Design of a ‘driven cylinder’ viscometer for bone cement rheological characterization

Abstract

The long-term success of surgical applications requiring bone cement is strongly influenced by the cement’s rheological properties. Previous studies showed a clear non-Newtonian, pseudoplastic, time-dependent rheological behaviour of acrylic bone cement during the working time. However, the particular nature of this material raises issues about its rheological characterization: the aim of this paper is to develop a new device, called ‘driven cylinder’ viscometer, able to accomplish the rheological characterization of acrylic bone cement. Three different fluids were tested by using the ‘driven cylinder’ viscometer: (a) liquid soap, (b) low-viscosity bone cement, and (c) vertebroplasty bone cement. For the sake of comparison, the rheological behaviour of the fluids (a) and (b) was also evaluated using traditional viscometers. The developed device allowed evaluation of the constitutive rheological parameters for non-Newtonian, power-law fluids. Independent evaluation of the viscosity of liquid soap and low-viscosity bone cement carried out by means of parallel-plate rotational rheometers showed a good agreement with the trends obtained by the ‘driven cylinder’ viscometer. The device versatility suggests its application for a complete description of pseudoplastic and time-dependent rheological properties of acrylic bone cements, which is a mandatory step for virtual tools of cement-based surgical procedures.