Rheological properties of PMMA bone cements during curing.

The rheological behaviour of poly(methyl methacrylate) bone cements has been characterised during the curing phase using an oscillating parallel plate rheometer. Viscosity has been measured as a function of time for a range of commercial cements showing different viscosity-time profiles. Measurements have been made over a range of temperatures from 19-25 degrees C, and the results show a strong dependence of rate of viscosity rise on temperature. Viscoelastic parameters, such as storage modulus, loss modulus and phase angle have been obtained and show the change from primarily viscous to elastic behaviour as the cements set. It is suggested that these parameters more completely describe the rheological behaviour of bone cements than viscosity alone and may provide a better measure of handling and setting characteristics.