Instrumentation tools like screws and rods aid posterior cervical fusion success by providing rigid fixation and stabilization of the spinal segments. Lateral mass and pedicle screws immobilize the vertebrae, while rods connect the screws to maintain alignment as bone grafts fuse. Pre-contoured rods restore cervical curvature. Plates and cages offer additional stability. This rigid instrumentation minimizes motion, allowing the bone graft to fuse properly and reducing the risk of non-union, i.e., failure of the bone to heal solidly.