Thermal Curing and Strength of PMMA Bone Cement

Many current bone cements have proprietary minor ingredients that affect the chemical kinetics and heat transfer modeling of the exothermic reaction during bone cement polymerization. In addition, the geometry and the method of cooling/curing the bone cement can vary by application. A method for modeling energy generation, based on temperature measurement of various geometries and conditions, expresses the exothermic reaction and the duration with respect to time. Reaction from the bone cement can yield temperatures above 110°C for the air convective cooling boundary condition. Experiments show that by using cold irrigation cooling (saline) with an initial temperature of 1.5°C, the maximum reaction temperature of the PMMA cement approaches 40°C depending upon the thickness of the cement. For bone cement cooled in air and saline at room temperature, the exothermic reaction begins around 400 seconds (8 min) after the compounds are mixed. When cold saline is applied, the time-delay of the reaction is approximately 300 additional seconds compared to the two room temperature cases. Finally, based on compression testing, the structural behavior of the PMMA cement is improved when the material is cured in a slower and wet environment.