Rheological properties of PMMA bone cements during curing

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Rheology

Background:

• Poly(methyl methacrylate) (PMMA) bone cements are widely used in orthopedic surgery.
• Understanding their rheological behavior during the curing phase is crucial for optimal handling and clinical outcomes.
• Current characterization often relies solely on viscosity, potentially missing key setting dynamics.

Purpose of the Study:

• To comprehensively characterize the rheological behavior of PMMA bone cements during curing.
• To investigate the influence of temperature on the viscosity-time profiles of these cements.
• To evaluate the utility of viscoelastic parameters in describing cement setting characteristics.

Main Methods:

• Utilized an oscillating parallel plate rheometer to measure rheological properties.
• Recorded viscosity as a function of time for various commercial PMMA bone cements.
• Conducted measurements across a temperature range of 19-25°C.
• Determined viscoelastic parameters including storage modulus, loss modulus, and phase angle.

Main Results:

• Observed distinct viscosity-time profiles among different commercial bone cements.
• Demonstrated a strong temperature dependence on the rate of viscosity increase.
• Documented the transition from viscous to elastic behavior as the cements cured, evidenced by changes in viscoelastic parameters.
• Showcased that viscoelastic parameters provide a more detailed description of the setting process.

Conclusions:

• Rheological characterization using viscoelastic parameters offers a more complete understanding of PMMA bone cement behavior than viscosity alone.
• These parameters may serve as improved indicators for assessing bone cement handling and setting characteristics.
• Temperature is a critical factor influencing the curing kinetics and rheological profile of PMMA bone cements.