Bending properties of wire-reinforced bone cement for applications in spinal fixation

PMMA beam specimens were tested in four-point bending to determine if the bending strength of acrylic bone cement, as used in posterior spinal fusion, could be improved by metal-wire reinforcement. The result showed that the load-carrying capacities of 1- and 0.5-mm diam stainless-steel-wire-reinforced PMMA specimens in bending were significantly higher than similar unreinforced normal PMMA samples. On an average, steel reinforcement comprising approximately 1% of the cross-sectional area of the PMMA specimens caused a 15% increase in bending strength. Even after the cement fractured, the reinforcing wires still sustained an appreciable amount of bending moment, thus preventing catastrophic failure of cement alone.