Two screw and four screw implants provide comparable stability, fusion rates and clinical outcomes. However, the two screw implant was inferior to the four screw implant in subsidence prevention. Therefore, the two-screw implant is non-inferior to the four-screw implant in most patients. It can be used as the priority choice in the fusion segment by its easy manageability. However, the patients with a high risk of subsidence such as multilevel surgery, the elderly, lower BMD, bad cervical alignment should receive a four screw implant rather than a two screw implant.