Rheological properties of acrylic bone cement during curing and the role of the size of the powder particles

Abstract

A dynamic compressive rheometric technique was used to determine the true or complex viscosity (eta*) of three poly (methyl methacrylate), PMMA-based bone cement formulations (one commercially available and two experimental), as a function of the time that elapsed from commencement of hand mixing of the cement constituents (t). For each cement, two rheological parameters [namely, the time of onset of cure (t(ons)) and the critical cure rate (CCR), which is herein defined as the complex viscosity rate computed at t(ons)] were determined from the eta*-t data. For each cement, particle analysis was used to obtain the powder particle size distribution, from which the following parameters were obtained: (a) the overall mean particle diameter D(m), and (b) the relative amounts of small-sized PMMA beads (mean diameter d between 0 and 40 mum) (alpha) and large-sized PMMA beads (d > 75 mum) (beta). It is seen that the key particle parameter is not D(m) per se but alpha and beta. Thus, the highest values of t(ons) and CCR were obtained from a cement with the highest values of alpha and beta. An explanation for these trends is given, and two areas for further research work in this field are outlined.

A Review of PMMA Bone Cement and Intra‐Cardiac Embolism

“…These pores are postulated to act as sites for the initiation of cracks which contribute to the aseptic loosening of the prosthesis [25]. During the bone cement curing, initially the rise in viscosity is largely due to the swelling of the polymer particles in the monomer, while polymerization of the monomer also contributes and finally dominates the rise in viscosity at later times, suggesting a strong temperature dependence of the viscosity-time profiles [26].…”

The Chemistry of Acrylic Bone Cements and Implications for Clinical Use in Image-guided Therapy

“…Samples containing PMMA particles with larger mean diameters and widespread distributions of particle size had lower peak polymerization temperatures and longer setting times (16,26). Aside from its structural role as a component of the cement matrix, PMMA beads serve as a heat sink-dissipating energy released by the exothermic polymerization of MMA monomers.…”

Preparation and Characterization of Injectable Brushite Filled-Poly (Methyl Methacrylate) Bone Cement

“…There is an agreement within the literature that smaller particle size can result in increased viscosity of polymer systems because they tend to form particle networks that produce a yield phenomenon [27,28]. When adding CaP fillers in bone cements, several events can lead to an increase in viscosity and degradation of the material handling including: (1) increased particle volume in the mixture can lead to difficult wetting of the components of the cement mixture; (2) particle-particle interaction and network formation may lead to clumping of the filler phase; and (3) phase separation or filter-pressing [29].…”