화학공학소재연구정보센터
Materials Science Forum, Vol.426-4, 3219-3224, 2003
Bioactive PMMA bone cement prepared by chemical modification
Bone cement consisting of polymethylmethacrylate (PMMA) powder and methylmethacrylate (MMA) liquid is clinically used for fixation of implants such as artificial hip joint. The problem of the cement happens by loosening between the bone and the cement after a long implantation period, because it does not show bone-bonding ability, i.e. bioactivity. Development of bioactive PMMA cement has therefore been desired. The essential prerequisite for an artificial material to bond to bone is the formation of bone-like apatite layer on its surface when implanted in bony defect. This type of apatite layer can be formed even in a simulated body fluid (Kokubo solution) with similar ion concentrations to those of human extracellular fluid. It has been revealed that silanol (Si-OH) group and calcium ion (Ca2+) can be effective components to induce apatite nucleation on the surface of implant materials in body environment. In this study, we attempted to provide PMMA cement with, bioactivity by chemical modification using 3-methacryloxypropyl-trimethoxysilane (MPS), which provides Si-OH groups, as well as various calcium salts, which releases Ca2+. The cement modified with CaCl2, Ca(CH3COO)(2), Ca(OH)(2) or Ca(CH2=C(CH3)COO)(2) formed apatite within 7 days (d) in Kokubo solution, but not those modified with Ca(CH3CHOHCOO)(2) or Ca(C(6H)5COO)(2). Among the cements exhibiting apatite formation, those modified with Ca(CH3COO)(2), or Ca(OH)(2) showed compressive strength near or higher value than that required by ISO5833. Results on animal test indicated that the cement modified with Ca(CH3COO)(2) showed higher osteoconduction than the cement without modification. PMMA cement can be provided with bioactivity without appreciably degrading its mechanical properties, when kind of calcium salt is appropriately selected.