Biomechanical Comparison of Unilateral and Bilateral Pedicle Screw Fixation after Multilevel Lumbar Lateral Interbody Fusion.

Considerable decreases in ROM were observed after multilevel (4-level) LLIF utilizing 26 mm cages supplemented with both unilateral and bilateral pedicle screws and rods. The addition of bilateral fixation provides a 10-25% additional decrease in ROM. These results can inform surgeons of the incremental biomechanical benefit when considering unilateral or bilateral posterior fixation after multilevel LLIF.