We have studied a new adhesive
bone cement, that consists of 4-methacryloyloxyethyl trimellitate
anhydride (4-META) and
methylmethacrylate (MMA) as monomers, tri-n-butyl
borane (TBB) as the initiator, and
polymethylmethacrylate powder (4-META/
MMA-TBB cement). This cement has shown remarkable adhesive properties to bone in vitro. In this study, we assessed the interface in vivo periodically. The femora of rabbits were fenestrated and filled with either the 4-META/
MMA-TBB cement or a conventional
polymethylmethacrylate cement. The animals were killed after 1, 4, 12, and 24 weeks to analyze the interface by optical microscopy and transmission electron microscopy. Optical microscopic examinations showed that the cured 4-META/
MMA-TBB adhesive cement bonded to bone directly for 24 weeks, whereas a fibrous tissue layer was observed between the bone and cured conventional cement at 12 weeks after 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 the hybridized bone indicates the bonding mechanism of the
adhesive cement to bone, which prevents the
fibrosis intervention between bone and cement. These results suggest that the biomechanical and adhesive properties of 4-META/
MMA-TBB cement make it a useful bone-bonding agent in
orthopedic surgery.