Effect of distribution of quantitative bone cement on improving total stiffness of osteoporotic vertebrae:an finite element analysis

CHEN Bailing; LIN Tao; XIE Denghui; ZHANG Meichao; CUI Haowen

doi:10.3969/j.issn.1674-666X.2015.03.006

Abstract：Objective To evaluate the effect of different distributions of quantitative bone cement on improving total stiffness of osteoporotic vertebrae after bone cement augmentation by finite element (FE) analysis. Methods We choose a female cadaver and then three-dimensional FE models of the osteoporotic L1 vertebral body (VB) were built. Bone cement augmentation of L1 was simulated in this numerical study. VBs <br> were divided into five groups based on the volume and distribution of bone cement: Group A (4.5 mL), the cement augmentation was limited to hemivertebral bodies; Group B (4.5 mL), the cement augmentation was located in the middle and symmetrically reached one quarter of both sides of the VB; Group C (4.5 mL), the bone cement was located in the middle and symmetrically reached half of both sides of the VB; Group D (4.5 mL), the cement augmentation was located in the middle and symmetrically reached three quarters of both sides of the VB; Group E (9 mL), bi-pedicular bone cement augmentation. Changes of total stiffness in all models with cement augmentation were compared with those in the corresponding unaugmented models, and the differences of total stiffness among the different groups were evaluated under axial compression loads. Results The total stiffness of VBs of each group was markedly increased compared with the osteoporotic, untreated model (P <0.05). The total stiffness of group E was significantly higher than group A, C and D, respectively (P<0.05), and there was no significant difference between group B and E (P >0.05). Moreover, the total stiffness of group B was 33.9%, 27.2% and 34.1% higher than group A, C and D, respectively (P <0.05), and there were no significant differences among group A, C and D (P >0.05). Conclusion When bone cement is being quantified, the total stiffness of osteoporotic VB improved by cement distribution in the middle of the VB is superior to uni-pedicular or symmetrically diffused cement distribution.