Cement leakage and filling pattern study of low viscous vertebroplastic versus high viscous confidence cement.

Background: Vertebral augmentation has recently evolved as a medical procedure for the treatment of vertebral compression fractures, the most common type of skeletal fractures related to osteoporosis.

Methods: This study compared the cement leakage and filling behavior of 2 existing delivery systems (Confidence and Vertebroplastic; DePuy Spine, Raynham, MA). The Confidence system with the high viscosity cement has been recently introduced in an attempt to curtail cement leakage.

Results: The comparison was performed using an established benchmark model wherein the cement leakage, filling behavior can be assessed. A double-conduit introducer needle was used to deliver the cement and to measure the intravertebral pressure while delivering the cement. There were 5 experimental groups in this study: 3 low-viscosity groups, whose cement was injected at 3.5, 6.5, and 9.5 minutes after admixing the powder and monomer, and 2 high-viscosity groups injected at 3.5 and 6.5 minutes. The mass of leaked cement generally decreased with delaying the start of the injection. Specifically, for the low-viscosity, the average smallest leakage mass obtained was 2.6 ± 1.2g when the cement was delivered at 9.5 minutes. If delivered after 3.5 minutes, the mass of cement leak was 4.0 ± 1.2g. The high-viscosity system has showed improved results in curtailing cement leakage, as compared to low-viscosity. Specifically, if injected after 3.5 and 6.5 minutes, the cement leakage amounts were 1.5 ± 1.2g and 0.92 ± 0.6g, respectively. Similarly, the uniformity of cement filling increased when the delivery was delayed and when the high-viscosity system was applied. Furthermore, there were no significance changes in the intravertebral pressures between the low- and high-viscous groups. No correlation between the leakage mass and the IV pressures was noted.

Conclusion: The cement thickness and timing of delivery are key in controlling the intravertebral cement filling and physician may want to explore the use of low- or high-viscous cement for different fractures. The thickness of the cement has no significant impact on the intravertebral pressures.