Abstract: Objective To explore the mechanical stability of translaminar facet screw( TFS) and pedicle screw( PS)in anterior lumbar interbody fusion( ALIF)and whether the two posterior instrumentations have the same influence on the adjacent segments in two level anterior lumbar interbody fusion. Methods Normal adult human fresh corpses were used as spine samples,16 lumbar spines were randomed into no surgery group( intact),ALIF group,ALIF + TFS group and ALIF + PS group. Under 400N compressive preload and 75N/ m speed,comparisons were performed in the stiffness,motion range of adjacent segments and intervertebral disc pressure among different groups. Results Compared with intact group,ALIF group showed increase in flexion,lateral bending axial rotation,but decrease in extension. Comparisons among ALIF group,ALIF + TFS group and ALIF + PS group,ALIF group also showed increase in flexion,lateral bending,axial rotation,and the fixation stability by TFS and PS were similar, the difference was no significant,but TFS exerted less compressive stress on the adjacent segments of intervertebral discs. Conclusion TFS can provide the stability equivalent to PS in two-segment ALIF, TFS is the ideal choice in the operation.

Key words: lumbar vertebrae, anterior lumbar interbody fusion, translaminar facet screw, pedicle screw