A COMPARATIVE STUDY OF INHIBITORY EFFECTS ON PERI-IMPLANT OSTEOLYSIS BETWEEN ANTI-TNFA AND BISPHOSPHONATE IN A RAT MODEL

This study examined the inhibitory effects of anti-TNF-a antibody (anti-TNF) and a new bisphosphonate (TRK-530) on peri-implant oseteolysis in a rat model with continuous infusion of polyethylene particles. TRK-530 is a novel synthetic bisphophonate to have a direct effect on osteoclastic bone resorption as well as suppressive effects on bone resorbing cytokines from macrophages. Materials and methods: Sixty Wister rats were randomized to three groups (n=20 each). In each rat, a Kirshner wire (K-wire) was inserted into the femur and polyethylene particles (HDPE, mean size; 2 microns) were continuously infused into the knee joint using an osmotic pump. The animals were subcutaneously injected with saline (control group) or 1 mg/kg of TRK (TRK group) or intraperitoneally injected with 100 mg of anti-TNF (anti-TNF group) every second day after surgery until 8 weeks. At 4 weeks or 8 weeks after surgery, rats were sacrificed. Rdiographs were evaluated for the presence of osteolysis, thereafter, garnulation tissues were stored for PCR analysis for IL-1 mRNA as well as TNF-a mRNA. Then, femurs were prepared for the histology. Results: Radiographic peri-implant osteolysis was seen more frequently in TRK group compared to other two groups (p Discussion: The present study demonstrates that cumulative effects of TRK such as the suppression of bone resorbing cytokines as well as direct suppression of osteoclasts reduce the polyethylene induced peri-implant osteolysis. In addition, single anti-cytokine therapy appears not to be enough to inhibit peri-implant osteolysis in our model.