| Summary: | Acrylic bone cement is used in orthopaedic surgery for total joint replacements as a means of fixation of the prosthesis to the bone. One of the main problems associated with total joint replacements is aseptic loosening which can be caused by the brittle fracture of the cement. The purpose of this research was to improve the resistance of bone cement to brittle fracture by creating new experimental cements containing the thermoplastic rubber, acrylonitrile-butadiene-styrene (ABS), and to determine if improvements could be furthered by using ABS surface coated with a silane coupling agent, the latter having never been investigated before. Incorporating the ABS into the cement will affect the cements' rheological/handling characteristics, therefore these properties were investigated over the entire curing process both at 25 C and 37 C. The results showed that the introduction of either ABS or silane-coated ABS significantly improved the fracture resistance of the cement. The fracture toughness of cements containing 30% ABS increased by 19%. and 40% silane-coated ABS by 31%. There was also a substantial improvement in fatigue crack propagation behaviour with cements containing 30% and 40% ABS or silane-coated ABS showing a minimum three-fold increase in stress intensity at failure. Furthermore, by monitoring changes in the rheological properties over the entire curing process it was found that the incorporation of silane-coated ABS particles increased the maximum complex viscosity by 35% and maximum elastic modulus by 33%. The curing rates of the cements containing 30% and 40% ABS/silane-coated ABS remained comparable with commercial cements. These results are of major significance as the enhanced ability of the new acrylic cements to resist catastrophic failure by brittle fracture could dramatically lengthen the working lifetime of a total joint replacement.
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