Immediate stress and strain analysis of posterior pedicle screw fixation combined with different fusion cages in C5/6discectomy of simulated pig cervical vertebrae / 中国组织工程研究

ABSTRACT

BACKGROUND: Posterior decompression and pedicle screw fixation combined with interbody fusion is a method for the treatment of cervical vertebral degenerative lesions. There are few reports on the measurement of strain electricity in simulating C5/6 intervertebral disc fusion after pedicle screw removal. OBJECTIVE: To analyze stress and strain immediately after C5/6 discectomy, pedicle screw fixation combined with interbody fusion. METHODS: Eighteen fresh pig cervical specimens were randomly divided into three groups: Bone cage fusion group, PEEK fusion group, and titanium mesh fusion group (n=6). Each group simulated C5/6 discectomy and pedicle screw fixation, and then different fusion cages were used for interbody fusion. Before and after fusion, the resistance strain gauges were attached under the vertebral body at the position of pedicle screw fixation, at the edge of vertebral body at the fusion position of fusion cage, at the edge of adjacent vertebral body. The strain values of each sample were measured under the compression state by static resistance strain gauge. The stress values at each measurement point before and after fusion in posterior fixation with pedicle screws for cervical vertebrae in each group were calculated by material mechanics formula. RESULTS AND CONCLUSION: (1) Under the same load, the strain and stress of each measurement point in the titanium mesh fusion group were smaller than those in the bone cage fusion group and the PEEK fusion group, and the difference was significant (P < 0.05). (2) Under the same load, the strain and stress of each test point in the bone cage fusion group were larger than those in the PEEK fusion group, and the difference was significant (P < 0.05). (3) These results confirm that simulated C5 discectomy in vitro, posterior pedicle screw fixation and implantation of different fusion cages have different changes of stress and strain. The selection of appropriate interbody fusion cage can reduce the effect of stress concentration on adjacent segments.