BONE INGROWTH BEHAVIOR OF HYDROXYAPATITE-COATED, POLYETHYLENE-INTRUDED AND UNCOATED, SANDBLASTED PURE TITANIUM IMPLANTS IN AN INFECTED IMPLANTATION SITE - AN EXPERIMENTAL-STUDY IN MINIATURE PIGS

We studied the dynamics of bone tissue ingrowth into the pores of hydr oxyapatite-coated (plasma-spraying technique) and uncoated wire meshes of pure Ti in an infected implantation site. Samples of the test mate rials were implanted into the femora of 15 adult Gottingen minipigs. J ust before implantation they were contaminated with Staphylococcus aur eus. The pigs were killed after 4, 8, 12 or 24 weeks. Undecalcified gr ound sections of bone tissue were prepared and stained with toluidine blue for comparative histological evaluation. The hydroxyapatite-coate d implants already demonstrated advanced new bone formation after 4 we eks. By 12 weeks most of the implant pores were filled with newly form ed bone although all samples showed macro- as well as microscopic sign s of persistent infection. Comparable reactions of the uncoated implan ts could be observed only after 24 weeks. Signs of degradation of the hydroxyapatite coating were seen in contact with soft tissue. This was more extensive in the infected than in the uninfected site. The resul ts and possible clinical consequences are discussed.