An expandable cage system for use in spinal surgery includes a top portion having an outwardly extending top arm, and a bottom portion having an outwardly extending bottom arm. The bottom arm is configured to engage with the top arm such that upon engagement, the top portion and the bottom portion are substantially restricted from movement relative to each other in an anterior-posterior direction, and in a medial-lateral direction. The expandable cage system further includes a removable shim configured to be positioned between the top portion and the bottom portion to hold the expandable cage in an expanded position within a spinal cavity.