Osseointegration of hydroxyapatite-coated, polyethylene-intruded and uncoated, sandblastered pure titanium implants in an infected implantation site. An experimental investigation in miniature pigs.

The authors studied the ingrowth dynamics of bone tissue into the pores of Hydroxyapatite-coated and uncoated wire-meshs of pure titanium in an infected implantation site. Samples of the tested materials were implanted into femora of 15 adult Göttingen minipigs. Just before implantation they were contaminated with Staphylococcus aureus. The animals were killed after 4, 8, 12 and 24 weeks. Undecalcified groundsections of bone tissue were prepared (app. 100 µm) for comparative histological evaluation. The HA-coated implants demonstrated advanced new bone formation after 4 weeks and nearly complete osseointegration after 12 weeks although all samples showed gross and histological signs of infection. Comparable reactions to the uncoated implants could only be observed after 24 weeks. Signs of degradation of the Hydroxyapatite-coating could be seen in contact to soft tissue and were more extensive compared to the behaviour in an uninfected site.