could not completely account for the differences in the resorbing process of the species. Standard histologic studies performed at 2, 4, 8, and 20 weeks after implantation produced the same pattern with P or M, showing aspects of rapid resorption; however, with D there were images resembling those of a foreign-body reaction. It seems that when resorption is not quick enough, a foreign body reaction develops which further slows down the process. This work focuses on the importance of porosity when using coral as bone substitute.

Corneal ulcer due to Exserohilum longirostratum.

A 47-year-old man sustained a traumatic injury to the left eye, and a corneal ulcer subsequently developed. Histologic examination of the corneal tissue revealed septate hyphae with acute angle branching. The mycologic and bacterial cultures yielded a dematiaceous fungus with ellipsoidal pigmented macroconidia borne sympodially on geniculate conidiophores. The multicellular macroconidia had prominent, protruding, truncated hila. The shorter macroconidia averaged 5-7 septa, and the longer conidia 13-21 septa. Growth on V-8 agar, alternating between fluorescent light and the dark, produced macroconidia more than 200 microns in length. The isolate was identified as Exserohilum longirostratum. This is believed to be the first documented case of mycotic keratitis caused by the phaeohyphomycete E longirostratum.

The use of natural Caribbean coral as a bone substitute in bone grafts: results after four years - abstract

The Caribbean coral Porites astreoides was selected for use as a bone substitute in humans after several animal experiments. Coral was used as a bone substitute in 47 cases comprising 23 tibial plateau fractures, 4 benign osseous tumours, 4 cases of cortical defects of the femur and tibia following fractures, 2 cases of tibial osteotomy, in 8 patients undergoing total hip arthroplasty and in 6 other orthopaedic patients. In follow up 6 months to 4 years, X-rays revealed resorption and new bone formation in place of the coral which behaved very similar to bone grafts. The indications for using coral as a bone substitute, the complications and detailed results are described (AU)