Do translaminar facet screws have the same stability as pedicle screws in two-level anterior lumbar interbody fusion? A biomechanical study.

AIM: To determine whether translaminar facet screws can provide stability equivalent to pedicle screws in two-level anterior lumbar interbody fusion.

MATERIAL AND METHODS: We performed a biomechanical study using 12 fresh human lumbar spines and tested intact spine, stand-alone two-level ALIF and anterior fusion augmented with pedicle screws or translaminar facet screws under 400N compressive preloads and 7.5Nm moments in flexion, extension, axial rotation and lateral bending, and measured the range of motion and the stiffness of operative level.

RESULTS: We found two-level ALIF had significantly reduced range of motion, greater stiffness at operative segments in flexion, axial rotation and lateral bending (p < 0.05), but decreased stiffness and increased range of motion in extension (p < 0.05), when compared to intact spine. The two augmented ALIF constructs have significantly reduced range of motion (p < 0.05) and increased stiffness at operative level (p < 0.05), when compared to intact spine or stand-alone two-level ALIF. There is no significant difference of range of motion and stiffness at operative level between the two augmented constructs in all loading directions (p > 0.05).

CONCLUSION: Translaminar facet screws can provide stability equivalent to pedicle screws, and we recommend translaminar facet screws as perfect alternatives to pedicle screws in two-level ALIF.