Ultrasonic characterization of the curing process of hydroxyapatite-modified bone cement

Ultrasonic parameters such as velocity of sound and broad-band ultrasonic a ttenuation (BUA) are sensitive to changes in the viscoelastic properties of a material. Bone cement undergoes changes is these properties as it cures. By monitoring the propagation of ultrasonic pulses through a sample of cur ing bone cement, the curing reaction of polymethylmethacrylate-based (PMMA) bone cement was investigated for hydroxyapatite (HA) concentrations of 0, 10, and 30% (by weight). As the material hardens, the velocity of sound inc reases by 70%. BUA shows a large peak at the midpoint of the velocity trans ition. These data are used to compare the cure time and cure duration for P MMA bone cement mixed with hydroxyapatite particles. Measurements of the fi nal sound velocity and BUA were also performed to investigate the mechanica l properties of the fully cured cement, and to compare to compression testi ng data. This is the first time the curing process of bone cement has been investigated as a function of hydroxyapatite concentration. Results indicat e that the cure time is not significantly affected by the addition of HA pa rticles, and that both velocity of sound and BUA are sensitive to the curin g process. (C) 2001 John Wiley & Sons, Inc.