Comparison of disc annulus stress at the adjacent level L3-L4 in flexion. The maximum stress occurred at anterior edge of the annulus fibrosus. FUS showed the greatest stress. AWEFUS showed the lowest stress because levels L3-L4 were shielded by the Awesome Dynamic Rod System. AWE showed lower annulus stress than did FUS owing to its preservation of motion, which alleviated the effect of the adjacent level.