An inserter instrument for inserting an intervertebral fusion cage having curved sidewalls, comprising: a) a threaded securement rod that mates with the cage via screw threads; b) a cannulated cage holder to receive the rod and hold the cage in position as the sheath is retracted; and c) a bulleted cannulated sheath, wherein the sheath is curved and comprises a superelastic shape memory material having a curved configuration and a straight configuration.