Biomechanics and leakage rate of high and low viscosity bone cement after vertebroplasty

Abstract

Objective To explore the differences of biomechanics and leakage rate in high and low viscosity bone cement after vertebroplasty and to analyze the reasons. Methods Forty-two vertebral bodies were harvested from 6 embalmed cadavers. All specimens were subjected to the X-ray examination to exclude tuberculosis, tumor and other diseases. Thirty-six vertebral specimens with similar bone density were selected. All specimens were selected to make into compression fracture model by the biomechanical machine for further test. The model of compression fracture was divided into two groups randomly: A and B (n=18 each). The group A was injected with low viscosity bone cement and the group B with high viscosity. The biomechanical testing was carried out before the fracture and after cement injection. The cement leakage rate and distribution of cement were assessed with the reference of postoperative CT scan. Results In group A and group B, the maximum vertical load and stiffness after cement injection were (3 761.03±693.55) N, (3 965.31±999.90) N; (472.27±52.05) N/mm, (1 039.38±345.11) N/mm, respectively. After vertebroplasty, the maximum vertical load showed no significant difference between 2 groups. (Z=-0.127, P=0.450), and the stiffness was statistically significant (Z=-5.125, P=0.000). The leakage rate was significantly higher in group A (44.44%) than in group B (11.11%) (P=0.026). Conclusion High viscosity bone cement can increase the stiffness of vertebral body and have little effect on the maximum vertical load in comparison to the low viscosity. Furthermore, the high viscosity significantly decreases the rate of bone cement leakage. Key words: Vertebroplasty; High, low viscosity bone cement; Biomechanics; Bone cement leakage rate