Spinal cage devices, systems, and methods of assembly and implanting the devices and systems are disclosed. The cage system includes a cage and at least one locking screw assembly configured to couple to the cage. The spinal cage system includes a cage with a body portion, an external plate, and a rod. The body portion includes at least one opening positioned between the first and second ends, a center opening in the first end, and at least one hole adjacent the center opening. The external plate includes an opening and at least two holes on opposite sides of the opening. The rod extends through the center opening in the cage, the first end configured to couple to the external plate, and the second end positioned in the at least one opening. Methods for assembling a spinal cage system and for implanting a cage system are also disclosed.

In one embodiment, an intervertebral implant includes a body and a locking element. The body includes a leading surface and a trailing surface opposite the leading surface. The body also includes first and second bone fastener passageways through the implant body and a cavity in between the first and second passageways. The cavity includes a trailing wall that separates the cavity from the trailing surface. The locking element is disposed in the cavity such that part of the locking element is visible through an access opening in the trailing wall so that the locking element may be rotated from outside of the implant. In a first rotational position, a first part of the locking element is located within one of the first and second passageways and in a second rotational position, the first part of the locking element is inside the body covered by the trailing wall.