An assembly comprising an expandable corpectomy cage and an insertion instrument, wherein the expandable cage comprises an instrument attachment features, including mating holes on the sides of the outer sleeve, and a ball-shaped pocket on the endplate of the inner sleeve, and the insertion instrument features a tuning-fork shaped holder, which attaches to the mating holes on the implant's outer sleeve using small bosses which mate with the holes under the spring tension of the fork, and a lever with a spherical end that mates with the ball-shaped pocket in the inner sleeve endplate.