Prevention of fibrous layer formation between bone and adhesive bone cement: In vivo evaluation of bone impregnation with 4-META/MMA-TBB cement

We have studied a new adhesive bone cement, that consists of 4-methacryloyl oxyethyl trimellitate anhydride (4-META) and methylmethacrylate (MMA) as mo nomers, tri-n-butyl borane (TBB) as the initiator, and polymethylmethacryla te powder (4-META/MMA-TBB cement). This cement has shown remarkable adhesiv e properties to bone in vitro. In this study, we assessed the interface in viz,a periodically. The femora of rabbits were fenestrated and filled with either the 4-META/MMA-TBB cement or a conventional polymethylmethacrylate c ement. The animals were killed after 1, 4, 12, and 24 weeks to analyze the interlace by optical microscopy and transmission electron microscopy. Optic al microscopic examinations showed that the cured 4-META/MMA-TBB adhesive c ement bonded to bone directly for 24 weeks, whereas a fibrous tissue layer was observed between the bone and cured conventional cement at 12 weeks aft er the operation. The transmission electron microscopy views of 4-META/MMA- TBB cement bonded to bone demonstrated a unique "hybridized bone" with the cement in the subsurface of the substrate in every case. The formation of t he hybridized bone indicates the bonding mechanism of the adhesive cement t o bone, which prevents the fibrosis intervention between bone and cement. T hese results suggest that the biomechanical and adhesive properties of 4-ME TA/MMA-TBB cement make it a useful bone-bonding agent in orthopedic surgery . (C) 2000 John Wiley & Sons, Inc.