Influence of powder-to-liquid monomer ratio on properties of an injectable iodine-containing acrylic bone cement for vertebroplasty and balloon kyphoplasty.

The interventional radiological techniques of vertebroplasty (VP) and balloon kyphoplasty (BKP) are widely used in cases where the pain secondary to compression fractures of vertebral bodies is severe, persistent, and refractory to conservative treatments. In the majority of VP and BKP cases, an injectable poly(methyl methacrylate) (PMMA) bone cement and different values of powder-to-liquid monomer ratio (PLMR) are used. A systematic study of the influence of PLMR on relevant cement properties is lacking. This was the subject of the present study, with the injectable PMMA bone cement used being an experimental one whose radiopacity is provided by an iodine-containing compound in the powder. The PLMRs used-1.54, 2.22, and 3.08 g mL(-1)-are within the range used in clinical reports on VP and BKP. One property of the curing cement, namely, the polymerization rate at 37 degrees C (k'), was estimated using nonisothermal differential scanning calorimetry results. The fatigue lives (N(f)) of cured cement specimens were obtained under axial loading corresponding to axial stresses (S) of +/-20.0, 15.0, 12.5, and 10.0 MPa, at a frequency of 2 Hz. The fatigue limit of the cement was estimated from the fit of the S - N(f) results to the Olgive equation. With increase in PLMR, k' increased significantly, but the influence of PLMR on the fatigue limit and on another property also estimated from the S - ln N(f) results is not significant.