Patent ID: 7828848

Claim:
An implant for inserting between two vertebrae and for providing proper vertebral spacing, the implant comprising: a base having a proximal end and a distal end; at least three branches attached to the distal end of the base and extending in a distal direction away from the base, the base and the branches forming a hollow cage defining an internal volume, each branch having an inward side and an outward side; a spacer sized to fit within the cage and adapted to move along the inward side of each branch upon the urging of an implant-installing instrument, the spacer having a thickness substantially less than the length of the cage, said spacer and cage being sized so that each branch will move to an extended position when the spacer is urged in the distal direction from the base toward a distal end of the implant along the inward side of each branch by the implant-installing instrument; an aperture formed in the base extending from the internal volume of the cage and through the base to an outward end of the base, the aperture adapted to allow the implant-installing instrument to be inserted through the base to engage the spacer within the cage; and a plug that is removably attached to the proximal end of the base to prevent graft material inside the cage from escaping via the proximal end, wherein a substantial portion of the internal volume is empty after insertion of the spacer, and said portion is substantially larger than the portion of the internal volume occupied by structure of the implant, thereby permitting insertion of the graft material in an amount sufficient to achieve vertebral fusion.