STANDARDIZED INFECTION MODEL FOR EXAMININ G THE BONY INGROWTH DYNAMICS OF HYDROXYLAPATITE-COATED AND UNCOATED PURE TITANIUM MESH IN THE PIGFEMUR

The authors studied the ingrowth dynamics of bone tissue into the pore s of Hydroxyapatite-coated (plasmaspraying technique) and uncoated wir emeshs of pure titanium in an infected implantation site. Samples of t he tested materials were implanted into the femora of 15 adult Gotting en minipigs. Just before implantation they were contaminated with Stap hylococcus aureus. The animals were sacrificed after 4, 8, 12 and 24 w eeks. Undecalcified ground-sections of bone tissue were prepared (app. 100 microns) and stained with toluidin blue for comparative histologi cal evaluation. The HA-coated implants demonstrated advanced new bone formation already after 4 weeks and nearly complete osseointegration a fter 12 weeks although all samples showed gross and histological signs of persisting infection. Comparable reactions of the uncoated implant s could only be observed after 24 weeks. Signs of degradation of the H ydroxyapatite-coating could be seen in contact to soft tissue and were more extensive compared to the behaviour in an uninfected site. The r esults and possible clinical consequences are discussed.