Effect of expandable pedicle screw fixation on the fixation strength of osteoporotic thoracic and lumbar vertebrae / 中国组织工程研究

ABSTRACT

BACKGROUND: Studies have shown that osteoporosis often leads to a failure in pedicle screw fixation. Considering that the use of ordinary pedicle screw fixation cannot achieve a strong and stable fixation of the osteoporotic vertebra,special measures to strengthen the internal fixation is indispensable.OBJECTIVE: To evaluate the effect of bone cement augmentation combined with expandable pedicle screw fixation on the fixation strength of osteoporotic thoracolumbar vertebrae.METHODS: Twenty osteoporotic thoracolumbar vertebral specimens were randomly divided into four groups conventional pedicle screw group implanted with normal pedicle screw, and the other three groups implanted with expandable pedicle screw. Bone cement augmentation with polymethylmethacrylate (PMMA) and calcium sulfate was done in the PMMA group and calcium sulfate group, respectively, followed by expandable pedicle screw implantation. No bone cement was used in the expandable pedicle screw group. The maximum axial pull-out strength and yield energy absorption value of the unilateral pedicle were detected, and the maximum removal torque of the contralateral pedicle was determined. Bone cement leakage after augmentation was observed.RESULTS AND CONCLUSION: Compared with the conventional pedicle screw group, the other three groups showed a significant increase in the maximum pull-out strength, maximum removal torque and yield energy absorption values (P 0.05). No leakage of bone cement was found in all the groups. To conclude, the combined use of expandable pedicle screw and can significantly enhance the stability of the osteoporotic thoracolumbar vertebrae, and the PMMA and calcium sulfate cements have similar effects.