Osteogenetic activity of BMP-3-coated titanium specimens of different surface texture at the orthotopic implant bed of giant rabbits

Introduction: The successful combination of osteoinductive factors with cur rent materials used in both endoprosthetics and implantology improves bony ingrowth and long-term stability of the chosen implants. The aim of the pre sent experimental animal study was to clarify in what way faster bony integ ration can be achieved through additional BMP-3-coating of titanium test im plants of different surface textures (hydroxy-apatite-coated or corundum-bl asted). Methods: Thirty of 60 cylindrical titanium test implants with a hyd roxy-apatite or corundum-blasted surface were coated with 230 mug porcine, high-purified BMP-3-precipitate per implant to check their osteoinductive p otential in a bioassay. In each case a BMP-3-coated and an uncoated control -device were implanted with a gap formation of 1 mm. into the femoral part of the patellofemoral joint of the right and left leg of 30 adult giant rab bits. Serial saw slices of all explanted specimens were prepared, and the o sseous integration of the implant and time-dependent bone neoformation were analyzed microscopically and histomorphometrically 14, 35, and 56 days aft er implantation. Results: Coating of TiAl4V6-test devices with BMP-3 led in both groups after gap implantation to an improved osseointegration, that w as histomorphological and histomorphometrical verifiable. Statistical evalu ation using the t-test for matched samples showed 5 weeks after surgery a s ignificant higher volume of new formed bone of the BMP-3-coated corundum-bl asted or hydroxy-apatite-coated TiAl4V6 test devices compared to the non-co ated controls of the same type (P < 0.01). Light microscopy demonstrated os seointegration without connective tissue membrane around the surface of the implants after 2, 5, and 8 weeks. Better osseointegration was achieved in the hydroxy-apatite-coated implants than in the corundum-blasted implants. Conclusions: Our results indicate that composite metal implants, as used in endoprosthetics and implantology, are suitable carriers for BMP-3 and impr oved fixation of the implants can be achieved.