“…15–18 There is a correlation between implant stiffness, instantaneous axis of rotation, and interbody loading. 15,16 If too rigid, the plate will stress-shield, reverse load the graft, and have a high likelihood of causing subsidence and graft failure or screw loosening. 19–22 If too flexible, excess motion between the graft and endplates will favor pseudarthrosis over fusion.…”