Setting properties of four acrylic and two calcium-phosphate cements used in vertebroplasty.

STUDY DESIGN

Experimental study conducted in the laboratory with six different bone cements.

OBJECTIVES

To isolate the thermal properties of conventional and emerging bone cements used in vertebroplasty and to characterize their setting behavior.

SUMMARY OF BACKGROUND DATA

The heat released during setting has been linked to the desirable effects of pain relief and tumor destruction and to the undesirable effect of thermal necrosis of surrounding tissue. However, there are currently no studies that disconnect the exothermic reaction of the cements from the media in which they occur. Before the combined thermal effect is examined, it is important to understand the setting properties of cements alone.

METHODS

Thirty independent experiments were conducted with four PMMA cements (Cranioplastic, Vertebroplastic, Palacos LV-40, Antibiotic Simplex) and two calcium-phosphate cements (chronOS Inject and Biopex) in accordance with ASTM standard F 451-99a. A thermocouple was placed in the center of the cement mass, and the temperature-versus-time measurements were recorded.

RESULTS

The calcium-phosphate cements took over half an hour to reach their maximum temperature, which was only 3-4 degrees C higher than the ambient temperature. The temperature increase for the acrylic cements was between 16 and 23 degrees C, and it took about 15 minutes to reach the maximum temperature. The variation within the groups was also important.

CONCLUSION

The exothermic reaction of calcium-phosphate cements appears to be insignificant. Although the acrylic cements release considerably greater heat in a much shorter time period, it does not appear that their temperature is sufficiently high to cause extensive thermal injury. However, variations within each group must be considered along with the intended use when deciding on the cement to be used.