M. Habib, M. Rudolph,C. Marchek, H. Serhan, G. Baroud
(Sherbrooke,Canada-Rayham, MA USA)
Vertebral body augmentation has recently evolved as a medical procedure for the treatment of vertebral compression fractures related to osteoporosis. Though this procedure has been reported to be effective, cement leakage into the spinal canal and/or the cardio vascular system may lead to serious complications. This study compared the cement leakage, filling behaviour and intravertebral pressure of two existing delivery systems (Confidence and Vertebroplastic). The comparison was performed using an established benchmark model  wherein the cement leakage, filling behaviour can be assessed.
Three groups related to Vertebroplastic system and cement were injected at 3.5, 6.5, and 9.5 minutes after admixing the powder and monomer respectively. The two other groups related to the system in that the first and second groups were injected at 3.5 and 6.5 minutes, respectively. An experimental leakage model developed in a previous study  was used to examine the filling and leakage behaviour of the two spinal augmentation systems. Cement-filling patterns in the model were quantified by analyzing the filling images with a special Matlab code. Furthermore, the intravertebral (IV) pressure value in the simulated vertebral model was measured using a double-conduit introducer needle.
The CONFIDENCE groups showed significantly less leakage than the vertebroplastic groups. The average leakage masses of 0.93 g (±0.6) and 1.52 g (±1.17) were observed for the confidence groups injected at 6.5 and 3.5 minutes respectively. In the case of the vertebroplastic system, the average leakage masses were 2.32 g (±1.08), 3.20 g (±1.05) and 4.32 g (±0.57) for the group delivered after 9.5, 6.5 and 3.5 minutes respectively. The Confidence groups showed significantly higher filling uniformity compared to the vertebroplastic groups [Fig.1]. However, there were no significant differences between the two groups of the confidence systems as the ANOVA showed (F=0.88227, P=0.43099). The minimum IV pressure was 0.39 psi and the maximum was 0.65 psi (F= 0.44, P= 0.65) in the case of the Vertebroplastic system. The minimum IV pressure 0.16 Psi, and the maximum was 0.82 psi (F= 0.02, P= 0.89) for the Confidence system.
Fig. 1: Representative sample of the filling pattern. C: CONFIDENCE system, V: VERTEBROPLASTIC system, a: injection stared after 3.5 min, b: injection started after 6.5 min, c: injection started after 9.5 min.
The confidence system is a high viscous cement system with the objective to curtail the cement leakage and improve the cement filling uniformity. The results of the study showed significantly superior results for the confidence system. Specifically, the filling uniformity increased and the cement leakage reduced in all confidence groups if compared to the vertebroplastic groups. There was no significant increase in the intravertebral pressure when the cement was delivered at a later point of time.
(1) G. Baroud, et al, Spine 2006;31(22):2562-68.